16-BIT LANGUAGE TOOLS LIBRARIES (c) 2008 Microchip Technology Inc. DS51456E Note the following details of the code protection feature on Microchip devices: * Microchip products meet the specification contained in their particular Microchip Data Sheet. * Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. * There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip's Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. * Microchip is willing to work with the customer who is concerned about the integrity of their code. * Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as "unbreakable." Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip's code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, Accuron, dsPIC, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, PRO MATE, rfPIC and SmartShunt are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, PICkit, PICDEM, PICDEM.net, PICtail, PIC32 logo, PowerCal, PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, Select Mode, Total Endurance, UNI/O, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. (c) 2008, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company's quality system processes and procedures are for its PIC(R) MCUs and dsPIC(R) DSCs, KEELOQ(R) code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip's quality system for the design and manufacture of development systems is ISO 9001:2000 certified. DS51456E-page ii (c) 2008 Microchip Technology Inc. 16-BIT LANGUAGE TOOLS LIBRARIES Table of Contents Preface ........................................................................................................................... 1 Chapter 1. Library Overview 1.1 Introduction ..................................................................................................... 7 1.2 OMF-Specific Libraries/Start-up Modules ...................................................... 8 1.3 Start-up Code ................................................................................................. 8 1.4 DSP Library .................................................................................................... 8 1.5 16-Bit Peripheral Libraries .............................................................................. 8 1.6 Standard C Libraries with Math and Support Functions ................................. 9 1.7 Fixed Point Math Functions ............................................................................ 9 1.8 Compiler Built-in Functions ............................................................................ 9 Chapter 2. Standard C Libraries 2.1 Introduction ................................................................................................... 11 2.2 Using the Standard C Libraries .................................................................... 12 2.3 <assert.h> diagnostics ................................................................................. 13 2.4 <ctype.h> character handling ....................................................................... 14 2.5 <errno.h> errors ........................................................................................... 23 2.6 <float.h> floating-point characteristics .......................................................... 24 2.7 <limits.h> implementation-defined limits ...................................................... 29 2.8 <locale.h> localization .................................................................................. 31 2.9 <setjmp.h> non-local jumps ......................................................................... 32 2.10 <signal.h> signal handling .......................................................................... 33 2.11 <stdarg.h> variable argument lists ............................................................. 39 2.12 <stddef.h> common definitions .................................................................. 41 2.13 <stdio.h> input and output .......................................................................... 43 2.14 <stdlib.h> utility functions ........................................................................... 90 2.15 <string.h> string functions ........................................................................ 114 2.16 <time.h> date and time functions ............................................................. 137 Chapter 3. Standard C Libraries - Math Functions 3.1 Introduction ................................................................................................. 145 3.2 Using the Standard C Libraries .................................................................. 145 3.3 <math.h> mathematical functions .............................................................. 147 (c) 2008 Microchip Technology Inc. DS51456E-page iii 16-Bit Language Tools Libraries Chapter 4. Standard C Libraries - Support Functions 4.1 Introduction ................................................................................................. 189 4.2 Using the Support Functions ...................................................................... 190 4.3 Standard C Library Helper Functions ......................................................... 191 4.4 Standard C Library Functions That Require Modification ........................... 196 4.5 Functions/Constants to Support A Simulated UART .................................. 197 4.6 Functions for Erasing and Writing EEDATA Memory ................................. 199 4.7 Functions for Erasing and Writing Flash Memory ...................................... 201 4.8 Functions for Specialized Copying and Initialization .................................. 203 Chapter 5. Fixed Point Math Functions 5.1 Introduction ................................................................................................. 207 5.2 Using the Fixed Point Libraries .................................................................. 207 5.3 <libq.h> mathematical functions ................................................................. 209 Appendix A. ASCII Character Set .............................................................................227 Index ...........................................................................................................................229 Worldwide Sales and Service ...................................................................................242 DS51456E-page iv (c) 2008 Microchip Technology Inc. 16-BIT LANGUAGE TOOLS LIBRARIES Preface NOTICE TO CUSTOMERS All documentation becomes dated, and this manual is no exception. Microchip tools and documentation are constantly evolving to meet customer needs, so some actual dialogs and/or tool descriptions may differ from those in this document. Please refer to our web site (www.microchip.com) to obtain the latest documentation available. Documents are identified with a "DS" number. This number is located on the bottom of each page, in front of the page number. The numbering convention for the DS number is "DSXXXXXA", where "XXXXX" is the document number and "A" is the revision level of the document. For the most up-to-date information on development tools, see the MPLAB(R) IDE on-line help. Select the Help menu, and then Topics to open a list of available on-line help files. INTRODUCTION This chapter contains general information that will be useful to know before using 16-bit libraries. Items discussed include: * * * * * * Document Layout Conventions Used in this Guide Recommended Reading The Microchip Web Site Development Systems Customer Change Notification Service Customer Support DOCUMENT LAYOUT This document describes how to use GNU language tools to write code for 16-bit applications. The document layout is as follows: * Chapter 1: Library Overview - gives an overview of libraries. Some are described further in this document, while others are described in other documents or on-line Help files. * Chapter 2: Standard C Libraries - lists the library functions and macros for standard C operation. * Chapter 3: Standard C Libraries - Math Functions - lists the math functions for standard C operation. * Chapter 4: Standard C Libraries - Support Functions - lists standard C library helper functions. * Appendix A: ASCII Character Set (c) 2008 Microchip Technology Inc. DS51456E-page 1 16-Bit Language Tools Libraries CONVENTIONS USED IN THIS GUIDE The following conventions may appear in this documentation: DOCUMENTATION CONVENTIONS Description Represents Examples Arial font: MPLAB(R)(R) IDE User's Guide Italic Referenced books Emphasized text ...is the only compiler... Initial caps A window the Output window A dialog the Settings dialog A menu selection select Enable Programmer Quotes A field name in a window or dialog "Save project before build" Underlined, italic with right angle bracket A menu path File>Save Bold A dialog button Click OK A tab Click the Power tab A key on the keyboard Press <Enter>, <F1> Sample source code #define START Filenames autoexec.bat File paths c:\mcc18\h Keywords _asm, _endasm, static Command-line options -Opa+, -Opa- Bit values 0, 1 Constants 0xFF, 'A' Italic A variable argument file.o, where file can be any valid filename Square brackets [ ] Optional arguments mpasmwin [options] file [options] Curly brackets and pipe character: { | } Choice of mutually exclusive arguments; an OR selection errorlevel {0|1} Ellipses... Replaces repeated text var_name [, var_name...] Represents code supplied by user void main (void) { ... } Text in angle brackets < > Courier New font: Plain DS51456E-page 2 (c) 2008 Microchip Technology Inc. Preface RECOMMENDED READING This documentation describes how to use 16-bit libraries. Other useful documents are listed below. The following Microchip documents are available and recommended as supplemental reference resources. Readme Files For the latest information on Microchip tools, read the associated Readme files (HTML files) included with the software. 16-Bit Language Tools Getting Started (DS70094) A guide to installing and working with the Microchip language tools for 16-bit devices. Examples using the 16-bit simulator SIM30 (a component of MPLAB SIM) are provided. MPLAB(R) Assembler, Linker and Utilities for PIC24 MCUs and dsPIC(R) DSCs User's Guide (DS51317) A guide to using the 16-bit assembler, object linker, and various utilities, including the 16-bit archiver/librarian. MPLAB C Compiler for PIC24 MCUs and dsPIC(R) DSCs User's Guide (DS51284) A guide to using the 16-bit C compiler. The 16-bit linker is used with this tool. Device-Specific Documentation The Microchip website contains many documents that describe 16-bit device functions and features. Among these are: * Individual and family data sheets * Family reference manuals * Programmer's reference manuals C Standards Information American National Standard for Information Systems - Programming Language - C. American National Standards Institute (ANSI), 11 West 42nd. Street, New York, New York, 10036. This standard specifies the form and establishes the interpretation of programs expressed in the programming language C. Its purpose is to promote portability, reliability, maintainability and efficient execution of C language programs on a variety of computing systems. C Reference Manuals Harbison, Samuel P. and Steele, Guy L., C A Reference Manual, Fourth Edition, Prentice-Hall, Englewood Cliffs, N.J. 07632. Kernighan, Brian W. and Ritchie, Dennis M., The C Programming Language, Second Edition. Prentice Hall, Englewood Cliffs, N.J. 07632. Kochan, Steven G., Programming In ANSI C, Revised Edition. Hayden Books, Indianapolis, Indiana 46268. Plauger, P.J., The Standard C Library, Prentice-Hall, Englewood Cliffs, N.J. 07632. Van Sickle, Ted., Programming Microcontrollers in C, First Edition. LLH Technology Publishing, Eagle Rock, Virginia 24085. (c) 2008 Microchip Technology Inc. DS51456E-page 3 16-Bit Language Tools Libraries THE MICROCHIP WEB SITE Microchip provides online support via our web site at www.microchip.com. This web site is used as a means to make files and information easily available to customers. Accessible by using your favorite Internet browser, the web site contains the following information: * Product Support - Data sheets and errata, application notes and sample programs, design resources, user's guides and hardware support documents, latest software releases and archived software * General Technical Support - Frequently Asked Questions (FAQs), technical support requests, online discussion groups, Microchip consultant program member listing * Business of Microchip - Product selector and ordering guides, latest Microchip press releases, listing of seminars and events, listings of Microchip sales offices, distributors and factory representatives DEVELOPMENT SYSTEMS CUSTOMER CHANGE NOTIFICATION SERVICE Microchip's customer notification service helps keep customers current on Microchip products. Subscribers will receive e-mail notification whenever there are changes, updates, revisions or errata related to a specified product family or development tool of interest. To register, access the Microchip web site at www.microchip.com, click on Customer Change Notification and follow the registration instructions. The Development Systems product group categories are: * Compilers - The latest information on Microchip C compilers, assemblers, linkers and other language tools. These include all MPLAB(R) C compilers; all MPLAB assemblers (including MPASMTM assembler); all MPLAB linkers (including MPLINKTM object linker); and all MPLAB librarians (including MPLIBTM object librarian). * Emulators - The latest information on Microchip in-circuit emulators.These include the MPLAB REAL ICETM, MPLAB ICE 2000 and MPLAB ICE 4000 in-circuit emulators * In-Circuit Debuggers - The latest information on Microchip in-circuit debuggers. These include the MPLAB ICD 2 in-circuit debugger and PICkitTM 2 debug express. * MPLAB(R) IDE - The latest information on Microchip MPLAB IDE, the Windows(R) Integrated Development Environment for development systems tools. This list is focused on the MPLAB IDE, MPLAB IDE Project Manager, MPLAB Editor and MPLAB SIM simulator, as well as general editing and debugging features. * Programmers - The latest information on Microchip programmers. These include the MPLAB PM3 and PRO MATE(R) II device programmers and the PICSTART(R) Plus and PICkit 1 and 2 development programmers. DS51456E-page 4 (c) 2008 Microchip Technology Inc. Preface CUSTOMER SUPPORT Users of Microchip products can receive assistance through several channels: * * * * Distributor or Representative Local Sales Office Field Application Engineer (FAE) Technical Support Customers should contact their distributor, representative or field application engineer (FAE) for support. Local sales offices are also available to help customers. A listing of sales offices and locations is included in the back of this document. Technical support is available through the web site at: http://support.microchip.com (c) 2008 Microchip Technology Inc. DS51456E-page 5 16-Bit Language Tools Libraries NOTES: DS51456E-page 6 (c) 2008 Microchip Technology Inc. 16-BIT LANGUAGE TOOLS LIBRARIES Chapter 1. Library Overview 1.1 INTRODUCTION A library is a collection of functions grouped for reference and ease of linking. See the "MPLAB(R) Assembler, Linker and Utilities for PIC24 MCUs and dsPIC(R) DSCs User's Guide" (DS51317) for more information about making and using libraries. 1.1.1 Assembly Code Applications Free versions of the 16-bit language tool libraries are available from the Microchip web site. DSP and 16-bit peripheral libraries are provided with object files and source code. A math library containing functions from the standard C header file <math.h> is provided as an object file only. The complete standard C library is provided with the MPLAB C Compiler for PIC24 MCUs and dsPIC(R) DSCs (formerly MPLAB C30). 1.1.2 C Code Applications The 16-bit language tool libraries are included in the lib subdirectory of the MPLAB C Compiler for PIC24 MCUs and dsPIC(R) DSCs install directory, which is by default: C:\Program Files\Microchip\MPLAB C30\lib These libraries can be linked directly into an application with 16-bit linker. 1.1.3 Chapter Organization This chapter is organized as follows: * * * * * * * OMF-Specific Libraries/Start-up Modules Start-up Code DSP Library 16-Bit Peripheral Libraries Standard C Libraries with Math and Support Functions Fixed Point Math Functions Compiler Built-in Functions (c) 2008 Microchip Technology Inc. DS51456E-page 7 16-Bit Language Tools Libraries 1.2 OMF-SPECIFIC LIBRARIES/START-UP MODULES Library files and start-up modules are specific to OMF (Object Module Format). An OMF can be one of the following: * COFF - This is the default. * ELF - The debugging format used for ELF object files is DWARF 2.0. There are two ways to select the OMF: 1. Set an environment variable called PIC30_OMF for all tools. 2. Select the OMF on the command line when invoking the tool, i.e., -omf=omf or -momf=omf . 16-bit tools will first look for generic library files when building your application (no OMF specification). If these cannot be found, the tools will look at your OMF specifications and determine which library file to use. As an example, if libdsp.a is not found and no environment variable or command-line option is set, the file libdsp-coff.a will be used by default. 1.3 START-UP CODE In order to initialize variables in data memory, the linker creates a data initialization template. This template must be processed at start-up, before the application proper takes control. For C programs, this function is performed by the start-up modules in libpic30-coff.a (either crt0.o or crt1.o) or libpic30-elf.a (either crt0.eo or crt1.eo). Assembly language programs can utilize these modules directly by linking with the desired start-up module file. The source code for the start-up modules is provided in corresponding .s files. The primary start-up module (crt0) initializes all variables (variables without initializers are set to zero as required by the ANSI standard) except for variables in the persistent data section. The alternate start-up module (crt1) performs no data initialization. For more on start-up code, see the "MPLAB(R) Assembler, Linker and Utilities for PIC24 MCUs and dsPIC(R) DSCs User's Guide" (DS51317) and, for C applications, the "MPLAB(R) C Compiler for PIC24 MCUs and dsPIC(R) DSCs User's Guide" (DS51284). 1.4 DSP LIBRARY The DSP library (libdsp-omf.a) provides a set of digital signal processing operations to a program targeted for execution on a dsPIC30F digital signal controller (DSC). In total, 49 functions are supported by the DSP Library. Documentation for these libraries is provided in HTML Help files. Examples of use may also provided. By default, the documentation is found in: C:\Program Files\Microchip\MPLAB C30\docs\dsp_lib 1.5 16-BIT PERIPHERAL LIBRARIES The 16-bit software and hardware peripheral libraries provide functions and macros for setting up and controlling 16-bit peripherals. These libraries are processor-specific and of the form libpDevice-omf.a, where Device is the 16-bit device number (e.g., libp30F6014-coff.a for the dsPIC30F6014 device) and omf is either coff or elf. Documentation for these libraries is provided in HTML Help files. Examples of use are also provided in each file. By default, the documentation is found in: C:\Program Files\Microchip\MPLAB C30\docs\periph_lib DS51456E-page 8 (c) 2008 Microchip Technology Inc. Library Overview 1.6 STANDARD C LIBRARIES WITH MATH AND SUPPORT FUNCTIONS A complete set of ANSI-89 conforming libraries are provided. The standard C library files are libc-omf.a (written by Dinkumware, an industry leader) and libm-omf.a (math functions, written by Microchip). Additionally, some 16-bit standard C library helper functions, and standard functions that must be modified for use with 16-bit devices, are in libpic30-omf.a. A typical C application will require these libraries. Documentation for these library functions is contained in this manual. 1.7 FIXED POINT MATH FUNCTIONS Fixed point math functions may be found in the library file libq-omf.a. Documentation for these library functions is contained in this manual. 1.8 COMPILER BUILT-IN FUNCTIONS The MPLAB C Compiler for PIC24 MCUs and dsPIC(R) DSCs contains built-in functions that, to the developer, work like library functions. These functions are listed in the "MPLAB(R) C Compiler for PIC24 MCUs and dsPIC(R) DSCs Users' Guide" (DS51284). (c) 2008 Microchip Technology Inc. DS51456E-page 9 16-Bit Language Tools Libraries NOTES: DS51456E-page 10 (c) 2008 Microchip Technology Inc. 16-BIT LANGUAGE TOOLS LIBRARIES Chapter 2. Standard C Libraries 2.1 INTRODUCTION Standard ANSI C library functions are contained in the file libc-omf.a, where omf will be coff or elf depending upon the selected object module format. 2.1.1 Assembly Code Applications A free version of the math functions library and header file is available from the Microchip web site. No source code is available with this free version. 2.1.2 C Code Applications The MPLAB C Compiler for PIC24 MCUs and dsPIC(R) DSCs (formerly MPLAB C30) install directory (c:\Program Files\Microchip\MPLAB C30) contains the following subdirectories with library-related files: * lib - standard C library files * src\libm - source code for math library functions, batch file to rebuild the library * support\h - header files for libraries In addition, there is a file, ResourceGraphs.pdf, which contains diagrams of resources used by each function, located in lib. 2.1.3 Chapter Organization This chapter is organized as follows: * * * * * * * * * * * * * * * Using the Standard C Libraries <assert.h> diagnostics <ctype.h> character handling <errno.h> errors <float.h> floating-point characteristics <limits.h> implementation-defined limits <locale.h> localization <setjmp.h> non-local jumps <signal.h> signal handling <stdarg.h> variable argument lists <stddef.h> common definitions <stdio.h> input and output <stdlib.h> utility functions <string.h> string functions <time.h> date and time functions (c) 2008 Microchip Technology Inc. DS51456E-page 11 16-Bit Language Tools Libraries 2.2 USING THE STANDARD C LIBRARIES Building an application which utilizes the standard C libraries requires two types of files: header files and library files. 2.2.1 Header Files All standard C library entities are declared or defined in one or more standard headers (See list in Section 2.1.3 "Chapter Organization".) To make use of a library entity in a program, write an include directive that names the relevant standard header. The contents of a standard header is included by naming it in an include directive, as in: #include <stdio.h> /* include I/O facilities */ The standard headers can be included in any order. Do not include a standard header within a declaration. Do not define macros that have the same names as keywords before including a standard header. A standard header never includes another standard header. 2.2.2 Library Files The archived library files contain all the individual object files for each library function. When linking an application, the library file must be provided as an input to the linker (using the --library or -l linker option) such that the functions used by the application may be linked into the application. A typical C application will require three library files: libc-omf.a, libm-omf.a, and libpic30-omf.a. (See Section 1.2 "OMF-Specific Libraries/Start-up Modules" for more on OMF-specific libraries.) These libraries will be included automatically if linking is performed using the compiler. Note: DS51456E-page 12 Some standard library functions require a heap. These include the standard I/O functions that open files and the memory allocation functions. See the "MPLAB(R) Assembler, Linker and Utilities for PIC24 MCUs and dsPIC(R) DSCs User's Guide" (DS51317) and "MPLAB(R) C Compiler for PIC24 MCUs and dsPIC(R) DSCs User's Guide" (DS51284) for more information on the heap. (c) 2008 Microchip Technology Inc. Standard C Libraries 2.3 <ASSERT.H> DIAGNOSTICS The header file assert.h consists of a single macro that is useful for debugging logic errors in programs. By using the assert statement in critical locations where certain conditions should be true, the logic of the program may be tested. Assertion testing may be turned off without removing the code by defining NDEBUG before including <assert.h>. If the macro NDEBUG is defined, assert() is ignored and no code is generated. assert Description: If the expression is false, an assertion message is printed to stderr and the program is aborted. Include: <assert.h> Prototype: void assert(int expression); Argument: expression The expression to test. Remarks: The expression evaluates to zero or non-zero. If zero, the assertion fails, and a message is printed to stderr. The message includes the source file name (__FILE__), the source line number (__LINE__), the expression being evaluated and the message. The macro then calls the function abort(). If the macro _VERBOSE_DEBUGGING is defined, a message will be printed to stderr each time assert() is called. Example: #include <assert.h> /* for assert */ int main(void) { int a; a = 2 * 2; assert(a == 4); /* if true-nothing prints */ assert(a == 6); /* if false-print message */ /* and abort */ } Output: sampassert.c:9 a == 6 -- assertion failed ABRT with _VERBOSE_DEBUGGING defined: sampassert.c:8 a == 4 -- OK sampassert.c:9 a == 6 -- assertion failed ABRT (c) 2008 Microchip Technology Inc. DS51456E-page 13 16-Bit Language Tools Libraries 2.4 <CTYPE.H> CHARACTER HANDLING The header file ctype.h consists of functions that are useful for classifying and mapping characters. Characters are interpreted according to the Standard C locale. isalnum Description: Test for an alphanumeric character. Include: <ctype.h> Prototype: int isalnum(int c); Argument: c Return Value: Returns a non-zero integer value if the character is alphanumeric; otherwise, returns a zero. Remarks: Alphanumeric characters are included within the ranges A-Z, a-z or 0-9. Example: #include <ctype.h> /* for isalnum */ #include <stdio.h> /* for printf */ The character to test. int main(void) { int ch; ch = '3'; if (isalnum(ch)) printf("3 is an alphanumeric\n"); else printf("3 is NOT an alphanumeric\n"); ch = '#'; if (isalnum(ch)) printf("# is an alphanumeric\n"); else printf("# is NOT an alphanumeric\n"); } Output: 3 is an alphanumeric # is NOT an alphanumeric isalpha DS51456E-page 14 Description: Test for an alphabetic character. Include: <ctype.h> Prototype: int isalpha(int c); Argument: c Return Value: Returns a non-zero integer value if the character is alphabetic; otherwise, returns zero. Remarks: Alphabetic characters are included within the ranges A-Z or a-z. The character to test. (c) 2008 Microchip Technology Inc. Standard C Libraries isalpha (Continued) Example: #include <ctype.h> /* for isalpha */ #include <stdio.h> /* for printf */ int main(void) { int ch; ch = 'B'; if (isalpha(ch)) printf("B is alphabetic\n"); else printf("B is NOT alphabetic\n"); ch = '#'; if (isalpha(ch)) printf("# is alphabetic\n"); else printf("# is NOT alphabetic\n"); } Output: B is alphabetic # is NOT alphabetic iscntrl Description: Test for a control character. Include: <ctype.h> Prototype: int iscntrl(int c); Argument: c Return Value: Returns a non-zero integer value if the character is a control character; otherwise, returns zero. Remarks: A character is considered to be a control character if its ASCII value is in the range 0x00 to 0x1F inclusive, or 0x7F. Example: #include <ctype.h> /* for iscntrl */ #include <stdio.h> /* for printf */ character to test. int main(void) { char ch; ch = 'B'; if (iscntrl(ch)) printf("B is a control character\n"); else printf("B is NOT a control character\n"); ch = '\t'; if (iscntrl(ch)) printf("A tab is a control character\n"); else printf("A tab is NOT a control character\n"); } Output: B is NOT a control character A tab is a control character (c) 2008 Microchip Technology Inc. DS51456E-page 15 16-Bit Language Tools Libraries isdigit Description: Test for a decimal digit. Include: <ctype.h> Prototype: int isdigit(int c); Argument: c Return Value: Returns a non-zero integer value if the character is a digit; otherwise, returns zero. Remarks: A character is considered to be a digit character if it is in the range of `0'- `9'. Example: #include <ctype.h> /* for isdigit */ #include <stdio.h> /* for printf */ character to test. int main(void) { int ch; ch = '3'; if (isdigit(ch)) printf("3 is a digit\n"); else printf("3 is NOT a digit\n"); ch = '#'; if (isdigit(ch)) printf("# is a digit\n"); else printf("# is NOT a digit\n"); } Output: 3 is a digit # is NOT a digit isgraph Description: Test for a graphical character. Include: <ctype.h> Prototype: int isgraph (int c); Argument: c Return Value: Returns a non-zero integer value if the character is a graphical character; otherwise, returns zero. Remarks: A character is considered to be a graphical character if it is any printable character except a space. Example: #include <ctype.h> /* for isgraph */ #include <stdio.h> /* for printf */ character to test int main(void) { int ch; DS51456E-page 16 (c) 2008 Microchip Technology Inc. Standard C Libraries isgraph (Continued) ch = '3'; if (isgraph(ch)) printf("3 is a graphical character\n"); else printf("3 is NOT a graphical character\n"); ch = '#'; if (isgraph(ch)) printf("# is a graphical character\n"); else printf("# is NOT a graphical character\n"); ch = ' '; if (isgraph(ch)) printf("a space is a graphical character\n"); else printf("a space is NOT a graphical character\n"); } Output: 3 is a graphical character # is a graphical character a space is NOT a graphical character islower Description: Test for a lower case alphabetic character. Include: <ctype.h> Prototype: int islower (int c); Argument: c Return Value: Returns a non-zero integer value if the character is a lower case alphabetic character; otherwise, returns zero. Remarks: A character is considered to be a lower case alphabetic character if it is in the range of `a'-`z'. Example: #include <ctype.h> /* for islower */ #include <stdio.h> /* for printf */ character to test int main(void) { int ch; ch = 'B'; if (islower(ch)) printf("B is lower case\n"); else printf("B is NOT lower case\n"); ch = 'b'; if (islower(ch)) printf("b is lower case\n"); else printf("b is NOT lower case\n"); } (c) 2008 Microchip Technology Inc. DS51456E-page 17 16-Bit Language Tools Libraries islower (Continued) Output: B is NOT lower case b is lower case isprint Description: Test for a printable character (includes a space). Include: <ctype.h> Prototype: int isprint (int c); Argument: c Return Value: Returns a non-zero integer value if the character is printable; otherwise, returns zero. Remarks: A character is considered to be a printable character if it is in the range 0x20 to 0x7e inclusive. Example: #include <ctype.h> /* for isprint */ #include <stdio.h> /* for printf */ character to test int main(void) { int ch; ch = '&'; if (isprint(ch)) printf("& is a printable character\n"); else printf("& is NOT a printable character\n"); ch = '\t'; if (isprint(ch)) printf("a tab is a printable character\n"); else printf("a tab is NOT a printable character\n"); } Output: & is a printable character a tab is NOT a printable character ispunct DS51456E-page 18 Description: Test for a punctuation character. Include: <ctype.h> Prototype: int ispunct (int c); Argument: c Return Value: Returns a non-zero integer value if the character is a punctuation character; otherwise, returns zero. Remarks: A character is considered to be a punctuation character if it is a printable character which is neither a space nor an alphanumeric character. Punctuation characters consist of the following: !"#$%&'();<=>?@[\]*+,-./:^_{|}~ character to test (c) 2008 Microchip Technology Inc. Standard C Libraries ispunct (Continued) Example: #include <ctype.h> /* for ispunct */ #include <stdio.h> /* for printf */ int main(void) { int ch; ch = '&'; if (ispunct(ch)) printf("& is a punctuation character\n"); else printf("& is NOT a punctuation character\n"); ch = '\t'; if (ispunct(ch)) printf("a tab is a punctuation character\n"); else printf("a tab is NOT a punctuation character\n"); } Output: & is a punctuation character a tab is NOT a punctuation character isspace Description: Test for a white-space character. Include: <ctype.h> Prototype: int isspace (int c); Argument: c Return Value: Returns a non-zero integer value if the character is a white-space character; otherwise, returns zero. Remarks: A character is considered to be a white-space character if it is one of the following: space (' '), form feed ('\f'), newline ('\n'), carriage return ('\r'), horizontal tab ('\t'), or vertical tab ('\v'). Example: #include <ctype.h> /* for isspace */ #include <stdio.h> /* for printf */ character to test int main(void) { int ch; ch = '&'; if (isspace(ch)) printf("& is a white-space character\n"); else printf("& is NOT a white-space character\n"); ch = '\t'; if (isspace(ch)) printf("a tab is a white-space character\n"); else printf("a tab is NOT a white-space character\n"); } (c) 2008 Microchip Technology Inc. DS51456E-page 19 16-Bit Language Tools Libraries isspace (Continued) Output: & is NOT a white-space character a tab is a white-space character isupper Description: Test for an upper case letter. Include: <ctype.h> Prototype: int isupper (int c); Argument: c Return Value: Returns a non-zero integer value if the character is an upper case alphabetic character; otherwise, returns zero. Remarks: A character is considered to be an upper case alphabetic character if it is in the range of `A'-`Z'. Example: #include <ctype.h> /* for isupper */ #include <stdio.h> /* for printf */ character to test int main(void) { int ch; ch = 'B'; if (isupper(ch)) printf("B is upper case\n"); else printf("B is NOT upper case\n"); ch = 'b'; if (isupper(ch)) printf("b is upper case\n"); else printf("b is NOT upper case\n"); } Output: B is upper case b is NOT upper case isxdigit DS51456E-page 20 Description: Test for a hexadecimal digit. Include: <ctype.h> Prototype: int isxdigit (int c); Argument: c Return Value: Returns a non-zero integer value if the character is a hexadecimal digit; otherwise, returns zero. Remarks: A character is considered to be a hexadecimal digit character if it is in the range of `0'-`9', `A'-`F', or `a'-`f'. Note: The list does not include the leading 0x because 0x is the prefix for a hexadecimal number but is not an actual hexadecimal digit. character to test (c) 2008 Microchip Technology Inc. Standard C Libraries isxdigit (Continued) Example: #include <ctype.h> /* for isxdigit */ #include <stdio.h> /* for printf */ int main(void) { int ch; ch = 'B'; if (isxdigit(ch)) printf("B is a hexadecimal digit\n"); else printf("B is NOT a hexadecimal digit\n"); ch = 't'; if (isxdigit(ch)) printf("t is a hexadecimal digit\n"); else printf("t is NOT a hexadecimal digit\n"); } Output: B is a hexadecimal digit t is NOT a hexadecimal digit tolower Description: Convert a character to a lower case alphabetical character. Include: <ctype.h> Prototype: int tolower (int c); Argument: c Return Value: Returns the corresponding lower case alphabetical character if the argument was originally upper case; otherwise, returns the original character. Remarks: Only upper case alphabetical characters may be converted to lower case. Example: #include <ctype.h> /* for tolower */ #include <stdio.h> /* for printf */ The character to convert to lower case. int main(void) { int ch; ch = 'B'; printf("B changes to lower case %c\n", tolower(ch)); ch = 'b'; printf("b remains lower case %c\n", tolower(ch)); ch = '@'; printf("@ has no lower case, "); printf("so %c is returned\n", tolower(ch)); } (c) 2008 Microchip Technology Inc. DS51456E-page 21 16-Bit Language Tools Libraries tolower (Continued) Output: B changes to lower case b b remains lower case b @ has no lower case, so @ is returned toupper Description: Convert a character to an upper case alphabetical character. Include: <ctype.h> Prototype: int toupper (int c); Argument: c Return Value: Returns the corresponding upper case alphabetical character if the argument was originally lower case; otherwise, returns the original character. Remarks: Only lower case alphabetical characters may be converted to upper case. Example: #include <ctype.h> /* for toupper */ #include <stdio.h> /* for printf */ The character to convert to upper case. int main(void) { int ch; ch = 'b'; printf("b changes to upper case %c\n", toupper(ch)); ch = 'B'; printf("B remains upper case %c\n", toupper(ch)); ch = '@'; printf("@ has no upper case, "); printf("so %c is returned\n", toupper(ch)); } Output: b changes to upper case B B remains upper case B @ has no upper case, so @ is returned DS51456E-page 22 (c) 2008 Microchip Technology Inc. Standard C Libraries 2.5 <ERRNO.H> ERRORS The header file errno.h consists of macros that provide error codes that are reported by certain library functions (see individual functions). The variable errno may return any value greater than zero. To test if a library function encounters an error, the program should store the value zero in errno immediately before calling the library function. The value should be checked before another function call could change the value. At program start-up, errno is zero. Library functions will never set errno to zero. EDOM Description: Represents a domain error. Include: <errno.h> Remarks: EDOM represents a domain error, which occurs when an input argument is outside the domain in which the function is defined. ERANGE Description: Represents an overflow or underflow error. Include: <errno.h> Remarks: ERANGE represents an overflow or underflow error, which occurs when a result is too large or too small to be stored. errno Description: Contains the value of an error when an error occurs in a function. Include: <errno.h> Remarks: The variable errno is set to a non-zero integer value by a library function when an error occurs. At program start-up, errno is set to zero. Errno should be reset to zero prior to calling a function that sets it. (c) 2008 Microchip Technology Inc. DS51456E-page 23 16-Bit Language Tools Libraries 2.6 <FLOAT.H> FLOATING-POINT CHARACTERISTICS The header file float.h consists of macros that specify various properties of floating-point types. These properties include number of significant figures, size limits, and what rounding mode is used. DBL_DIG Description: Number of decimal digits of precision in a double precision floating-point value Include: <float.h> Value: 6 by default, 15 if the switch -fno-short-double is used Remarks: By default, a double type is the same size as a float type (32-bit representation). The -fno-short-double switch allows the IEEE 64-bit representation to be used for a double precision floating-point value. DBL_EPSILON Description: The difference between 1.0 and the next larger representable double precision floating-point value Include: <float.h> Value: 1.192093e-07 by default, 2.220446e-16 if the switch -fno-short-double is used Remarks: By default, a double type is the same size as a float type (32-bit representation). The -fno-short-double switch allows the IEEE 64-bit representation to be used for a double precision floating-point value. DBL_MANT_DIG Description: Number of base-FLT_RADIX digits in a double precision floating-point significand Include: <float.h> Value: 24 by default, 53 if the switch -fno-short-double is used Remarks: By default, a double type is the same size as a float type (32-bit representation). The -fno-short-double switch allows the IEEE 64-bit representation to be used for a double precision floating-point value. DBL_MAX DS51456E-page 24 Description: Maximum finite double precision floating-point value Include: <float.h> Value: 3.402823e+38 by default, 1.797693e+308 if the switch -fno-short-double is used Remarks: By default, a double type is the same size as a float type (32-bit representation). The -fno-short-double switch allows the IEEE 64-bit representation to be used for a double precision floating-point value. (c) 2008 Microchip Technology Inc. Standard C Libraries DBL_MAX_10_EXP Description: Maximum integer value for a double precision floating-point exponent in base 10 Include: <float.h> Value: 38 by default, 308 if the switch -fno-short-double is used Remarks: By default, a double type is the same size as a float type (32-bit representation). The -fno-short-double switch allows the IEEE 64-bit representation to be used for a double precision floating-point value. DBL_MAX_EXP Description: Maximum integer value for a double precision floating-point exponent in base FLT_RADIX Include: <float.h> Value: 128 by default, 1024 if the switch -fno-short-double is used Remarks: By default, a double type is the same size as a float type (32-bit representation). The -fno-short-double switch allows the IEEE 64-bit representation to be used for a double precision floating-point value. DBL_MIN Description: Minimum double precision floating-point value Include: <float.h> Value: 1.175494e-38 by default, 2.225074e-308 if the switch -fno-short-double is used Remarks: By default, a double type is the same size as a float type (32-bit representation). The -fno-short-double switch allows the IEEE 64-bit representation to be used for a double precision floating-point value. DBL_MIN_10_EXP Description: Minimum negative integer value for a double precision floating-point exponent in base 10 Include: <float.h> Value: -37 by default, -307 if the switch -fno-short-double is used Remarks: By default, a double type is the same size as a float type (32-bit representation). The -fno-short-double switch allows the IEEE 64-bit representation to be used for a double precision floating-point value. (c) 2008 Microchip Technology Inc. DS51456E-page 25 16-Bit Language Tools Libraries DBL_MIN_EXP Description: Minimum negative integer value for a double precision floating-point exponent in base FLT_RADIX Include: <float.h> Value: -125 by default, -1021 if the switch -fno-short-double is used Remarks: By default, a double type is the same size as a float type (32-bit representation). The -fno-short-double switch allows the IEEE 64-bit representation to be used for a double precision floating-point value. FLT_DIG Description: Number of decimal digits of precision in a single precision floating-point value Include: <float.h> Value: 6 FLT_EPSILON Description: The difference between 1.0 and the next larger representable single precision floating-point value Include: <float.h> Value: 1.192093e-07 FLT_MANT_DIG Description: Number of base-FLT_RADIX digits in a single precision floating-point significand Include: <float.h> Value: 24 FLT_MAX Description: Maximum finite single precision floating-point value Include: <float.h> Value: 3.402823e+38 FLT_MAX_10_EXP DS51456E-page 26 Description: Maximum integer value for a single precision floating-point exponent in base 10 Include: <float.h> Value: 38 (c) 2008 Microchip Technology Inc. Standard C Libraries FLT_MAX_EXP Description: Maximum integer value for a single precision floating-point exponent in base FLT_RADIX Include: <float.h> Value: 128 FLT_MIN Description: Minimum single precision floating-point value Include: <float.h> Value: 1.175494e-38 FLT_MIN_10_EXP Description: Minimum negative integer value for a single precision floating-point exponent in base 10 Include: <float.h> Value: -37 FLT_MIN_EXP Description: Minimum negative integer value for a single precision floating-point exponent in base FLT_RADIX Include: <float.h> Value: -125 FLT_RADIX Description: Radix of exponent representation Include: <float.h> Value: 2 Remarks: The base representation of the exponent is base-2 or binary. FLT_ROUNDS Description: Represents the rounding mode for floating-point operations Include: <float.h> Value: 1 Remarks: Rounds to the nearest representable value LDBL_DIG Description: Number of decimal digits of precision in a long double precision floating-point value Include: <float.h> Value: 15 (c) 2008 Microchip Technology Inc. DS51456E-page 27 16-Bit Language Tools Libraries LDBL_EPSILON Description: The difference between 1.0 and the next larger representable long double precision floating-point value Include: <float.h> Value: 2.220446e-16 LDBL_MANT_DIG Description: Number of base-FLT_RADIX digits in a long double precision floating-point significand Include: <float.h> Value: 53 LDBL_MAX Description: Maximum finite long double precision floating-point value Include: <float.h> Value: 1.797693e+308 LDBL_MAX_10_EXP Description: Maximum integer value for a long double precision floating-point exponent in base 10 Include: <float.h> Value: 308 LDBL_MAX_EXP Description: Maximum integer value for a long double precision floating-point exponent in base FLT_RADIX Include: <float.h> Value: 1024 LDBL_MIN Description: Minimum long double precision floating-point value Include: <float.h> Value: 2.225074e-308 LDBL_MIN_10_EXP DS51456E-page 28 Description: Minimum negative integer value for a long double precision floating-point exponent in base 10 Include: <float.h> Value: -307 (c) 2008 Microchip Technology Inc. Standard C Libraries LDBL_MIN_EXP 2.7 Description: Minimum negative integer value for a long double precision floating-point exponent in base FLT_RADIX Include: <float.h> Value: -1021 <LIMITS.H> IMPLEMENTATION-DEFINED LIMITS The header file limits.h consists of macros that define the minimum and maximum values of integer types. Each of these macros can be used in #if preprocessing directives. CHAR_BIT Description: Number of bits to represent type char Include: <limits.h> Value: 8 CHAR_MAX Description: Maximum value of a char Include: <limits.h> Value: 127 CHAR_MIN Description: Minimum value of a char Include: <limits.h> Value: -128 INT_MAX Description: Maximum value of an int Include: <limits.h> Value: 32767 INT_MIN Description: Minimum value of an int Include: <limits.h> Value: -32768 LLONG_MAX Description: Maximum value of a long long int Include: <limits.h> Value: 9223372036854775807 (c) 2008 Microchip Technology Inc. DS51456E-page 29 16-Bit Language Tools Libraries LLONG_MIN Description: Minimum value of a long long int Include: <limits.h> Value: -9223372036854775808 LONG_MAX Description: Maximum value of a long int Include: <limits.h> Value: 2147483647 LONG_MIN Description: Minimum value of a long int Include: <limits.h> Value: -2147483648 MB_LEN_MAX Description: Maximum number of bytes in a multibyte character Include: <limits.h> Value: 1 SCHAR_MAX Description: Maximum value of a signed char Include: <limits.h> Value: 127 SCHAR_MIN Description: Minimum value of a signed char Include: <limits.h> Value: -128 SHRT_MAX Description: Maximum value of a short int Include: <limits.h> Value: 32767 SHRT_MIN DS51456E-page 30 Description: Minimum value of a short int Include: <limits.h> Value: -32768 (c) 2008 Microchip Technology Inc. Standard C Libraries UCHAR_MAX Description: Maximum value of an unsigned char Include: <limits.h> Value: 255 UINT_MAX Description: Maximum value of an unsigned int Include: <limits.h> Value: 65535 ULLONG_MAX Description: Maximum value of a long long unsigned int Include: <limits.h> Value: 18446744073709551615 ULONG_MAX Description: Maximum value of a long unsigned int Include: <limits.h> Value: 4294967295 USHRT_MAX 2.8 Description: Maximum value of an unsigned short int Include: <limits.h> Value: 65535 <LOCALE.H> LOCALIZATION This compiler defaults to the C locale and does not support any other locales; therefore it does not support the header file locale.h. The following would normally be found in this file: * * * * * * * * * * struct lconv NULL LC_ALL LC_COLLATE LC_CTYPE LC_MONETARY LC_NUMERIC LC_TIME localeconv setlocale (c) 2008 Microchip Technology Inc. DS51456E-page 31 16-Bit Language Tools Libraries 2.9 <SETJMP.H> NON-LOCAL JUMPS The header file setjmp.h consists of a type, a macro and a function that allow control transfers to occur that bypass the normal function call and return process. jmp_buf Description: A type that is an array used by setjmp and longjmp to save and restore the program environment. Include: <setjmp.h> Prototype: typedef int jmp_buf[_NSETJMP]; Remarks: _NSETJMP is defined as 16 + 2 that represents 16 registers and a 32-bit return address. setjmp Description: A macro that saves the current state of the program for later use by longjmp. Include: <setjmp.h> Prototype: #define setjmp(jmp_buf env) Argument: env variable where environment is stored Return Value: If the return is from a direct call, setjmp returns zero. If the return is from a call to longjmp, setjmp returns a non-zero value. Note: If the argument val from longjmp is 0, setjmp returns 1. Example: See longjmp. longjmp Description: A function that restores the environment saved by setjmp. Include: <setjmp.h> Prototype: void longjmp(jmp_buf env, int val); Arguments: env variable where environment is stored val value to be returned to setjmp call. Remarks: DS51456E-page 32 The value parameter val should be non-zero. If longjmp is invoked from a nested signal handler (that is, invoked as a result of a signal raised during the handling of another signal), the behavior is undefined. (c) 2008 Microchip Technology Inc. Standard C Libraries 2.10 <SIGNAL.H> SIGNAL HANDLING The header file signal.h consists of a type, several macros and two functions that specify how the program handles signals while it is executing. A signal is a condition that may be reported during the program execution. Signals are synchronous, occurring under software control via the raise function. A signal may be handled by: * Default handling (SIG_DFL); the signal is treated as a fatal error and execution stops * Ignoring the signal (SIG_IGN); the signal is ignored and control is returned to the user application * Handling the signal with a function designated via signal. By default all signals are handled by the default handler, which is identified by SIG_DFL. The type sig_atomic_t is an integer type that the program access atomically. When this type is used with the keyword volatile, the signal handler can share the data objects with the rest of the program. sig_atomic_t Description: A type used by a signal handler Include: <signal.h> Prototype: typedef int sig_atomic_t; SIG_DFL Description: Used as the second argument and/or the return value for signal to specify that the default handler should be used for a specific signal. Include: <signal.h> SIG_ERR Description: Used as the return value for signal when it cannot complete a request due to an error. Include: <signal.h> SIG_IGN Description: Used as the second argument and/or the return value for signal to specify that the signal should be ignored. Include: <signal.h> (c) 2008 Microchip Technology Inc. DS51456E-page 33 16-Bit Language Tools Libraries SIGABRT Description: Name for the abnormal termination signal. Include: <signal.h> Prototype: #define SIGABRT Remarks: SIGABRT represents an abnormal termination signal and is used in conjunction with raise or signal. The default raise behavior (action identified by SIG_DFL) is to output to the standard error stream: abort - terminating See the example accompanying signal to see general usage of signal names and signal handling. Example: #include <signal.h> /* for raise, SIGABRT */ #include <stdio.h> /* for printf */ int main(void) { raise(SIGABRT); printf("Program never reaches here."); } Output: ABRT Explanation: ABRT stands for "abort". SIGFPE Description: Signals floating-point error such as for division by zero or result out of range. Include: <signal.h> Prototype: #define SIGFPE Remarks: SIGFPE is used as an argument for raise and/or signal. When used, the default behavior is to print an arithmetic error message and terminate the calling program. This may be overridden by a user function that defines the signal handler actions. See signal for an example of a user defined function. Example: #include <signal.h> /* for raise, SIGFPE */ #include <stdio.h> /* for printf */ int main(void) { raise(SIGFPE); printf("Program never reaches here"); } Output: FPE Explanation: FPE stands for "floating-point error". DS51456E-page 34 (c) 2008 Microchip Technology Inc. Standard C Libraries SIGILL Description: Signals illegal instruction. Include: <signal.h> Prototype: #define SIGILL Remarks: SIGILL is used as an argument for raise and/or signal. When used, the default behavior is to print an invalid executable code message and terminate the calling program. This may be overridden by a user function that defines the signal handler actions. See signal for an example of a user defined function. Example: #include <signal.h> /* for raise, SIGILL */ #include <stdio.h> /* for printf */ int main(void) { raise(SIGILL); printf("Program never reaches here"); } Output: ILL Explanation: ILL stands for "illegal instruction". SIGINT Description: Interrupt signal. Include: <signal.h> Prototype: #define SIGINT Remarks: SIGINT is used as an argument for raise and/or signal. When used, the default behavior is to print an interruption message and terminate the calling program. This may be overridden by a user function that defines the signal handler actions. See signal for an example of a user defined function. Example: #include <signal.h> /* for raise, SIGINT */ #include <stdio.h> /* for printf */ int main(void) { raise(SIGINT); printf("Program never reaches here."); } Output: INT Explanation: INT stands for "interruption". (c) 2008 Microchip Technology Inc. DS51456E-page 35 16-Bit Language Tools Libraries SIGSEGV Description: Signals invalid access to storage. Include: <signal.h> Prototype: #define SIGSEGV Remarks: SIGSEGV is used as an argument for raise and/or signal. When used, the default behavior is to print an invalid storage request message and terminate the calling program. This may be overridden by a user function that defines the signal handler actions. See signal for an example of a user defined function. Example: #include <signal.h> /* for raise, SIGSEGV */ #include <stdio.h> /* for printf */ int main(void) { raise(SIGSEGV); printf("Program never reaches here."); } Output: SEGV Explanation: SEGV stands for "invalid storage access". SIGTERM Description: Signals a termination request Include: <signal.h> Prototype: #define SIGTERM Remarks: SIGTERM is used as an argument for raise and/or signal. When used, the default behavior is to print a termination request message and terminate the calling program. This may be overridden by a user function that defines the signal handler actions. See signal for an example of a user defined function. Example: #include <signal.h> /* for raise, SIGTERM */ #include <stdio.h> /* for printf */ int main(void) { raise(SIGTERM); printf("Program never reaches here."); } Output: TERM Explanation: TERM stands for "termination request". DS51456E-page 36 (c) 2008 Microchip Technology Inc. Standard C Libraries raise Description: Reports a synchronous signal. Include: <signal.h> Prototype: int raise(int sig); Argument: sig signal name Return Value: Returns a 0 if successful; otherwise, returns a non-zero value. Remarks: raise sends the signal identified by sig to the executing program. Example: #include <signal.h> /* /* #include <stdlib.h> /* #include <stdio.h> /* #include <p30f6014.h> /* for raise, signal, SIGILL, SIG_DFL for div, div_t for printf for INTCON1bits */ */ */ */ */ void __attribute__((__interrupt__)) _MathError(void) { raise(SIGILL); INTCON1bits.MATHERR = 0; } void illegalinsn(int idsig) { printf("Illegal instruction executed\n"); exit(1); } int main(void) { int x, y; div_t z; signal(SIGILL, illegalinsn); x = 7; y = 0; z = div(x, y); printf("Program never reaches here"); } Output: Illegal instruction executed Explanation: This example requires the linker script p30f6014.gld. There are three parts to this example. First, an interrupt handler is written for the interrupt vector _MathError to handle a math error by sending an illegal instruction signal (SIGILL) to the executing program. The last statement in the interrupt handler clears the exception flag. Second, the function illegalinsn will print an error message and call exit. Third, in main, signal (SIGILL, illegalinsn) sets the handler for SIGILL to the function illegalinsn. When a math error occurs, due to a divide by zero, the _MathError interrupt vector is called, which in turn will raise a signal that will call the handler function for SIGILL, which is the function illegalinsn. Thus error messages are printed and the program is terminated. (c) 2008 Microchip Technology Inc. DS51456E-page 37 16-Bit Language Tools Libraries signal Description: Controls interrupt signal handling. Include: <signal.h> Prototype: void (*signal(int sig, void(*func)(int)))(int); Arguments: sig signal name func function to be executed Return Value: Returns the previous value of func. Example: #include <signal.h> /* /* /* #include <stdio.h> /* for signal, raise, */ SIGINT, SIGILL, */ SIG_IGN, and SIGFPE */ for printf */ /* Signal handler function */ void mysigint(int id) { printf("SIGINT received\n"); } int main(void) { /* Override default with user defined function */ signal(SIGINT, mysigint); raise(SIGINT); /* Ignore signal handler */ signal(SIGILL, SIG_IGN); raise(SIGILL); printf("SIGILL was ignored\n"); /* Use default signal handler */ raise(SIGFPE); printf("Program never reaches here."); } Output: SIGINT received SIGILL was ignored FPE Explanation: The function mysigint is the user-defined signal handler for SIGINT. Inside the main program, the function signal is called to set up the signal handler (mysigint) for the signal SIGINT that will override the default actions. The function raise is called to report the signal SIGINT. This causes the signal handler for SIGINT to use the user-defined function (mysigint) as the signal handler so it prints the "SIGINT received" message. Next, the function signal is called to set up the signal handler SIG_IGN for the signal SIGILL. The constant SIG_IGN is used to indicate the signal should be ignored. The function raise is called to report the signal SIGILL that is ignored. The function raise is called again to report the signal SIGFPE. Since there is no user defined function for SIGFPE, the default signal handler is used so the message "FPE" is printed (which stands for "arithmetic error - terminating"). Then the calling program is terminated. The printf statement is never reached. DS51456E-page 38 (c) 2008 Microchip Technology Inc. Standard C Libraries 2.11 <STDARG.H> VARIABLE ARGUMENT LISTS The header file stdarg.h supports functions with variable argument lists. This allows functions to have arguments without corresponding parameter declarations. There must be at least one named argument. The variable arguments are represented by ellipses (...). An object of type va_list must be declared inside the function to hold the arguments. va_start will initialize the variable to an argument list, va_arg will access the argument list, and va_end will end the use of the argument. va_list Description: The type va_list declares a variable that will refer to each argument in a variable-length argument list. Include: <stdarg.h> Example: See va_arg. va_arg Description: Gets the current argument Include: <stdarg.h> Prototype: #define va_arg(va_list ap, Ty) Argument: ap pointer to list of arguments Ty type of argument to be retrieved Return Value: Returns the current argument Remarks: va_start must be called before va_arg. Example: #include <stdio.h> #include <stdarg.h> /* for printf */ /* for va_arg, va_start, va_list, va_end */ void tprint(const char *fmt, ...) { va_list ap; va_start(ap, fmt); while (*fmt) { switch (*fmt) { (c) 2008 Microchip Technology Inc. DS51456E-page 39 16-Bit Language Tools Libraries va_arg (Continued) case '%': fmt++; if (*fmt == 'd') { int d = va_arg(ap, int); printf("<%d> is an integer\n",d); } else if (*fmt == 's') { char *s = va_arg(ap, char*); printf("<%s> is a string\n", s); } else { printf("%%%c is an unknown format\n", *fmt); } fmt++; break; default: printf("%c is unknown\n", *fmt); fmt++; break; } } va_end(ap); } int main(void) { tprint("%d%s.%c", 83, "This is text.", 'a'); } Output: <83> is an integer <This is text.> is a string . is unknown %c is an unknown format DS51456E-page 40 (c) 2008 Microchip Technology Inc. Standard C Libraries va_end Description: Ends the use of ap. Include: <stdarg.h> Prototype: #define va_end(va_list ap) Argument: ap Remarks: After a call to va_end, the argument list pointer ap is considered to be invalid. Further calls to va_arg should not be made until the next va_start. In the 16-bit compiler, va_end does nothing, so this call is not necessary but should be used for readability and portability. Example: See va_arg. pointer to list of arguments va_start Description: Sets the argument pointer ap to first optional argument in the variable-length argument list Include: <stdarg.h> Prototype: #define va_start(va_list ap, last_arg) Argument: ap pointer to list of arguments last_arg last named argument before the optional arguments Example: 2.12 See va_arg. <STDDEF.H> COMMON DEFINITIONS The header file stddef.h consists of several types and macros that are of general use in programs. ptrdiff_t Description: The type of the result of subtracting two pointers. Include: <stddef.h> size_t Description: The type of the result of the sizeof operator. Include: <stddef.h> wchar_t Description: A type that holds a wide character value. Include: <stddef.h> NULL Description: The value of a null pointer constant. Include: <stddef.h> (c) 2008 Microchip Technology Inc. DS51456E-page 41 16-Bit Language Tools Libraries offsetof Description: Gives the offset of a structure member from the beginning of the structure. Include: <stddef.h> Prototype: #define offsetof(T, mbr) Arguments: T name of structure mbr name of member in structure T Return Value: Returns the offset in bytes of the specified member (mbr) from the beginning of the structure. Remarks: The macro offsetof is undefined for bitfields. An error message will occur if bitfields are used. Example: #include <stddef.h> /* for offsetof */ #include <stdio.h> /* for printf */ struct info { char item1[5]; int item2; char item3; float item4; }; int main(void) { printf("Offset of item1 offsetof(struct printf("Offset of item2 offsetof(struct printf("Offset of item3 offsetof(struct printf("Offset of item4 offsetof(struct } Output: Offset Offset Offset Offset of of of of item1 item2 item3 item4 = = = = = %d\n", info,item1)); = %d\n", info,item2)); = %d\n", info,item3)); = %d\n", info,item4)); 0 6 8 10 Explanation: This program shows the offset in bytes of each structure member from the start of the structure. Although item1 is only 5 bytes (char item1[5]), padding is added so the address of item2 falls on an even boundary. The same occurs with item3; it is 1 byte (char item3) with 1 byte of padding. DS51456E-page 42 (c) 2008 Microchip Technology Inc. Standard C Libraries 2.13 <STDIO.H> INPUT AND OUTPUT The header file stdio.h consists of types, macros and functions that provide support to perform input and output operations on files and streams. When a file is opened it is associated with a stream. A stream is a pipeline for the flow of data into and out of files. Because different systems use different properties, the stream provides more uniform properties to allow reading and writing of the files. Streams can be text streams or binary streams. Text streams consist of a sequence of characters divided into lines. Each line is terminated with a newline (`\n') character. The characters may be altered in their internal representation, particularly in regards to line endings. Binary streams consist of sequences of bytes of information. The bytes transmitted to the binary stream are not altered. There is no concept of lines - the file is just a series of bytes. At start-up three streams are automatically opened: stdin, stdout, and stderr. stdin provides a stream for standard input, stdout is standard output and stderr is the standard error. Additional streams may be created with the fopen function. See fopen for the different types of file access that are permitted. These access types are used by fopen and freopen. The type FILE is used to store information about each opened file stream. It includes such things as error indicators, end-of-file indicators, file position indicators, and other internal status information needed to control a stream. Many functions in the stdio use FILE as an argument. There are three types of buffering: unbuffered, line buffered and fully buffered. Unbuffered means a character or byte is transferred one at a time. Line buffered collects and transfers an entire line at a time (i.e., the newline character indicates the end of a line). Fully buffered allows blocks of an arbitrary size to be transmitted. The functions setbuf and setvbuf control file buffering. The stdio.h file also contains functions that use input and output formats. The input formats, or scan formats, are used for reading data. Their descriptions can be found under scanf, but they are also used by fscanf and sscanf. The output formats, or print formats, are used for writing data. Their descriptions can be found under printf. These print formats are also used by fprintf, sprintf, vfprintf, vprintf and vsprintf. 2.13.1 Compiler Options Certain compiler options may affect how standard I/O performs. In an effort to provide a more tailored version of the formatted I/O routines, the tool chain may convert a call to a printf or scanf style function to a different call. The options are summarized below: *The -msmart-io option, when enabled, will attempt to convert printf, scanf and other functions that use the input output formats to an integer only variant. The functionality is the same as that of the C standard forms, minus the support for floating-point output. -msmart-io=0 disables this feature and no conversion will take place. -msmart-io=1 or -msmart-io (the default) will convert a function call if it can be proven that an I/O function will never be presented with a floating-point conversion. -msmart-io=2 is more optimistic than the default and will assume that non-constant format strings or otherwise unknown format strings will not contain a floating-point format. In the event that -msmart-io=2 is used with a floating-point format, the format letter will appear as literal text and its corresponding argument will not be consumed. (c) 2008 Microchip Technology Inc. DS51456E-page 43 16-Bit Language Tools Libraries *-fno-short-double will cause the compiler to generate calls to formatted I/O routines that support double as if it were a long double type. Mixing modules compiled with these options may result in a larger executable size, or incorrect execution if large and small double-sized data is shared across modules. 2.13.2 Customizing STDIO The standard I/O relies on helper functions described in Chapter 4. "Standard C Libraries - Support Functions". These functions include read(), write(), open(), and close() which are called to read, write, open or close handles that are associated with standard I/O FILE pointers. The sources for these libraries are provided for you to customize as you wish. The simplest way to redirect standard I/O to the pheripheral of your choice is to select one of the default handles already in use. Also, you could open files with a specific name, via fopen(), by rewriting open() to return a new handle to be recognized by read() or write(), as appropriate. If only a specific peripheral is required, then you could associate handle 1 == stdout, or 2 == stderr, to another peripheral by writing the correct code to talk to the interested peripheral. A complete generic solution might be: /* should be in a header file */ enum my_handles { handle_stdin, handle_stdout, handle_stderr, handle_can1, handle_can2, handle_spi1, handle_spi2, }; int __attribute__((__weak__, __section__(".libc"))) open(const char *name, int access, int mode) { switch (name[0]) { case 'i' : return handle_stdin; case 'o' : return handle_stdout; case 'e' : return handle_stderr; case 'c' : return handle_can1; case 'C' : return handle_can2; case 's' : return handle_spi1; case 'S' : return handle_spi2; default: return handle_stderr; } } Single letters were used in this example because they are faster to check and use less memory. However, if memory is not an issue, you could use strcmp to compare full names. In write(), you would write: write(int handle, void *buffer, unsigned int len) { int i; volatile UxMODEBITS *umode = &U1MODEbits; volatile UxSTABITS *ustatus = &U1STAbits; volatile unsigned int *txreg = &U1TXREG; volatile unsigned int *brg = &U1BRG; switch (handle) DS51456E-page 44 (c) 2008 Microchip Technology Inc. Standard C Libraries { default: case 0: case 1: case 2: if ((__C30_UART != 1) && (&U2BRG)) umode = &U2MODEbits; ustatus = &U2STAbits; txreg = &U2TXREG; brg = &U2BRG; } if ((umode->UARTEN) == 0) { *brg = 0; umode->UARTEN = 1; } if ((ustatus->UTXEN) == 0) { ustatus->UTXEN = 1; } for (i = len; i; --i) { while ((ustatus->TRMT) ==0); *txreg = *(char*)buffer++; } break; case handle_can1: /* code to support break; case handle_can2: /* code to support break; case handle_spi1: /* code to support break; case handle_spi2: /* code to support break; } return(len); { can1 */ can2 */ spi1 */ spi2 */ } where you would fill in the appropriate code as specified in the comments. Now you can use the generic C STDIO features to write to another port: FILE *can1 = fopen("c","w"); fprintf(can1,"This will be output through the can\n"); 2.13.3 STDIO Functions FILE Description: Stores information for a file stream. Include: <stdio.h> fpos_t Description: Type of a variable used to store a file position. Include: <stdio.h> (c) 2008 Microchip Technology Inc. DS51456E-page 45 16-Bit Language Tools Libraries size_t Description: The result type of the sizeof operator. Include: <stdio.h> _IOFBF Description: Indicates full buffering. Include: <stdio.h> Remarks: Used by the function setvbuf. _IOLBF Description: Indicates line buffering. Include: <stdio.h> Remarks: Used by the function setvbuf. _IONBF Description: Indicates no buffering. Include: <stdio.h> Remarks: Used by the function setvbuf. BUFSIZ Description: Defines the size of the buffer used by the function setbuf. Include: <stdio.h> Value: 512 EOF Description: A negative number indicating the end-of-file has been reached or to report an error condition. Include: <stdio.h> Remarks: If an end-of-file is encountered, the end-of-file indicator is set. If an error condition is encountered, the error indicator is set. Error conditions include write errors and input or read errors. FILENAME_MAX Description: Maximum number of characters in a filename including the null terminator. Include: <stdio.h> Value: 260 FOPEN_MAX Description: DS51456E-page 46 Defines the maximum number of files that can be simultaneously open (c) 2008 Microchip Technology Inc. Standard C Libraries FOPEN_MAX (Continued) Include: <stdio.h> Value: 8 Remarks: stderr, stdin and stdout are included in the FOPEN_MAX count. L_tmpnam Description: Defines the number of characters for the longest temporary filename created by the function tmpnam. Include: <stdio.h> Value: 16 Remarks: L_tmpnam is used to define the size of the array used by tmpnam. NULL Description: The value of a null pointer constant Include: <stdio.h> SEEK_CUR Description: Indicates that fseek should seek from the current position of the file pointer Include: <stdio.h> Example: See example for fseek. (c) 2008 Microchip Technology Inc. DS51456E-page 47 16-Bit Language Tools Libraries SEEK_END Description: Indicates that fseek should seek from the end of the file. Include: <stdio.h> Example: See example for fseek. SEEK_SET Description: Indicates that fseek should seek from the beginning of the file. Include: <stdio.h> Example: See example for fseek. stderr Description: File pointer to the standard error stream. Include: <stdio.h> stdin Description: File pointer to the standard input stream. Include: <stdio.h> stdout Description: File pointer to the standard output stream. Include: <stdio.h> TMP_MAX DS51456E-page 48 Description: The maximum number of unique filenames the function tmpnam can generate. Include: <stdio.h> Value: 32 (c) 2008 Microchip Technology Inc. Standard C Libraries clearerr Description: Resets the error indictor for the stream Include: <stdio.h> Prototype: void clearerr(FILE *stream); Argument: stream Remarks: The function clears the end-of-file and error indicators for the given stream (i.e., feof and ferror will return false after the function clearerr is called). stream to reset error indicators Example: /* This program tries to write to a file that is /* readonly. This causes the error indicator to /* be set. The function ferror is used to check /* the error indicator. The function clearerr is /* used to reset the error indicator so the next /* time ferror is called it will not report an /* error. #include <stdio.h> /* for ferror, clearerr, */ /* printf, fprintf, fopen,*/ /* fclose, FILE, NULL */ */ */ */ */ */ */ */ int main(void) { FILE *myfile; if ((myfile = fopen("sampclearerr.c", "r")) == NULL) printf("Cannot open file\n"); else { fprintf(myfile, "Write this line to the " "file.\n"); if (ferror(myfile)) printf("Error\n"); else printf("No error\n"); clearerr(myfile); if (ferror(myfile)) printf("Still has Error\n"); else printf("Error indicator reset\n"); fclose(myfile); } } Output: Error Error indicator reset (c) 2008 Microchip Technology Inc. DS51456E-page 49 16-Bit Language Tools Libraries fclose Description: Close a stream. Include: <stdio.h> Prototype: int fclose(FILE *stream); Argument: stream Return Value: Returns 0 if successful; otherwise, returns EOF if any errors were detected. Remarks: fclose writes any buffered output to the file. Example: #include <stdio.h> /* for fopen, fclose, */ /* printf,FILE, NULL, EOF */ pointer to the stream to close int main(void) { FILE *myfile1, *myfile2; int y; if ((myfile1 = fopen("afile1", "w+")) == NULL) printf("Cannot open afile1\n"); else { printf("afile1 was opened\n"); y = fclose(myfile1); if (y == EOF) printf("afile1 was not closed\n"); else printf("afile1 was closed\n"); } } Output: afile1 was opened afile1 was closed DS51456E-page 50 (c) 2008 Microchip Technology Inc. Standard C Libraries feof Description: Tests for end-of-file Include: <stdio.h> Prototype: int feof(FILE *stream); Argument: stream Return Value: Returns non-zero if stream is at the end-of-file; otherwise, returns zero. Example: #include <stdio.h> /* for feof, fgetc, fputc, */ /* fopen, fclose, FILE, */ /* NULL */ stream to check for end-of-file int main(void) { FILE *myfile; int y = 0; if( (myfile = fopen( "afile.txt", "rb" )) == NULL ) printf( "Cannot open file\n" ); else { for (;;) { y = fgetc(myfile); if (feof(myfile)) break; fputc(y, stdout); } fclose( myfile ); } } Input: Contents of afile.txt (used as input): This is a sentence. Output: This is a sentence. (c) 2008 Microchip Technology Inc. DS51456E-page 51 16-Bit Language Tools Libraries ferror Description: Tests if error indicator is set. Include: <stdio.h> Prototype: int ferror(FILE *stream); Argument: stream Return Value: Returns a non-zero value if error indicator is set; otherwise, returns a zero. Example: /* /* /* /* /* /* /* pointer to FILE structure This program tries to write to a file that is readonly. This causes the error indicator to be set. The function ferror is used to check the error indicator and find the error. The function clearerr is used to reset the error indicator so the next time ferror is called it will not report an error. #include <stdio.h> /* /* /* /* for ferror, clearerr, printf, fprintf, fopen, fclose, FILE, NULL */ */ */ */ */ */ */ */ */ */ */ int main(void) { FILE *myfile; if ((myfile = fopen("sampclearerr.c", "r")) == NULL) printf("Cannot open file\n"); else { fprintf(myfile, "Write this line to the " "file.\n"); if (ferror(myfile)) printf("Error\n"); else printf("No error\n"); clearerr(myfile); if (ferror(myfile)) printf("Still has Error\n"); else printf("Error indicator reset\n"); fclose(myfile); } } Output: Error Error indicator reset DS51456E-page 52 (c) 2008 Microchip Technology Inc. Standard C Libraries fflush Description: Flushes the buffer in the specified stream. Include: <stdio.h> Prototype: int fflush(FILE *stream); Argument: stream Return Value: Returns EOF if a write error occurs; otherwise, returns zero for success. Remarks: If stream is a null pointer, all output buffers are written to files. fflush has no effect on an unbuffered stream. pointer to the stream to flush. fgetc Description: Get a character from a stream Include: <stdio.h> Prototype: int fgetc(FILE *stream); Argument: stream Return Value: Returns the character read or EOF if a read error occurs or end-of-file is reached. Remarks: The function reads the next character from the input stream, advances the file-position indicator and returns the character as an unsigned char converted to an int. Example: #include <stdio.h> /* for fgetc, printf, */ /* fclose, FILE, */ /* NULL, EOF */ pointer to the open stream int main(void) { FILE *buf; char y; if ((buf = fopen("afile.txt", "r")) == NULL) printf("Cannot open afile.txt\n"); else { y = fgetc(buf); while (y != EOF) { printf("%c|", y); y = fgetc(buf); } fclose(buf); } } Input: Contents of afile.txt (used as input): Short Longer string Output: S|h|o|r|t| |L|o|n|g|e|r| |s|t|r|i|n|g| | (c) 2008 Microchip Technology Inc. DS51456E-page 53 16-Bit Language Tools Libraries fgetpos Description: Gets the stream's file position. Include: <stdio.h> Prototype: int fgetpos(FILE *stream, fpos_t *pos); Arguments: stream target stream pos position-indicator storage Return Value: Returns 0 if successful; otherwise, returns a non-zero value. Remarks: The function stores the file-position indicator for the given stream in *pos if successful, otherwise, fgetpos sets errno. Example: /* /* /* /* /* /* /* This program opens a file and reads bytes at */ several different locations. The fgetpos */ function notes the 8th byte. 21 bytes are */ read then 18 bytes are read. Next the */ fsetpos function is set based on the */ fgetpos position and the previous 21 bytes */ are reread. */ #include <stdio.h> /* /* /* /* for fgetpos, fread, printf, fopen, fclose, FILE, NULL, perror, fpos_t, sizeof */ */ */ */ int main(void) { FILE *myfile; fpos_t pos; char buf[25]; if ((myfile = fopen("sampfgetpos.c", "rb")) == NULL) printf("Cannot open file\n"); else { fread(buf, sizeof(char), 8, myfile); if (fgetpos(myfile, &pos) != 0) perror("fgetpos error"); else { fread(buf, sizeof(char), 21, myfile); printf("Bytes read: %.21s\n", buf); fread(buf, sizeof(char), 18, myfile); printf("Bytes read: %.18s\n", buf); } if (fsetpos(myfile, &pos) != 0) perror("fsetpos error"); fread(buf, sizeof(char), 21, myfile); printf("Bytes read: %.21s\n", buf); fclose(myfile); } } Output: Bytes read: program opens a file Bytes read: and reads bytes at Bytes read: program opens a file DS51456E-page 54 (c) 2008 Microchip Technology Inc. Standard C Libraries fgets Description: Get a string from a stream Include: <stdio.h> Prototype: char *fgets(char *s, int n, FILE *stream); Arguments: s pointer to the storage string n maximum number of characters to read stream pointer to the open stream. Return Value: Returns a pointer to the string s if successful; otherwise, returns a null pointer Remarks: The function reads characters from the input stream and stores them into the string pointed to by s until it has read n-1 characters, stores a newline character or sets the end-of-file or error indicators. If any characters were stored, a null character is stored immediately after the last read character in the next element of the array. If fgets sets the error indicator, the array contents are indeterminate. Example: #include <stdio.h> /* for fgets, printf, */ /* fopen, fclose, */ /* FILE, NULL */ #define MAX 50 int main(void) { FILE *buf; char s[MAX]; if ((buf = fopen("afile.txt", "r")) == NULL) printf("Cannot open afile.txt\n"); else { while (fgets(s, MAX, buf) != NULL) { printf("%s|", s); } fclose(buf); } } Input: Contents of afile.txt (used as input): Short Longer string Output: Short |Longer string | (c) 2008 Microchip Technology Inc. DS51456E-page 55 16-Bit Language Tools Libraries fopen Description: Opens a file. Include: <stdio.h> Prototype: FILE *fopen(const char *filename, const char *mode); Arguments: filename name of the file mode type of access permitted Return Value: Returns a pointer to the open stream. If the function fails a null pointer is returned. Remarks: Following are the types of file access: r- opens an existing text file for reading wopens an empty text file for writing. (An existing file will be overwritten.) aopens a text file for appending. (A file is created if it doesn't exist.) rb - opens an existing binary file for reading. wb opens an empty binary file for writing. (An existing file will be overwritten.) ab opens a binary file for appending. (A file is created if it doesn't exist.) r+ - opens an existing text file for reading and writing. w+ opens an empty text file for reading and writing. (An existing file will be overwritten.) a+ opens a text file for reading and appending. (A file is created if it doesn't exist.) r+b or rb+ - opens an existing binary file for reading and writing. w+b or wb+ - opens an empty binary file for reading and writing. (An existing file will be overwritten.) a+b or ab+ - opens a binary file for reading and appending. (A file is created if it doesn't exist.) Example: #include <stdio.h> /* for fopen, fclose, */ /* printf, FILE, */ /* NULL, EOF */ int main(void) { FILE *myfile1, *myfile2; int y; DS51456E-page 56 (c) 2008 Microchip Technology Inc. Standard C Libraries fopen (Continued) if ((myfile1 = fopen("afile1", "r")) == NULL) printf("Cannot open afile1\n"); else { printf("afile1 was opened\n"); y = fclose(myfile1); if (y == EOF) printf("afile1 was not closed\n"); else printf("afile1 was closed\n"); } if ((myfile1 = fopen("afile1", "w+")) == NULL) printf("Second try, cannot open afile1\n"); else { printf("Second try, afile1 was opened\n"); y = fclose(myfile1); if (y == EOF) printf("afile1 was not closed\n"); else printf("afile1 was closed\n"); } if ((myfile2 = fopen("afile2", "w+")) == NULL) printf("Cannot open afile2\n"); else { printf("afile2 was opened\n"); y = fclose(myfile2); if (y == EOF) printf("afile2 was not closed\n"); else printf("afile2 was closed\n"); } } Output: Cannot Second afile1 afile2 afile2 open afile1 try, afile1 was opened was closed was opened was closed Explanation: afile1 must exist before it can be opened for reading (r) or the fopen function will fail. If the fopen function opens a file for writing (w+) it does not have to already exist. If it doesn't exist, it will be created and then opened. (c) 2008 Microchip Technology Inc. DS51456E-page 57 16-Bit Language Tools Libraries fprintf Description: Prints formatted data to a stream. Include: <stdio.h> Prototype: int fprintf(FILE *stream, const char *format, ...); Arguments: stream pointer to the stream in which to output data format format control string ... optional arguments Return Value: Returns number of characters generated or a negative number if an error occurs. Remarks: The format argument has the same syntax and use that it has in print. Example: #include <stdio.h> /* for fopen, fclose, */ /* fprintf, printf, */ /* FILE, NULL */ int main(void) { FILE *myfile; int y; char s[]="Print this string"; int x = 1; char a = '\n'; if ((myfile = fopen("afile", "w")) == NULL) printf("Cannot open afile\n"); else { y = fprintf(myfile, "%s %d time%c", s, x, a); printf("Number of characters printed " "to file = %d",y); fclose(myfile); } } Output: Number of characters printed to file = 25 Contents of afile: Print this string 1 time DS51456E-page 58 (c) 2008 Microchip Technology Inc. Standard C Libraries fputc Description: Puts a character to the stream. Include: <stdio.h> Prototype: int fputc(int c, FILE *stream); Arguments: c character to be written stream pointer to the open stream Return Value: Returns the character written or EOF if a write error occurs. Remarks: The function writes the character to the output stream, advances the file-position indicator and returns the character as an unsigned char converted to an int. Example: #include <stdio.h> /* for fputc, EOF, stdout */ int main(void) { char *y; char buf[] = "This is text\n"; int x; x = 0; for (y = buf; (x != EOF) && (*y != '\0'); y++) { x = fputc(*y, stdout); fputc('|', stdout); } } Output: T|h|i|s| |i|s| |t|e|x|t| | fputs Description: Puts a string to the stream. Include: <stdio.h> Prototype: int fputs(const char *s, FILE *stream); Arguments: s string to be written stream pointer to the open stream Return Value: Returns a non-negative value if successful; otherwise, returns EOF. Remarks: The function writes characters to the output stream up to but not including the null character. Example: #include <stdio.h> /* for fputs, stdout */ int main(void) { char buf[] = "This is text\n"; fputs(buf,stdout); fputs("|",stdout); } Output: This is text | (c) 2008 Microchip Technology Inc. DS51456E-page 59 16-Bit Language Tools Libraries fread Description: Reads data from the stream. Include: <stdio.h> Prototype: size_t fread(void *ptr, size_t size, size_t nelem, FILE *stream); Arguments: ptr pointer to the storage buffer size size of item nelem maximum number of items to be read stream pointer to the stream Return Value: Returns the number of complete elements read up to nelem whose size is specified by size. Remarks: The function reads characters from a given stream into the buffer pointed to by ptr until the function stores size * nelem characters or sets the end-of-file or error indicator. fread returns n/size where n is the number of characters it read. If n is not a multiple of size, the value of the last element is indeterminate. If the function sets the error indicator, the file-position indicator is indeterminate. Example: #include <stdio.h> /* for fread, fwrite, */ /* printf, fopen, fclose, */ /* sizeof, FILE, NULL */ int main(void) { FILE *buf; int x, numwrote, numread; double nums[10], readnums[10]; if ((buf = fopen("afile.out", "w+")) != NULL) { for (x = 0; x < 10; x++) { nums[x] = 10.0/(x + 1); printf("10.0/%d = %f\n", x+1, nums[x]); } numwrote = fwrite(nums, sizeof(double), 10, buf); printf("Wrote %d numbers\n\n", numwrote); fclose(buf); } else printf("Cannot open afile.out\n"); DS51456E-page 60 (c) 2008 Microchip Technology Inc. Standard C Libraries fread (Continued) if ((buf = fopen("afile.out", "r+")) != NULL) { numread = fread(readnums, sizeof(double), 10, buf); printf("Read %d numbers\n", numread); for (x = 0; x < 10; x++) { printf("%d * %f = %f\n", x+1, readnums[x], (x + 1) * readnums[x]); } fclose(buf); } else printf("Cannot open afile.out\n"); } Output: 10.0/1 = 10.000000 10.0/2 = 5.000000 10.0/3 = 3.333333 10.0/4 = 2.500000 10.0/5 = 2.000000 10.0/6 = 1.666667 10.0/7 = 1.428571 10.0/8 = 1.250000 10.0/9 = 1.111111 10.0/10 = 1.000000 Wrote 10 numbers Read 10 numbers 1 * 10.000000 = 10.000000 2 * 5.000000 = 10.000000 3 * 3.333333 = 10.000000 4 * 2.500000 = 10.000000 5 * 2.000000 = 10.000000 6 * 1.666667 = 10.000000 7 * 1.428571 = 10.000000 8 * 1.250000 = 10.000000 9 * 1.111111 = 10.000000 10 * 1.000000 = 10.000000 Explanation: This program uses fwrite to save 10 numbers to a file in binary form. This allows the numbers to be saved in the same pattern of bits as the program is using which provides more accuracy and consistency. Using fprintf would save the numbers as text strings which could cause the numbers to be truncated. Each number is divided into 10 to produce a variety of numbers. Retrieving the numbers with fread to a new array and multiplying them by the original number shows the numbers were not truncated in the save process. (c) 2008 Microchip Technology Inc. DS51456E-page 61 16-Bit Language Tools Libraries freopen Description: Reassigns an existing stream to a new file. Include: <stdio.h> Prototype: FILE *freopen(const char *filename, const char *mode, FILE *stream); Arguments: filename name of the new file mode type of access permitted stream pointer to the currently open stream Return Value: Returns a pointer to the new open file. If the function fails a null pointer is returned. Remarks: The function closes the file associated with the stream as though fclose was called. Then it opens the new file as though fopen was called. freopen will fail if the specified stream is not open. See fopen for the possible types of file access. Example: #include <stdio.h> /* for fopen, freopen, */ /* printf, fclose, */ /* FILE, NULL */ int main(void) { FILE *myfile1, *myfile2; int y; if ((myfile1 = fopen("afile1", "w+")) == NULL) printf("Cannot open afile1\n"); else { printf("afile1 was opened\n"); if ((myfile2 = freopen("afile2", "w+", myfile1)) == NULL) { printf("Cannot open afile2\n"); fclose(myfile1); } else { printf("afile2 was opened\n"); fclose(myfile2); } } } Output: afile1 was opened afile2 was opened Explanation: This program uses myfile2 to point to the stream when freopen is called so if an error occurs, myfile1 will still point to the stream and can be closed properly. If the freopen call is successful, myfile2 can be used to close the stream properly. fscanf DS51456E-page 62 Description: Scans formatted text from a stream. Include: <stdio.h> (c) 2008 Microchip Technology Inc. Standard C Libraries fscanf (Continued) Prototype: int fscanf(FILE *stream, const char *format, ...); Arguments: stream pointer to the open stream from which to read data format format control string ... optional arguments Return Value: Returns the number of items successfully converted and assigned. If no items are assigned, a 0 is returned. EOF is returned if end-of-file is encountered before the first conversion or if an error occurs. Remarks: The format argument has the same syntax and use that it has in scanf. Example: #include <stdio.h> /* /* /* /* for fopen, fscanf, fclose, fprintf, fseek, printf, FILE, NULL, SEEK_SET */ */ */ */ int main(void) { FILE *myfile; char s[30]; int x; char a; if ((myfile = fopen("afile", "w+")) == NULL) printf("Cannot open afile\n"); else { fprintf(myfile, "%s %d times%c", "Print this string", 100, '\n'); fseek(myfile, 0L, SEEK_SET); fscanf(myfile, printf("%s\n", fscanf(myfile, printf("%s\n", fscanf(myfile, printf("%s\n", fscanf(myfile, printf("%d\n", fscanf(myfile, printf("%s\n", fscanf(myfile, printf("%c\n", "%s", s); "%s", s); "%s", s); "%d", x); "%s", s); "%c", a); s); s); s); &x); s); a); fclose(myfile); } } Input: Contents of afile: Print this string 100 times Output: Print this string 100 times (c) 2008 Microchip Technology Inc. DS51456E-page 63 16-Bit Language Tools Libraries fseek Description: Moves file pointer to a specific location. Include: <stdio.h> Prototype: int fseek(FILE *stream, long offset, int mode); Arguments: stream stream in which to move the file pointer. offset value to add to the current position mode type of seek to perform Return Value: Returns 0 if successful; otherwise, returns a non-zero value and set errno. Remarks: mode can be one of the following: SEEK_SET - seeks from the beginning of the file SEEK_CUR - seeks from the current position of the file pointer SEEK_END - seeks from the end of the file Example: #include <stdio.h> /* /* /* /* /* for fseek, fgets, printf, fopen, fclose, FILE, NULL, perror, SEEK_SET, SEEK_CUR, SEEK_END */ */ */ */ */ int main(void) { FILE *myfile; char s[70]; int y; myfile = fopen("afile.out", "w+"); if (myfile == NULL) printf("Cannot open afile.out\n"); else { fprintf(myfile, "This is the beginning, " "this is the middle and " "this is the end."); y = fseek(myfile, 0L, SEEK_SET); if (y) perror("Fseek failed"); else { fgets(s, 22, myfile); printf("\"%s\"\n\n", s); } y = fseek(myfile, 2L, SEEK_CUR); if (y) perror("Fseek failed"); else { fgets(s, 70, myfile); printf("\"%s\"\n\n", s); } DS51456E-page 64 (c) 2008 Microchip Technology Inc. Standard C Libraries fseek (Continued) y = fseek(myfile, -16L, SEEK_END); if (y) perror("Fseek failed"); else { fgets(s, 70, myfile); printf("\"%s\"\n", s); } fclose(myfile); } } Output: "This is the beginning" "this is the middle and this is the end." "this is the end." Explanation: The file afile.out is created with the text, "This is the beginning, this is the middle and this is the end". The function fseek uses an offset of zero and SEEK_SET to set the file pointer to the beginning of the file. fgets then reads 22 characters which are "This is the beginning", and adds a null character to the string. Next, fseek uses an offset of two and SEEK_CURRENT to set the file pointer to the current position plus two (skipping the comma and space). fgets then reads up to the next 70 characters. The first 39 characters are "this is the middle and this is the end". It stops when it reads EOF and adds a null character to the string. FInally, fseek uses an offset of negative 16 characters and SEEK_END to set the file pointer to 16 characters from the end of the file. fgets then reads up to 70 characters. It stops at the EOF after reading 16 characters "this is the end". and adds a null character to the string. fsetpos Description: Sets the stream's file position. Include: <stdio.h> Prototype: int fsetpos(FILE *stream, const fpos_t *pos); Arguments: stream target stream pos to fgetpos position-indicator storage as returned by an earlier call Return Value: Returns 0 if successful; otherwise, returns a non-zero value. Remarks: The function sets the file-position indicator for the given stream in *pos if successful; otherwise, fsetpos sets errno. (c) 2008 Microchip Technology Inc. DS51456E-page 65 16-Bit Language Tools Libraries fsetpos (Continued) Example: /* /* /* /* /* /* /* This program opens a file and reads bytes at */ several different locations. The fgetpos */ function notes the 8th byte. 21 bytes are */ read then 18 bytes are read. Next the */ fsetpos function is set based on the */ fgetpos position and the previous 21 bytes */ are reread. */ #include <stdio.h> /* /* /* /* for fgetpos, fread, printf, fopen, fclose, FILE, NULL, perror, fpos_t, sizeof */ */ */ */ int main(void) { FILE *myfile; fpos_t pos; char buf[25]; if ((myfile = fopen("sampfgetpos.c", "rb")) == NULL) printf("Cannot open file\n"); else { fread(buf, sizeof(char), 8, myfile); if (fgetpos(myfile, &pos) != 0) perror("fgetpos error"); else { fread(buf, sizeof(char), 21, myfile); printf("Bytes read: %.21s\n", buf); fread(buf, sizeof(char), 18, myfile); printf("Bytes read: %.18s\n", buf); } if (fsetpos(myfile, &pos) != 0) perror("fsetpos error"); fread(buf, sizeof(char), 21, myfile); printf("Bytes read: %.21s\n", buf); fclose(myfile); } } Output: Bytes read: program opens a file Bytes read: and reads bytes at Bytes read: program opens a file DS51456E-page 66 (c) 2008 Microchip Technology Inc. Standard C Libraries ftell Description: Gets the current position of a file pointer. Include: <stdio.h> Prototype: long ftell(FILE *stream); Argument: stream Return Value: Returns the position of the file pointer if successful; otherwise, returns -1. Example: #include <stdio.h> /* /* /* /* stream in which to get the current file position for ftell, fread, */ fprintf, printf, */ fopen, fclose, sizeof, */ FILE, NULL */ int main(void) { FILE *myfile; char s[75]; long y; myfile = fopen("afile.out", "w+"); if (myfile == NULL) printf("Cannot open afile.out\n"); else { fprintf(myfile,"This is a very long sentence " "for input into the file named " "afile.out for testing."); fclose(myfile); if ((myfile = fopen("afile.out", "rb")) != NULL) { printf("Read some characters:\n"); fread(s, sizeof(char), 29, myfile); printf("\t\"%s\"\n", s); y = ftell(myfile); printf("The current position of the " "file pointer is %ld\n", y); fclose(myfile); } } } Output: Read some characters: "This is a very long sentence " The current position of the file pointer is 29 (c) 2008 Microchip Technology Inc. DS51456E-page 67 16-Bit Language Tools Libraries fwrite Description: Writes data to the stream. Include: <stdio.h> Prototype: size_t fwrite(const void *ptr, size_t size, size_t nelem, FILE *stream); Arguments: ptr pointer to the storage buffer size size of item nelem maximum number of items to be read stream pointer to the open stream Return Value: Returns the number of complete elements successfully written, which will be less than nelem only if a write error is encountered. Remarks: The function writes characters to a given stream from a buffer pointed to by ptr up to nelem elements whose size is specified by size. The file position indicator is advanced by the number of characters successfully written. If the function sets the error indicator, the file-position indicator is indeterminate. Example: #include <stdio.h> /* for fread, fwrite, */ /* printf, fopen, fclose, */ /* sizeof, FILE, NULL */ int main(void) { FILE *buf; int x, numwrote, numread; double nums[10], readnums[10]; if ((buf = fopen("afile.out", "w+")) != NULL) { for (x = 0; x < 10; x++) { nums[x] = 10.0/(x + 1); printf("10.0/%d = %f\n", x+1, nums[x]); } numwrote = fwrite(nums, sizeof(double), 10, buf); printf("Wrote %d numbers\n\n", numwrote); fclose(buf); } else printf("Cannot open afile.out\n"); DS51456E-page 68 (c) 2008 Microchip Technology Inc. Standard C Libraries fwrite (Continued) if ((buf = fopen("afile.out", "r+")) != NULL) { numread = fread(readnums, sizeof(double), 10, buf); printf("Read %d numbers\n", numread); for (x = 0; x < 10; x++) { printf("%d * %f = %f\n", x+1, readnums[x], (x + 1) * readnums[x]); } fclose(buf); } else printf("Cannot open afile.out\n"); } Output: 10.0/1 = 10.000000 10.0/2 = 5.000000 10.0/3 = 3.333333 10.0/4 = 2.500000 10.0/5 = 2.000000 10.0/6 = 1.666667 10.0/7 = 1.428571 10.0/8 = 1.250000 10.0/9 = 1.111111 10.0/10 = 1.000000 Wrote 10 numbers Read 10 numbers 1 * 10.000000 = 10.000000 2 * 5.000000 = 10.000000 3 * 3.333333 = 10.000000 4 * 2.500000 = 10.000000 5 * 2.000000 = 10.000000 6 * 1.666667 = 10.000000 7 * 1.428571 = 10.000000 8 * 1.250000 = 10.000000 9 * 1.111111 = 10.000000 10 * 1.000000 = 10.000000 Explanation: This program uses fwrite to save 10 numbers to a file in binary form. This allows the numbers to be saved in the same pattern of bits as the program is using which provides more accuracy and consistency. Using fprintf would save the numbers as text strings, which could cause the numbers to be truncated. Each number is divided into 10 to produce a variety of numbers. Retrieving the numbers with fread to a new array and multiplying them by the original number shows the numbers were not truncated in the save process. (c) 2008 Microchip Technology Inc. DS51456E-page 69 16-Bit Language Tools Libraries getc Description: Get a character from the stream. Include: <stdio.h> Prototype: int getc(FILE *stream); Argument: stream Return Value: Returns the character read or EOF if a read error occurs or end-of-file is reached. Remarks: getc is the same as the function fgetc. Example: #include <stdio.h> /* for getc, printf, */ /* fopen, fclose, */ /* FILE, NULL, EOF */ pointer to the open stream int main(void) { FILE *buf; char y; if ((buf = fopen("afile.txt", "r")) == NULL) printf("Cannot open afile.txt\n"); else { y = getc(buf); while (y != EOF) { printf("%c|", y); y = getc(buf); } fclose(buf); } } Input: Contents of afile.txt (used as input): Short Longer string Output: S|h|o|r|t| |L|o|n|g|e|r| |s|t|r|i|n|g| | DS51456E-page 70 (c) 2008 Microchip Technology Inc. Standard C Libraries getchar Description: Get a character from stdin. Include: <stdio.h> Prototype: int getchar(void); Return Value: Returns the character read or EOF if a read error occurs or end-of-file is reached. Remarks: Same effect as fgetc with the argument stdin. Example: #include <stdio.h> /* for getchar, printf */ int main(void) { char y; y = getchar(); printf("%c|", y); y = getchar(); printf("%c|", y); y = getchar(); printf("%c|", y); y = getchar(); printf("%c|", y); y = getchar(); printf("%c|", y); } Input: Contents of UartIn.txt (used as stdin input for simulator): Short Longer string Output: S|h|o|r|t| gets Description: Get a string from stdin. Include: <stdio.h> Prototype: char *gets(char *s); Argument: s Return Value: Returns a pointer to the string s if successful; otherwise, returns a null pointer Remarks: The function reads characters from the stream stdin and stores them into the string pointed to by s until it reads a newline character (which is not stored) or sets the end-of-file or error indicators. If any characters were read, a null character is stored immediately after the last read character in the next element of the array. If gets sets the error indicator, the array contents are indeterminate. (c) 2008 Microchip Technology Inc. pointer to the storage string DS51456E-page 71 16-Bit Language Tools Libraries gets (Continued) Example: #include <stdio.h> /* for gets, printf */ int main(void) { char y[50]; gets(y) ; printf("Text: %s\n", y); } Input: Contents of UartIn.txt (used as stdin input for simulator): Short Longer string Output: Text: Short perror Description: Prints an error message to stderr. Include: <stdio.h> Prototype: void perror(const char *s); Argument: s Return Value: None. Remarks: The string s is printed followed by a colon and a space. Then an error message based on errno is printed followed by an newline Example: #include <stdio.h> /* for perror, fopen, */ /* fclose, printf, */ /* FILE, NULL */ string to print int main(void) { FILE *myfile; if ((myfile = fopen("samp.fil", "r+")) == NULL) perror("Cannot open samp.fil"); else printf("Success opening samp.fil\n"); fclose(myfile); } Output: Cannot open samp.fil: DS51456E-page 72 file open error (c) 2008 Microchip Technology Inc. Standard C Libraries printf Description: Prints formatted text to stdout. Include: <stdio.h> Prototype: int printf(const char *format, ...); Arguments: format format control string ... optional arguments Return Value: Returns number of characters generated or a negative number if an error occurs. Remarks: There must be exactly the same number of arguments as there are format specifiers. If the are less arguments than match the format specifiers, the output is undefined. If there are more arguments than match the format specifiers, the remaining arguments are discarded. Each format specifier begins with a percent sign followed by optional fields and a required type as shown here: %[flags][width][.precision][size]type flags 0 + space # left justify the value within a given field width Use 0 for the pad character instead of space (which is the default) generate a plus sign for positive signed values generate a space or signed values that have neither a plus nor a minus sign to prefix 0 on an octal conversion, to prefix 0x or 0X on a hexadecimal conversion, or to generate a decimal point and fraction digits that are otherwise suppressed on a floating-point conversion width specify the number of characters to generate for the conversion. If the asterisk (*) is used instead of a decimal number, the next argument (which must be of type int) will be used for the field width. If the result is less than the field width, pad characters will be used on the left to fill the field. If the result is greater than the field width, the field is expanded to accommodate the value without padding. precision The field width can be followed with dot (.) and a decimal integer representing the precision that specifies one of the following: - minimum number of digits to generate on an integer conversion - number of fraction digits to generate on an e, E, or f conversion - maximum number of significant digits to generate on a g or G conversion - maximum number of characters to generate from a C string on an s conversion If the period appears without the integer the integer is assumed to be zero. If the asterisk (*) is used instead of a decimal number, the next argument (which must be of type int) will be used for the precision. (c) 2008 Microchip Technology Inc. DS51456E-page 73 16-Bit Language Tools Libraries printf (Continued) size h modifier - h modifier - l modifier - l modifier - l modifier - l modifier - ll modifier - ll modifier - L modifier - type d, i o u x X e, E f g, G c s p n % Example: used with type d, i, o, u, x, X; converts the value to a short int or unsigned short int used with n; specifies that the pointer points to a short int used with type d, i, o, u, x, X; converts the value to a long int or unsigned long int used with n; specifies that the pointer points to a long int used with c; specifies a wide character used with type e, E, f, F, g, G; converts the value to a double used with type d, i, o, u, x, X; converts the value to a long long int or unsigned long long int used with n; specifies that the pointer points to a long long int used with e, E, f, g, G; converts the value to a long double signed int unsigned int in octal unsigned int in decimal unsigned int in lowercase hexadecimal unsigned int in uppercase hexadecimal double in scientific notation double decimal notation double (takes the form of e, E or f as appropriate) char - a single character string value of a pointer the associated argument shall be an integer pointer into which is placed the number of characters written so far. No characters are printed. A % character is printed #include <stdio.h> /* for printf */ int main(void) { DS51456E-page 74 /* print a character right justified in a 3 /* character space. printf("%3c\n", 'a'); */ */ /* print an integer, left justified (as /* specified by the minus sign in the format /* string) in a 4 character space. Print a /* second integer that is right justified in /* a 4 character space using the pipe (|) as /* a separator between the integers. printf("%-4d|%4d\n", -4, 4); */ */ */ */ */ */ /* print a number converted to octal in 4 /* digits. printf("%.4o\n", 10); */ */ (c) 2008 Microchip Technology Inc. Standard C Libraries printf (Continued) /* print a number converted to hexadecimal /* format with a 0x prefix. printf("%#x\n", 28); */ */ /* print a float in scientific notation printf("%E\n", 1.1e20); */ /* print a float with 2 fraction digits printf("%.2f\n", -3.346); */ /* print a long float with %E, %e, or %f /* whichever is the shortest version printf("%Lg\n", .02L); */ */ } Output: a -4 | 4 0012 0x1c 1.100000E+20 -3.35 0.02 putc Description: Puts a character to the stream. Include: <stdio.h> Prototype: int putc(int c, FILE *stream); Arguments: c character to be written stream pointer to FILE structure Return Value: Returns the character or EOF if an error occurs or end-of-file is reached. Remarks: putc is the same as the function fputc. Example: #include <stdio.h> /* for putc, EOF, stdout */ int main(void) { char *y; char buf[] = "This is text\n"; int x; x = 0; for (y = buf; (x != EOF) && (*y != '\0'); y++) { x = putc(*y, stdout); putc('|', stdout); } } Output: T|h|i|s| |i|s| |t|e|x|t| | (c) 2008 Microchip Technology Inc. DS51456E-page 75 16-Bit Language Tools Libraries putchar Description: Put a character to stdout. Include: <stdio.h> Prototype: int putchar(int c); Argument: c Return Value: Returns the character or EOF if an error occurs or end-of-file is reached. Remarks: Same effect as fputc with stdout as an argument. Example: #include <stdio.h> /* for putchar, printf, */ /* EOF, stdout */ character to be written int main(void) { char *y; char buf[] = "This is text\n"; int x; x = 0; for (y = buf; (x != EOF) && (*y != '\0'); y++) x = putchar(*y); } Output: This is text puts Description: Put a string to stdout. Include: <stdio.h> Prototype: int puts(const char *s); Argument: s Return Value: Returns a non-negative value if successful; otherwise, returns EOF. Remarks: The function writes characters to the stream stdout. A newline character is appended. The terminating null character is not written to the stream. Example: #include <stdio.h> /* for puts */ string to be written int main(void) { char buf[] = "This is text\n"; puts(buf); puts("|"); } Output: This is text | DS51456E-page 76 (c) 2008 Microchip Technology Inc. Standard C Libraries remove Description: Deletes the specified file. Include: <stdio.h> Prototype: int remove(const char *filename); Argument: filename Return Value: Returns 0 if successful, -1 if not. Remarks: If filename does not exist or is open, remove will fail. Example: #include <stdio.h> /* for remove, printf */ name of file to be deleted. int main(void) { if (remove("myfile.txt") != 0) printf("Cannot remove file"); else printf("File removed"); } Output: File removed rename Description: Renames the specified file. Include: <stdio.h> Prototype: int rename(const char *old, const char *new); Arguments: old pointer to the old name new pointer to the new name. Return Value: Return 0 if successful, non-zero if not. Remarks: The new name must not already exist in the current working directory, the old name must exist in the current working directory. Example: #include <stdio.h> /* for rename, printf */ int main(void) { if (rename("myfile.txt","newfile.txt") != 0) printf("Cannot rename file"); else printf("File renamed"); } Output: File renamed (c) 2008 Microchip Technology Inc. DS51456E-page 77 16-Bit Language Tools Libraries rewind Description: Resets the file pointer to the beginning of the file. Include: <stdio.h> Prototype: void rewind(FILE *stream); Argument: stream Remarks: The function calls fseek(stream, 0L, SEEK_SET) and then clears the error indicator for the given stream. Example: #include <stdio.h> /* /* /* /* stream to reset the file pointer for rewind, fopen, fscanf, fclose, fprintf, printf, FILE, NULL */ */ */ */ int main(void) { FILE *myfile; char s[] = "cookies"; int x = 10; if ((myfile = fopen("afile", "w+")) == NULL) printf("Cannot open afile\n"); else { fprintf(myfile, "%d %s", x, s); printf("I have %d %s.\n", x, s); /* set pointer to beginning of file */ rewind(myfile); fscanf(myfile, "%d %s", &x, &s); printf("I ate %d %s.\n", x, s); fclose(myfile); } } Output: I have 10 cookies. I ate 10 cookies. DS51456E-page 78 (c) 2008 Microchip Technology Inc. Standard C Libraries scanf Description: Scans formatted text from stdin. Include: <stdio.h> Prototype: int scanf(const char *format, ...); Argument: format format control string ... optional arguments Return Value: Returns the number of items successfully converted and assigned. If no items are assigned, a 0 is returned. EOF is returned if an input failure is encountered before the first. Remarks: Each format specifier begins with a percent sign followed by optional fields and a required type as shown here: %[*][width][modifier]type * indicates assignment suppression. This will cause the input field to be skipped and no assignment made. width specify the maximum number of input characters to match for the conversion not including white space that can be skipped. modifier h modifier - h modifier - l modifier - l modifier - l modifier - l modifier - ll modifier - ll modifier - L modifier - (c) 2008 Microchip Technology Inc. used with type d, i, o, u, x, X; converts the value to a short int or unsigned short int. used with n; specifies that the pointer points to a short int used with type d, i, o, u, x, X; converts the value to a long int or unsigned long int used with n; specifies that the pointer points to a long int used with c; specifies a wide character used with type e, E, f, F, g, G; converts the value to a double used with type d, i, o, u, x, X; converts the value to a long long int or unsigned long long int used with n; specifies that the pointer points to a long long int used with e, E, f, g, G; converts the value to a long double DS51456E-page 79 16-Bit Language Tools Libraries scanf (Continued) type d,i o u x X e,E f g,G c s p n [...] % Example: signed int unsigned int in octal unsigned int in decimal unsigned int in lowercase hexadecimal unsigned int in uppercase hexadecimal double in scientific notation double decimal notation double (takes the form of e, E or f as appropriate) char - a single character string value of a pointer the associated argument shall be an integer pointer into, which is placed the number of characters read so far. No characters are scanned. character array. Allows a search of a set of characters. A caret (^) immediately after the left bracket ( [ ) inverts the scanset and allows any ASCII character except those specified between the brackets. A dash character (-) may be used to specify a range beginning with the character before the dash and ending the character after the dash. A null character can not be part of the scanset. A % character is scanned #include <stdio.h> /* for scanf, printf */ int main(void) { int number, items; char letter; char color[30], string[30]; float salary; printf("Enter your favorite number, " "favorite letter, "); printf("favorite color desired salary " "and SSN:\n"); items = scanf("%d %c %[A-Za-z] %f %s", &number, &letter, &color, &salary, &string); printf("Number of items scanned = %d\n", items); printf("Favorite number = %d, ", number); printf("Favorite letter = %c\n", letter); printf("Favorite color = %s, ", color); printf("Desired salary = $%.2f\n", salary); printf("Social Security Number = %s, ", string); } Input: Contents of UartIn.txt (used as stdin input for simulator): 5 T Green 300000 123-45-6789 Output: Enter your favorite number, favorite letter, favorite color, desired salary and SSN: Number of items scanned = 5 Favorite number = 5, Favorite letter = T Favorite color = Green, Desired salary = $300000.00 Social Security Number = 123-45-6789 DS51456E-page 80 (c) 2008 Microchip Technology Inc. Standard C Libraries setbuf Description: Defines how a stream is buffered. Include: <stdio.h> Prototype: void setbuf(FILE *stream, char *buf); Arguments: stream pointer to the open stream buf user allocated buffer Remarks: setbuf must be called after fopen but before any other function calls that operate on the stream. If buf is a null pointer, setbuf calls the function setvbuf(stream, 0, _IONBF, BUFSIZ) for no buffering; otherwise setbuf calls setvbuf(stream, buf, _IOFBF, BUFSIZ) for full buffering with a buffer of size BUFSIZ. See setvbuf. Example: #include <stdio.h> /* for setbuf, printf, */ /* fopen, fclose, */ /* FILE, NULL, BUFSIZ */ int main(void) { FILE *myfile1, *myfile2; char buf[BUFSIZ]; if ((myfile1 = fopen("afile1", "w+")) != NULL) { setbuf(myfile1, NULL); printf("myfile1 has no buffering\n"); fclose(myfile1); } if ((myfile2 = fopen("afile2", "w+")) != NULL) { setbuf(myfile2, buf); printf("myfile2 has full buffering"); fclose(myfile2); } } Output: myfile1 has no buffering myfile2 has full buffering (c) 2008 Microchip Technology Inc. DS51456E-page 81 16-Bit Language Tools Libraries setvbuf Description: Defines the stream to be buffered and the buffer size. Include: <stdio.h> Prototype: int setvbuf(FILE *stream, char *buf, int mode, size_t size); Arguments: stream pointer to the open stream buf user allocated buffer mode type of buffering size size of buffer Return Value: Returns 0 if successful Remarks: setvbuf must be called after fopen but before any other function calls that operate on the stream. For mode use one of the following: _IOFBF - for full buffering _IOLBF - for line buffering _IONBF - for no buffering Example: #include <stdio.h> /* for setvbuf, fopen, */ /* printf, FILE, NULL, */ /* _IONBF, _IOFBF */ int main(void) { FILE *myfile1, *myfile2; char buf[256]; if ((myfile1 = fopen("afile1", "w+")) != NULL) { if (setvbuf(myfile1, NULL, _IONBF, 0) == 0) printf("myfile1 has no buffering\n"); else printf("Unable to define buffer stream " "and/or size\n"); } fclose(myfile1); if ((myfile2 = fopen("afile2", "w+")) != NULL) { if (setvbuf(myfile2, buf, _IOFBF, sizeof(buf)) == 0) printf("myfile2 has a buffer of %d " "characters\n", sizeof(buf)); else printf("Unable to define buffer stream " "and/or size\n"); } fclose(myfile2); } Output: myfile1 has no buffering myfile2 has a buffer of 256 characters DS51456E-page 82 (c) 2008 Microchip Technology Inc. Standard C Libraries sprintf Description: Prints formatted text to a string Include: <stdio.h> Prototype: int sprintf(char *s, const char *format, ...); Arguments: s storage string for output format format control string ... optional arguments Return Value: Returns the number of characters stored in s excluding the terminating null character. Remarks: The format argument has the same syntax and use that it has in printf. Example: #include <stdio.h> /* for sprintf, printf */ int main(void) { char sbuf[100], s[]="Print this string"; int x = 1, y; char a = '\n'; y = sprintf(sbuf, "%s %d time%c", s, x, a); printf("Number of characters printed to " "string buffer = %d\n", y); printf("String = %s\n", sbuf); } Output: Number of characters printed to string buffer = 25 String = Print this string 1 time sscanf Description: Scans formatted text from a string Include: <stdio.h> Prototype: int sscanf(const char *s, const char *format, ...); Arguments: s storage string for input format format control string ... optional arguments Return Value: Returns the number of items successfully converted and assigned. If no items are assigned, a 0 is returned. EOF is returned if an input error is encountered before the first conversion. Remarks: The format argument has the same syntax and use that it has in scanf. (c) 2008 Microchip Technology Inc. DS51456E-page 83 16-Bit Language Tools Libraries sscanf (Continued) Example: #include <stdio.h> /* for sscanf, printf */ int main(void) { char s[] = "5 T green 3000000.00"; int number, items; char letter; char color[10]; float salary; items = sscanf(s, "%d %c %s %f", &number, &letter, &color, &salary); printf("Number of items scanned = %d\n", items); printf("Favorite number = %d\n", number); printf("Favorite letter = %c\n", letter); printf("Favorite color = %s\n", color); printf("Desired salary = $%.2f\n", salary); } Output: Number of items scanned = 4 Favorite number = 5 Favorite letter = T Favorite color = green Desired salary = $3000000.00 tmpfile Description: Creates a temporary file Include: <stdio.h> Prototype: FILE *tmpfile(void) Return Value: Returns a stream pointer if successful; otherwise, returns a NULL pointer. Remarks: tmpfile creates a file with a unique filename. The temporary file is opened in w+b (binary read/write) mode. It will automatically be removed when exit is called; otherwise the file will remain in the directory. Example: #include <stdio.h> /* for tmpfile, printf, */ /* FILE, NULL */ int main(void) { FILE *mytempfile; if ((mytempfile = tmpfile()) == NULL) printf("Cannot create temporary file"); else printf("Temporary file was created"); } Output: Temporary file was created DS51456E-page 84 (c) 2008 Microchip Technology Inc. Standard C Libraries tmpnam Description: Creates a unique temporary filename Include: <stdio.h> Prototype: char *tmpnam(char *s); Argument: s Return Value: Returns a pointer to the filename generated and stores the filename in s. If it can not generate a filename, the NULL pointer is returned. Remarks: The created filename will not conflict with an existing file name. Use L_tmpnam to define the size of array the argument of tmpnam points to. Example: #include <stdio.h> /* for tmpnam, L_tmpnam, */ /* printf, NULL */ pointer to the temporary name int main(void) { char *myfilename; char mybuf[L_tmpnam]; char *myptr = (char *) &mybuf; if ((myfilename = tmpnam(myptr)) == NULL) printf("Cannot create temporary file name"); else printf("Temporary file %s was created", myfilename); } Output: Temporary file ctm00001.tmp was created ungetc Description: Pushes character back onto stream. Include: <stdio.h> Prototype: int ungetc(int c, FILE *stream); Argument: c character to be pushed back stream pointer to the open stream Return Value: Returns the pushed character if successful; otherwise, returns EOF Remarks: The pushed back character will be returned by a subsequent read on the stream. If more than one character is pushed back, they will be returned in the reverse order of their pushing. A successful call to a file positioning function (fseek, fsetpos or rewind) cancels any pushed back characters. Only one character of pushback is guaranteed. Multiple calls to ungetc without an intervening read or file positioning operation may cause a failure. (c) 2008 Microchip Technology Inc. DS51456E-page 85 16-Bit Language Tools Libraries ungetc (Continued) Example: #include <stdio.h> /* for ungetc, fgetc, */ /* printf, fopen, fclose, */ /* FILE, NULL, EOF */ int main(void) { FILE *buf; char y, c; if ((buf = fopen("afile.txt", "r")) == NULL) printf("Cannot open afile.txt\n"); else { y = fgetc(buf); while (y != EOF) { if (y == 'r') { c = ungetc(y, buf); if (c != EOF) { printf("2"); y = fgetc(buf); } } printf("%c", y); y = fgetc(buf); } fclose(buf); } } Input: Contents of afile.txt (used as input): Short Longer string Output: Sho2rt Longe2r st2ring DS51456E-page 86 (c) 2008 Microchip Technology Inc. Standard C Libraries vfprintf Description: Prints formatted data to a stream using a variable length argument list. Include: <stdio.h> <stdarg.h> Prototype: int vfprintf(FILE *stream, const char *format, va_list ap); Arguments: stream pointer to the open stream format format control string ap pointer to a list of arguments Return Value: Returns number of characters generated or a negative number if an error occurs. Remarks: The format argument has the same syntax and use that it has in printf. To access the variable length argument list, the ap variable must be initialized by the macro va_start and may be reinitialized by additional calls to va_arg. This must be done before the vfprintf function is called. Invoke va_end after the function returns. For more details see stdarg.h. Example: #include <stdio.h> /* for vfprintf, fopen, */ /* fclose, printf, */ /* FILE, NULL */ #include <stdarg.h> /* for va_start, /* va_list, va_end */ */ FILE *myfile; void errmsg(const char *fmt, ...) { va_list ap; va_start(ap, fmt); vfprintf(myfile, fmt, ap); va_end(ap); } int main(void) { int num = 3; if ((myfile = fopen("afile.txt", "w")) == NULL) printf("Cannot open afile.txt\n"); else { errmsg("Error: The letter '%c' is not %s\n", 'a', "an integer value."); errmsg("Error: Requires %d%s%c", num, " or more characters.", '\n'); } fclose(myfile); } Output: Contents of afile.txt Error: The letter 'a' is not an integer value. Error: Requires 3 or more characters. (c) 2008 Microchip Technology Inc. DS51456E-page 87 16-Bit Language Tools Libraries vprintf Description: Prints formatted text to stdout using a variable length argument list Include: <stdio.h> <stdarg.h> Prototype: int vprintf(const char *format, va_list ap); Arguments: format format control string ap pointer to a list of arguments Return Value: Returns number of characters generated or a negative number if an error occurs. Remarks: The format argument has the same syntax and use that it has in printf. To access the variable length argument list, the ap variable must be initialized by the macro va_start and may be reinitialized by additional calls to va_arg. This must be done before the vprintf function is called. Invoke va_end after the function returns. For more details see stdarg.h Example: #include <stdio.h> #include <stdarg.h> /* for vprintf, printf */ /* for va_start, */ /* va_list, va_end */ void errmsg(const char *fmt, ...) { va_list ap; va_start(ap, fmt); printf("Error: "); vprintf(fmt, ap); va_end(ap); } int main(void) { int num = 3; errmsg("The letter '%c' is not %s\n", 'a', "an integer value."); errmsg("Requires %d%s\n", num, " or more characters.\n"); } Output: Error: The letter 'a' is not an integer value. Error: Requires 3 or more characters. DS51456E-page 88 (c) 2008 Microchip Technology Inc. Standard C Libraries vsprintf Description: Prints formatted text to a string using a variable length argument list Include: <stdio.h> <stdarg.h> Prototype: int vsprintf(char *s, const char *format, va_list ap); Arguments: s storage string for output format format control string ap pointer to a list of arguments Return Value: Returns number of characters stored in s excluding the terminating null character. Remarks: The format argument has the same syntax and use that it has in printf. To access the variable length argument list, the ap variable must be initialized by the macro va_start and may be reinitialized by additional calls to va_arg. This must be done before the vsprintf function is called. Invoke va_end after the function returns. For more details see stdarg.h Example: #include <stdio.h> #include <stdarg.h> /* for vsprintf, printf */ /* for va_start, */ /* va_list, va_end */ void errmsg(const char *fmt, ...) { va_list ap; char buf[100]; va_start(ap, fmt); vsprintf(buf, fmt, ap); va_end(ap); printf("Error: %s", buf); } int main(void) { int num = 3; errmsg("The letter '%c' is not %s\n", 'a', "an integer value."); errmsg("Requires %d%s\n", num, " or more characters.\n"); } Output: Error: The letter 'a' is not an integer value. Error: Requires 3 or more characters. (c) 2008 Microchip Technology Inc. DS51456E-page 89 16-Bit Language Tools Libraries 2.14 <STDLIB.H> UTILITY FUNCTIONS The header file stdlib.h consists of types, macros and functions that provide text conversions, memory management, searching and sorting abilities, and other general utilities. div_t Description: A type that holds a quotient and remainder of a signed integer division with operands of type int. Include: <stdlib.h> Prototype: typedef struct { int quot, rem; } div_t; Remarks: This is the structure type returned by the function div. ldiv_t Description: A type that holds a quotient and remainder of a signed integer division with operands of type long. Include: <stdlib.h> Prototype: typedef struct { long quot, rem; } ldiv_t; Remarks: This is the structure type returned by the function ldiv. size_t Description: The type of the result of the sizeof operator. Include: <stdlib.h> wchar_t Description: A type that holds a wide character value. Include: <stdlib.h> EXIT_FAILURE Description: Reports unsuccessful termination. Include: <stdlib.h> Remarks: EXIT_FAILURE is a value for the exit function to return an unsuccessful termination status Example: See exit for example of use. EXIT_SUCCESS DS51456E-page 90 Description: Reports successful termination Include: <stdlib.h> Remarks: EXIT_SUCCESS is a value for the exit function to return a successful termination status. Example: See exit for example of use. (c) 2008 Microchip Technology Inc. Standard C Libraries MB_CUR_MAX Description: Maximum number of characters in a multibyte character Include: <stdlib.h> Value: 1 NULL Description: The value of a null pointer constant Include: <stdlib.h> RAND_MAX Description: Maximum value capable of being returned by the rand function Include: <stdlib.h> Value: 32767 abort Description: Aborts the current process. Include: <stdlib.h> Prototype: void abort(void); Remarks: abort will cause the processor to reset. Example: #include <stdio.h> /* for fopen, fclose, */ /* printf, FILE, NULL */ #include <stdlib.h> /* for abort */ int main(void) { FILE *myfile; if ((myfile = fopen("samp.fil", "r")) == NULL) { printf("Cannot open samp.fil\n"); abort(); } else printf("Success opening samp.fil\n"); fclose(myfile); } Output: Cannot open samp.fil ABRT (c) 2008 Microchip Technology Inc. DS51456E-page 91 16-Bit Language Tools Libraries abs Description: Calculates the absolute value. Include: <stdlib.h> Prototype: int abs(int i); Argument: i Return Value: Returns the absolute value of i. Remarks: A negative number is returned as positive; a positive number is unchanged. Example: #include <stdio.h> /* for printf */ #include <stdlib.h> /* for abs */ integer value int main(void) { int i; i = 12; printf("The absolute value of i, abs(i)); %d is i = -2; printf("The absolute value of i, abs(i)); %d is i = 0; printf("The absolute value of i, abs(i)); %d is %d\n", %d\n", %d\n", } Output: The absolute value of The absolute value of The absolute value of 12 is -2 is 0 is 12 2 0 atexit Description: Registers the specified function to be called when the program terminates normally. Include: <stdlib.h> Prototype: int atexit(void(*func)(void)); Argument: func Return Value: Returns a zero if successful; otherwise, returns a non-zero value. Remarks: For the registered functions to be called, the program must terminate with the exit function call. Example: #include <stdio.h> /* for scanf, printf */ #include <stdlib.h> /* for atexit, exit */ function to be called void good_msg(void); void bad_msg(void); void end_msg(void); DS51456E-page 92 (c) 2008 Microchip Technology Inc. Standard C Libraries atexit (Continued) int main(void) { int number; atexit(end_msg); printf("Enter your favorite number:"); scanf("%d", &number); printf(" %d\n", number); if (number == 5) { printf("Good Choice\n"); atexit(good_msg); exit(0); } else { printf("%d!?\n", number); atexit(bad_msg); exit(0); } } void good_msg(void) { printf("That's an excellent number\n"); } void bad_msg(void) { printf("That's an awful number\n"); } void end_msg(void) { printf("Now go count something\n"); } Input: With contents of UartIn.txt (used as stdin input for simulator): 5 Output: Enter your favorite number: 5 Good Choice That's an excellent number Now go count something Input: With contents of UartIn.txt (used as stdin input for simulator): 42 Output: Enter your favorite number: 42 42!? That's an awful number Now go count something (c) 2008 Microchip Technology Inc. DS51456E-page 93 16-Bit Language Tools Libraries atof Description: Converts a string to a double precision floating-point value. Include: <stdlib.h> Prototype: double atof(const char *s); Argument: s Return Value: Returns the converted value if successful; otherwise, returns 0. Remarks: The number may consist of the following: [whitespace] [sign] digits [.digits] [ { e | E }[sign]digits] optional whitespace, followed by an optional sign then a sequence of one or more digits with an optional decimal point, followed by one or more optional digits and an optional e or E followed by an optional signed exponent. The conversion stops when the first unrecognized character is reached. The conversion is the same as strtod(s,0) except it does no error checking so errno will not be set. Example: #include <stdio.h> /* for printf */ #include <stdlib.h> /* for atof */ pointer to the string to be converted int main(void) { char a[] = " 1.28"; char b[] = "27.835e2"; char c[] = "Number1"; double x; x = atof(a); printf("String = \"%s\" float = %f\n", a, x); x = atof(b); printf("String = \"%s\" float = %f\n", b, x); x = atof(c); printf("String = \"%s\" float = %f\n", c, x); } Output: String = "1.28" float = 1.280000 String = "27.835:e2" float = 2783.500000 String = "Number1" float = 0.000000 DS51456E-page 94 (c) 2008 Microchip Technology Inc. Standard C Libraries atoi Description: Converts a string to an integer. Include: <stdlib.h> Prototype: int atoi(const char *s); Argument: s Return Value: Returns the converted integer if successful; otherwise, returns 0. Remarks: The number may consist of the following: [whitespace] [sign] digits optional whitespace, followed by an optional sign then a sequence of one or more digits. The conversion stops when the first unrecognized character is reached. The conversion is equivalent to (int) strtol(s,0,10) except it does no error checking so errno will not be set. Example: #include <stdio.h> /* for printf */ #include <stdlib.h> /* for atoi */ string to be converted int main(void) { char a[] = " -127"; char b[] = "Number1"; int x; x = atoi(a); printf("String = \"%s\"\tint = %d\n", a, x); x = atoi(b); printf("String = \"%s\"\tint = %d\n", b, x); } Output: String = " -127" String = "Number1" int = -127 int = 0 atol Description: Converts a string to a long integer. Include: <stdlib.h> Prototype: long atol(const char *s); Argument: s Return Value: Returns the converted long integer if successful; otherwise, returns 0 Remarks: The number may consist of the following: [whitespace] [sign] digits optional whitespace, followed by an optional sign then a sequence of one or more digits. The conversion stops when the first unrecognized character is reached. The conversion is equivalent to (int) strtol(s,0,10) except it does no error checking so errno will not be set. (c) 2008 Microchip Technology Inc. string to be converted DS51456E-page 95 16-Bit Language Tools Libraries atol (Continued) Example: #include <stdio.h> /* for printf */ #include <stdlib.h> /* for atol */ int main(void) { char a[] = " -123456"; char b[] = "2Number"; long x; x = atol(a); printf("String = \"%s\" int = %ld\n", a, x); x = atol(b); printf("String = \"%s\" int = %ld\n", b, x); } Output: String = " -123456" String = "2Number" int = -123456 int = 2 bsearch DS51456E-page 96 Description: Performs a binary search Include: <stdlib.h> Prototype: void *bsearch(const void *key, const void *base, size_t nelem, size_t size, int (*cmp)(const void *ck, const void *ce)); Arguments: key object to search for base pointer to the start of the search data nelem number of elements size size of elements cmp pointer to the comparison function ck pointer to the key for the search ce pointer to the element being compared with the key. Return Value: Returns a pointer to the object being searched for if found; otherwise, returns NULL. Remarks: The value returned by the compare function is <0 if ck is less than ce, 0 if ck is equal to ce, or >0 if ck is greater than ce. In the following example, qsort is used to sort the list before bsearch is called. bsearch requires the list to be sorted according to the comparison function. This comp uses ascending order. (c) 2008 Microchip Technology Inc. Standard C Libraries bsearch (Continued) Example: #include <stdlib.h> /* for bsearch, qsort */ #include <stdio.h> /* for printf, sizeof */ #define NUM 7 int comp(const void *e1, const void *e2); int main(void) { int list[NUM] = {35, 47, 63, 25, 93, 16, 52}; int x, y; int *r; qsort(list, NUM, sizeof(int), comp); printf("Sorted List: "); for (x = 0; x < NUM; x++) printf("%d ", list[x]); y = 25; r = bsearch(&y, list, NUM, sizeof(int), comp); if (r) printf("\nThe value %d was found\n", y); else printf("\nThe value %d was not found\n", y); y = 75; r = bsearch(&y, list, NUM, sizeof(int), comp); if (r) printf("\nThe value %d was found\n", y); else printf("\nThe value %d was not found\n", y); } int comp(const void *e1, const void *e2) { const int * a1 = e1; const int * a2 = e2; if (*a1 < *a2) return -1; else if (*a1 == *a2) return 0; else return 1; } Output: Sorted List: 16 25 35 The value 25 was found 47 52 63 93 The value 75 was not found (c) 2008 Microchip Technology Inc. DS51456E-page 97 16-Bit Language Tools Libraries calloc Description: Allocates an array in memory and initializes the elements to 0. Include: <stdlib.h> Prototype: void *calloc(size_t nelem, size_t size); Arguments: nelem number of elements size length of each element Return Value: Returns a pointer to the allocated space if successful; otherwise, returns a null pointer. Remarks: Memory returned by calloc is aligned correctly for any size data element and is initialized to zero. Example: /* This program allocates memory for the */ /* array 'i' of long integers and initializes */ /* them to zero. */ #include <stdio.h> /* for printf, NULL */ #include <stdlib.h> /* for calloc, free */ int main(void) { int x; long *i; i = (long *)calloc(5, sizeof(long)); if (i != NULL) { for (x = 0; x < 5; x++) printf("i[%d] = %ld\n", x, i[x]); free(i); } else printf("Cannot allocate memory\n"); } Output: i[0] = i[1] = i[2] = i[3] = i[4] = 0 0 0 0 0 div DS51456E-page 98 Description: Calculates the quotient and remainder of two numbers Include: <stdlib.h> Prototype: div_t div(int numer, int denom); Arguments: numer numerator denom denominator Return Value: Returns the quotient and the remainder. Remarks: The returned quotient will have the same sign as the numerator divided by the denominator. The sign for the remainder will be such that the quotient times the denominator plus the remainder will equal the numerator (quot * denom + rem = numer). Division by zero will invoke the math exception error, which by default, will cause a reset. Write a math error handler to do something else. (c) 2008 Microchip Technology Inc. Standard C Libraries div (Continued) Example: #include <stdlib.h> /* for div, div_t */ #include <stdio.h> /* for printf */ void __attribute__((__interrupt__)) _MathError(void) { printf("Illegal instruction executed\n"); abort(); } int main(void) { int x, y; div_t z; x = 7; y = 3; printf("For div(%d, %d)\n", x, y); z = div(x, y); printf("The quotient is %d and the " "remainder is %d\n\n", z.quot, z.rem); x = 7; y = -3; printf("For div(%d, %d)\n", x, y); z = div(x, y); printf("The quotient is %d and the " "remainder is %d\n\n", z.quot, z.rem); x = -5; y = 3; printf("For div(%d, %d)\n", x, y); z = div(x, y); printf("The quotient is %d and the " "remainder is %d\n\n", z.quot, z.rem); x = 7; y = 7; printf("For div(%d, %d)\n", x, y); z = div(x, y); printf("The quotient is %d and the " "remainder is %d\n\n", z.quot, z.rem); x = 7; y = 0; printf("For div(%d, %d)\n", x, y); z = div(x, y); printf("The quotient is %d and the " "remainder is %d\n\n", z.quot, z.rem); } (c) 2008 Microchip Technology Inc. DS51456E-page 99 16-Bit Language Tools Libraries div (Continued) Output: For div(7, 3) The quotient is 2 and the remainder is 1 For div(7, -3) The quotient is -2 and the remainder is 1 For div(-5, 3) The quotient is -1 and the remainder is -2 For div(7, 7) The quotient is 1 and the remainder is 0 For div(7, 0) Illegal instruction executed ABRT exit Description: Terminates program after clean up. Include: <stdlib.h> Prototype: void exit(int status); Argument: status Remarks: exit calls any functions registered by atexit in reverse order of registration, flushes buffers, closes stream, closes any temporary files created with tmpfile, and resets the processor. This function is customizable. See pic30-libs. Example: #include <stdio.h> exit status /* for fopen, printf, */ /* FILE, NULL */ #include <stdlib.h> /* for exit */ int main(void) { FILE *myfile; if ((myfile = fopen("samp.fil", "r" )) == NULL) { printf("Cannot open samp.fil\n"); exit(EXIT_FAILURE); } else { printf("Success opening samp.fil\n"); exit(EXIT_SUCCESS); } printf("This will not be printed"); } Output: Cannot open samp.fil DS51456E-page 100 (c) 2008 Microchip Technology Inc. Standard C Libraries free Description: Frees memory. Include: <stdlib.h> Prototype: void free(void *ptr); Argument: ptr Remarks: Frees memory previously allocated with calloc, malloc, or realloc. If free is used on space that has already been deallocated (by a previous call to free or by realloc) or on space not allocated with calloc, malloc, or realloc, the behavior is undefined. Example: #include <stdio.h> points to memory to be freed /* for printf, sizeof, */ /* NULL */ #include <stdlib.h> /* for malloc, free */ int main(void) { long *i; if ((i = (long *)malloc(50 * sizeof(long))) == NULL) printf("Cannot allocate memory\n"); else { printf("Memory allocated\n"); free(i); printf("Memory freed\n"); } } Output: Memory allocated Memory freed getenv Description: Get a value for an environment variable. Include: <stdlib.h> Prototype: char *getenv(const char *name); Argument: name Return Value: Returns a pointer to the value of the environment variable if successful; otherwise, returns a null pointer. Remarks: This function must be customized to be used as described (see pic30-libs). By default there are no entries in the environment list for getenv to find. (c) 2008 Microchip Technology Inc. name of environment variable DS51456E-page 101 16-Bit Language Tools Libraries getenv (Continued) Example: #include <stdio.h> /* for printf, NULL */ #include <stdlib.h> /* for getenv */ int main(void) { char *incvar; incvar = getenv("INCLUDE"); if (incvar != NULL) printf("INCLUDE environment variable = %s\n", incvar); else printf("Cannot find environment variable " "INCLUDE "); } Output: Cannot find environment variable INCLUDE labs Description: Calculates the absolute value of a long integer. Include: <stdlib.h> Prototype: long labs(long i); Argument: i Return Value: Returns the absolute value of i. Remarks: A negative number is returned as positive; a positive number is unchanged. Example: #include <stdio.h> /* for printf */ #include <stdlib.h> /* for labs */ long integer value int main(void) { long i; i = 123456; printf("The absolute value of %7ld is %6ld\n", i, labs(i)); i = -246834; printf("The absolute value of %7ld is %6ld\n", i, labs(i)); i = 0; printf("The absolute value of %7ld is %6ld\n", i, labs(i)); } Output: The absolute value of 123456 is 123456 The absolute value of -246834 is 246834 The absolute value of 0 is 0 DS51456E-page 102 (c) 2008 Microchip Technology Inc. Standard C Libraries ldiv Description: Calculates the quotient and remainder of two long integers. Include: <stdlib.h> Prototype: ldiv_t ldiv(long numer, long denom); Arguments: numer numerator denom denominator Return Value: Returns the quotient and the remainder. Remarks: The returned quotient will have the same sign as the numerator divided by the denominator. The sign for the remainder will be such that the quotient times the denominator plus the remainder will equal the numerator (quot * denom + rem = numer). If the denominator is zero, the behavior is undefined. Example: #include <stdlib.h> /* for ldiv, ldiv_t */ #include <stdio.h> /* for printf */ int main(void) { long x,y; ldiv_t z; x = 7; y = 3; printf("For ldiv(%ld, %ld)\n", x, y); z = ldiv(x, y); printf("The quotient is %ld and the " "remainder is %ld\n\n", z.quot, z.rem); x = 7; y = -3; printf("For ldiv(%ld, %ld)\n", x, y); z = ldiv(x, y); printf("The quotient is %ld and the " "remainder is %ld\n\n", z.quot, z.rem); x = -5; y = 3; printf("For ldiv(%ld, %ld)\n", x, y); z = ldiv(x, y); printf("The quotient is %ld and the " "remainder is %ld\n\n", z.quot, z.rem); x = 7; y = 7; printf("For ldiv(%ld, %ld)\n", x, y); z = ldiv(x, y); printf("The quotient is %ld and the " "remainder is %ld\n\n", z.quot, z.rem); x = 7; y = 0; printf("For ldiv(%ld, %ld)\n", x, y); z = ldiv(x, y); printf("The quotient is %ld and the " "remainder is %ld\n\n", z.quot, z.rem); } (c) 2008 Microchip Technology Inc. DS51456E-page 103 16-Bit Language Tools Libraries ldiv (Continued) Output: For ldiv(7, 3) The quotient is 2 and the remainder is 1 For ldiv(7, -3) The quotient is -2 and the remainder is 1 For ldiv(-5, 3) The quotient is -1 and the remainder is -2 For ldiv(7, 7) The quotient is 1 and the remainder is 0 For ldiv(7, 0) The quotient is -1 and the remainder is 7 Explanation: In the last example (ldiv(7,0)) the denominator is zero, the behavior is undefined. malloc Description: Allocates memory. Include: <stdlib.h> Prototype: void *malloc(size_t size); Argument: size Return Value: Returns a pointer to the allocated space if successful; otherwise, returns a null pointer. Remarks: malloc does not initialize memory it returns. Example: #include <stdio.h> number of characters to allocate /* for printf, sizeof, */ /* NULL */ #include <stdlib.h> /* for malloc, free */ int main(void) { long *i; if ((i = (long *)malloc(50 * sizeof(long))) == NULL) printf("Cannot allocate memory\n"); else { printf("Memory allocated\n"); free(i); printf("Memory freed\n"); } } Output: Memory allocated Memory freed DS51456E-page 104 (c) 2008 Microchip Technology Inc. Standard C Libraries mblen Description: Gets the length of a multibyte character. (See Remarks.) Include: <stdlib.h> Prototype: int mblen(const char *s, size_t n); Arguments: s points to the multibyte character n number of bytes to check Return Value: Returns zero if s points to a null character; otherwise, returns 1. Remarks: The 16-bit compiler does not support multibyte characters with length greater than 1 byte. mbstowcs Description: Converts a multibyte string to a wide character string. (See Remarks.) Include: <stdlib.h> Prototype: size_t mbstowcs(wchar_t *wcs, const char *s, size_t n); Arguments: wcs points to the wide character string s points to the multibyte string n the number of wide characters to convert. Return Value: Returns the number of wide characters stored excluding the null character. Remarks: mbstowcs converts n number of wide characters unless it encounters a null wide character first. The 16-bit compiler does not support multibyte characters with length greater than 1 byte. mbtowc Description: Converts a multibyte character to a wide character. (See Remarks.) Include: <stdlib.h> Prototype: int mbtowc(wchar_t *pwc, const char *s, size_t n); Arguments: pwc points to the wide character s points to the multibyte character n number of bytes to check Return Value: Returns zero if s points to a null character; otherwise, returns 1 Remarks: The resulting wide character will be stored at pwc. The 16-bit compiler does not support multibyte characters with length greater than 1 byte. (c) 2008 Microchip Technology Inc. DS51456E-page 105 16-Bit Language Tools Libraries qsort Description: Performs a quick sort. Include: <stdlib.h> Prototype: void qsort(void *base, size_t nelem, size_t size, int (*cmp)(const void *e1, const void *e2)); Arguments: base pointer to the start of the array nelem number of elements size size of the elements cmp pointer to the comparison function e1 pointer to the key for the search e2 pointer to the element being compared with the key Remarks: qsort overwrites the array with the sorted array. The comparison function is supplied by the user. In the following example, the list is sorted according to the comparison function. This comp uses ascending order. Example: #include <stdlib.h> /* for qsort */ #include <stdio.h> /* for printf */ #define NUM 7 int comp(const void *e1, const void *e2); int main(void) { int list[NUM] = {35, 47, 63, 25, 93, 16, 52}; int x; printf("Unsorted List: "); for (x = 0; x < NUM; x++) printf("%d ", list[x]); qsort(list, NUM, sizeof(int), comp); printf("\n"); printf("Sorted List: "); for (x = 0; x < NUM; x++) printf("%d ", list[x]); } int comp(const void *e1, const void *e2) { const int * a1 = e1; const int * a2 = e2; if (*a1 < *a2) return -1; else if (*a1 == *a2) return 0; else return 1; } Output: Unsorted List: 35 Sorted List: 16 DS51456E-page 106 47 25 63 35 25 47 93 52 16 63 52 93 (c) 2008 Microchip Technology Inc. Standard C Libraries rand Description: Generates a pseudo-random integer. Include: <stdlib.h> Prototype: int rand(void); Return Value: Returns an integer between 0 and RAND_MAX. Remarks: Calls to this function return pseudo-random integer values in the range [0,RAND_MAX]. To use this function effectively, you must seed the random number generator using the srand function. This function will always return the same sequence of integers when no seeds are used (as in the example below) or when identical seed values are used. (See srand for seed example.) Example: #include <stdio.h> /* for printf */ #include <stdlib.h> /* for rand */ int main(void) { int x; for (x = 0; x < 5; x++) printf("Number = %d\n", rand()); } Output: Number Number Number Number Number = = = = = 21422 2061 16443 11617 9125 Notice if the program is run a second time, the numbers are the same. See the example for srand to seed the random number generator. realloc Description: Reallocates memory to allow a size change. Include: <stdlib.h> Prototype: void *realloc(void *ptr, size_t size); Arguments: ptr points to previously allocated memory size new size to allocate to Return Value: Returns a pointer to the allocated space if successful; otherwise, returns a null pointer. Remarks: If the existing object is smaller than the new object, the entire existing object is copied to the new object and the remainder of the new object is indeterminate. If the existing object is larger than the new object, the function copies as much of the existing object as will fit in the new object. If realloc succeeds in allocating a new object, the existing object will be deallocated; otherwise, the existing object is left unchanged. Keep a temporary pointer to the existing object since realloc will return a null pointer on failure. (c) 2008 Microchip Technology Inc. DS51456E-page 107 16-Bit Language Tools Libraries realloc (Continued) Example: #include <stdio.h> /* for printf, sizeof, NULL */ #include <stdlib.h> /* for realloc, malloc, free */ int main(void) { long *i, *j; if ((i = (long *)malloc(50 * sizeof(long))) == NULL) printf("Cannot allocate memory\n"); else { printf("Memory allocated\n"); /* Temp pointer in case realloc() fails */ j = i; if ((i = (long *)realloc(i, 25 * sizeof(long))) == NULL) { printf("Cannot reallocate memory\n"); /* j pointed to allocated memory */ free(j); } else { printf("Memory reallocated\n"); free(i); } } } Output: Memory allocated Memory reallocated DS51456E-page 108 (c) 2008 Microchip Technology Inc. Standard C Libraries srand Description: Set the starting seed for the pseudo-random number sequence. Include: <stdlib.h> Prototype: void srand(unsigned int seed); Argument: seed Return Value: None Remarks: This function sets the starting seed for the pseudo-random number sequence generated by the rand function. The rand function will always return the same sequence of integers when identical seed values are used. If rand is called with a seed value of 1, the sequence of numbers generated will be the same as if rand had been called without srand having been called first. Example: #include <stdio.h> /* for printf */ #include <stdlib.h> /* for rand, srand */ starting value for the pseudo-random number sequence int main(void) { int x; srand(7); for (x = 0; x < 5; x++) printf("Number = %d\n", rand()); } Output: Number Number Number Number Number = = = = = 16327 5931 23117 30985 29612 strtod Description: Converts a partial string to a floating-point number of type double. Include: <stdlib.h> Prototype: double strtod(const char *s, char **endptr); Arguments: s string to be converted endptr pointer to the character at which the conversion stopped Return Value: Returns the converted number if successful; otherwise, returns 0. Remarks: The number may consist of the following: [whitespace] [sign] digits [.digits] [ { e | E }[sign]digits] optional whitespace, followed by an optional sign, then a sequence of one or more digits with an optional decimal point, followed by one or more optional digits and an optional e or E followed by an optional signed exponent. strtod converts the string until it reaches a character that cannot be converted to a number. endptr will point to the remainder of the string starting with the first unconverted character. If a range error occurs, errno will be set. (c) 2008 Microchip Technology Inc. DS51456E-page 109 16-Bit Language Tools Libraries strtod (Continued) Example: #include <stdio.h> /* for printf */ #include <stdlib.h> /* for strtod */ int main(void) { char *end; char a[] = "1.28 inches"; char b[] = "27.835e2i"; char c[] = "Number1"; double x; x = strtod(a, &end); printf("String = \"%s\" float = %f\n", a, x ); printf("Stopped at: %s\n\n", end ); x = strtod(b, &end); printf("String = \"%s\" float = %f\n", b, x ); printf("Stopped at: %s\n\n", end ); x = strtod(c, &end); printf("String = \"%s\" float = %f\n", c, x ); printf("Stopped at: %s\n\n", end ); } Output: String = "1.28 inches" Stopped at: inches float = 1.280000 String = "27.835e2i" float = 2783.500000 Stopped at: i String = "Number1" Stopped at: Number1 DS51456E-page 110 float = 0.000000 (c) 2008 Microchip Technology Inc. Standard C Libraries strtol Description: Converts a partial string to a long integer. Include: <stdlib.h> Prototype: long strtol(const char *s, char **endptr, int base); Arguments: s string to be converted endptr pointer to the character at which the conversion stopped base number base to use in conversion Return Value: Returns the converted number if successful; otherwise, returns 0. Remarks: If base is zero, strtol attempts to determine the base automatically. It can be octal, determined by a leading zero, hexadecimal, determined by a leading 0x or 0X, or decimal in any other case. If base is specified strtol converts a sequence of digits and letters a-z (case insensitive), where a-z represents the numbers 10-36. Conversion stops when an out of base number is encountered. endptr will point to the remainder of the string starting with the first unconverted character. If a range error occurs, errno will be set. Example: #include <stdio.h> /* for printf */ #include <stdlib.h> /* for strtol */ int main(void) { char *end; char a[] = "-12BGEE"; char b[] = "1234Number"; long x; x = strtol(a, &end, 16); printf("String = \"%s\" long = %ld\n", a, x ); printf("Stopped at: %s\n\n", end ); x = strtol(b, &end, 4); printf("String = \"%s\" long = %ld\n", b, x ); printf("Stopped at: %s\n\n", end ); } Output: String = "-12BGEE" Stopped at: GEE long = -299 String = "1234Number" Stopped at: 4Number (c) 2008 Microchip Technology Inc. long = 27 DS51456E-page 111 16-Bit Language Tools Libraries strtoul Description: Converts a partial string to an unsigned long integer. Include: <stdlib.h> Prototype: unsigned long strtoul(const char *s, char **endptr, int base); Arguments: s string to be converted endptr pointer to the character at which the conversion stopped base number base to use in conversion Return Value: Returns the converted number if successful; otherwise, returns 0. Remarks: If base is zero, strtol attempts to determine the base automatically. It can be octal, determined by a leading zero, hexadecimal, determined by a leading 0x or 0X, or decimal in any other case. If base is specified strtol converts a sequence of digits and letters a-z (case insensitive), where a-z represents the numbers 10-36. Conversion stops when an out of base number is encountered. endptr will point to the remainder of the string starting with the first unconverted character. If a range error occurs, errno will be set. Example: #include <stdio.h> /* for printf */ #include <stdlib.h> /* for strtoul */ int main(void) { char *end; char a[] = "12BGET3"; char b[] = "0x1234Number"; char c[] = "-123abc"; unsigned long x; x = strtoul(a, &end, 25); printf("String = \"%s\" long = %lu\n", a, x ); printf("Stopped at: %s\n\n", end ); x = strtoul(b, &end, 0); printf("String = \"%s\" long = %lu\n", b, x ); printf("Stopped at: %s\n\n", end ); x = strtoul(c, &end, 0); printf("String = \"%s\" long = %lu\n", c, x ); printf("Stopped at: %s\n\n", end ); } Output: String = "12BGET3" Stopped at: T3 long = 429164 String = "0x1234Number" Stopped at: Number String = "-123abc" Stopped at: abc DS51456E-page 112 long = 4660 long = 4294967173 (c) 2008 Microchip Technology Inc. Standard C Libraries system Description: Execute a command. Include: <stdlib.h> Prototype: int system(const char *s); Argument: s Remarks: This function must be customized to be used as described (see pic30-libs). By default system will cause a reset if called with anything other than NULL. system(NULL) will do nothing. Example: /* This program uses system */ /* to TYPE its source file. */ command to be executed #include <stdlib.h> /* for system */ int main(void) { system("type sampsystem.c"); } Output: System(type sampsystem.c) called: Aborting wctomb Description: Converts a wide character to a multibyte character. (See Remarks.) Include: <stdlib.h> Prototype: int wctomb(char *s, wchar_t wchar); Arguments: s points to the multibyte character wchar the wide character to be converted Return Value: Returns zero if s points to a null character; otherwise, returns 1. Remarks: The resulting multibyte character is stored at s. The 16-bit compiler does not support multibyte characters with length greater than 1 character. wcstombs Description: Converts a wide character string to a multibyte string. (See Remarks.) Include: <stdlib.h> Prototype: size_t wcstombs(char *s, const wchar_t *wcs, size_t n); Arguments: s points to the multibyte string wcs points to the wide character string n the number of characters to convert Return Value: Returns the number of characters stored excluding the null character. Remarks: wcstombs converts n number of multibyte characters unless it encounters a null character first. The 16-bit compiler does not support multibyte characters with length greater than 1 character. (c) 2008 Microchip Technology Inc. DS51456E-page 113 16-Bit Language Tools Libraries 2.15 <STRING.H> STRING FUNCTIONS The header file string.h consists of types, macros and functions that provide tools to manipulate strings. size_t Description: The type of the result of the sizeof operator. Include: <string.h> NULL Description: The value of a null pointer constant. Include: <string.h> memchr Description: Locates a character in a buffer. Include: <string.h> Prototype: void *memchr(const void *s, int c, size_t n); Arguments: s pointer to the buffer c character to search for n number of characters to check Return Value: Returns a pointer to the location of the match if successful; otherwise, returns null. Remarks: memchr stops when it finds the first occurrence of c or after searching n number of characters. Example: #include <string.h> /* for memchr, NULL */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = "What time is it?"; char ch1 = 'i', ch2 = 'y'; char *ptr; int res; printf("buf1 : %s\n\n", buf1); ptr = memchr(buf1, ch1, 50); if (ptr != NULL) { res = ptr - buf1 + 1; printf("%c found at position %d\n", ch1, res); } else printf("%c not found\n", ch1); DS51456E-page 114 (c) 2008 Microchip Technology Inc. Standard C Libraries memchr (Continued) printf("\n"); ptr = memchr(buf1, ch2, 50); if (ptr != NULL) { res = ptr - buf1 + 1; printf("%c found at position %d\n", ch2, res); } else printf("%c not found\n", ch2); } Output: buf1 : What time is it? i found at position 7 y not found memcmp Description: Compare the contents of two buffers. Include: <string.h> Prototype: int memcmp(const void *s1, const void *s2, size_t n); Arguments: s1 first buffer s2 second buffer n number of characters to compare Return Value: Returns a positive number if s1 is greater than s2, zero if s1 is equal to s2, or a negative number if s1 is less than s2. Remarks: This function compares the first n characters in s1 to the first n characters in s2 and returns a value indicating whether the buffers are less than, equal to or greater than each other. Example: #include <string.h> /* memcmp */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = "Where is the time?"; char buf2[50] = "Where did they go?"; char buf3[50] = "Why?"; int res; printf("buf1 : %s\n", buf1); printf("buf2 : %s\n", buf2); printf("buf3 : %s\n\n", buf3); res = memcmp(buf1, buf2, 6); if (res < 0) printf("buf1 comes before buf2\n"); else if (res == 0) printf("6 characters of buf1 and buf2 " "are equal\n"); else printf("buf2 comes before buf1\n"); (c) 2008 Microchip Technology Inc. DS51456E-page 115 16-Bit Language Tools Libraries memcmp (Continued) printf("\n"); res = memcmp(buf1, buf2, 20); if (res < 0) printf("buf1 comes before buf2\n"); else if (res == 0) printf("20 characters of buf1 and buf2 " "are equal\n"); else printf("buf2 comes before buf1\n"); printf("\n"); res = memcmp(buf1, buf3, 20); if (res < 0) printf("buf1 comes before buf3\n"); else if (res == 0) printf("20 characters of buf1 and buf3 " "are equal\n"); else printf("buf3 comes before buf1\n"); } Output: buf1 : Where is the time? buf2 : Where did they go? buf3 : Why? 6 characters of buf1 and buf2 are equal buf2 comes before buf1 buf1 comes before buf3 DS51456E-page 116 (c) 2008 Microchip Technology Inc. Standard C Libraries memcpy Description: Copies characters from one buffer to another. Include: <string.h> Prototype: void *memcpy(void *dst , const void *src , size_t n); Arguments: dst buffer to copy characters to src buffer to copy characters from n number of characters to copy Return Value: Returns dst. Remarks: memcpy copies n characters from the source buffer src to the destination buffer dst. If the buffers overlap, the behavior is undefined. Example: #include <string.h> /* memcpy */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = ""; char buf2[50] = "Where is the time?"; char buf3[50] = "Why?"; printf("buf1 : %s\n", buf1); printf("buf2 : %s\n", buf2); printf("buf3 : %s\n\n", buf3); memcpy(buf1, buf2, 6); printf("buf1 after memcpy of 6 chars of " "buf2: \n\t%s\n", buf1); printf("\n"); memcpy(buf1, buf3, 5); printf("buf1 after memcpy of 5 chars of " "buf3: \n\t%s\n", buf1); } Output: buf1 : buf2 : Where is the time? buf3 : Why? buf1 after memcpy of 6 chars of buf2: Where buf1 after memcpy of 5 chars of buf3: Why? (c) 2008 Microchip Technology Inc. DS51456E-page 117 16-Bit Language Tools Libraries memmove Description: Copies n characters of the source buffer into the destination buffer, even if the regions overlap. Include: <string.h> Prototype: void *memmove(void *s1, const void *s2, size_t n); Arguments: s1 buffer to copy characters to (destination) s2 buffer to copy characters from (source) n number of characters to copy from s2 to s1 Return Value: Returns a pointer to the destination buffer Remarks: If the buffers overlap, the effect is as if the characters are read first from s2 then written to s1 so the buffer is not corrupted. Example: #include <string.h> /* for memmove */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = "When time marches on"; char buf2[50] = "Where is the time?"; char buf3[50] = "Why?"; printf("buf1 : %s\n", buf1); printf("buf2 : %s\n", buf2); printf("buf3 : %s\n\n", buf3); memmove(buf1, buf2, 6); printf("buf1 after memmove of 6 chars of " "buf2: \n\t%s\n", buf1); printf("\n"); memmove(buf1, buf3, 5); printf("buf1 after memmove of 5 chars of " "buf3: \n\t%s\n", buf1); } Output: buf1 : When time marches on buf2 : Where is the time? buf3 : Why? buf1 after memmove of 6 chars of buf2: Where ime marches on buf1 after memmove of 5 chars of buf3: Why? DS51456E-page 118 (c) 2008 Microchip Technology Inc. Standard C Libraries memset Description: Copies the specified character into the destination buffer. Include: <string.h> Prototype: void *memset(void *s, int c, size_t n); Arguments: s buffer c character to put in buffer n number of times Return Value: Returns the buffer with characters written to it. Remarks: The character c is written to the buffer n times. Example: #include <string.h> /* for memset */ #include <stdio.h> /* for printf */ int main(void) { char buf1[20] = "What time is it?"; char buf2[20] = ""; char ch1 = '?', ch2 = 'y'; char *ptr; int res; printf("memset(\"%s\", \'%c\',4);\n", buf1, ch1); memset(buf1, ch1, 4); printf("buf1 after memset: %s\n", buf1); printf("\n"); printf("memset(\"%s\", \'%c\',10);\n", buf2, ch2); memset(buf2, ch2, 10); printf("buf2 after memset: %s\n", buf2); } Output: memset("What time is it?", '?',4); buf1 after memset: ???? time is it? memset("", 'y',10); buf2 after memset: yyyyyyyyyy (c) 2008 Microchip Technology Inc. DS51456E-page 119 16-Bit Language Tools Libraries strcat Description: Appends a copy of the source string to the end of the destination string. Include: <string.h> Prototype: char *strcat(char *s1, const char *s2); Arguments: s1 null terminated destination string to copy to s2 null terminated source string to be copied Return Value: Returns a pointer to the destination string. Remarks: This function appends the source string (including the terminating null character) to the end of the destination string. The initial character of the source string overwrites the null character at the end of the destination string. If the buffers overlap, the behavior is undefined. Example: #include <string.h> /* for strcat, strlen */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = "We're here"; char buf2[50] = "Where is the time?"; printf("buf1 : %s\n", buf1); printf("\t(%d characters)\n\n", strlen(buf1)); printf("buf2 : %s\n", buf2); printf("\t(%d characters)\n\n", strlen(buf2)); strcat(buf1, buf2); printf("buf1 after strcat of buf2: \n\t%s\n", buf1); printf("\t(%d characters)\n", strlen(buf1)); printf("\n"); strcat(buf1, "Why?"); printf("buf1 after strcat of \"Why?\": \n\t%s\n", buf1); printf("\t(%d characters)\n", strlen(buf1)); } Output: buf1 : We're here (10 characters) buf2 : Where is the time? (18 characters) buf1 after strcat of buf2: We're hereWhere is the time? (28 characters) buf1 after strcat of "Why?": We're hereWhere is the time?Why? (32 characters) DS51456E-page 120 (c) 2008 Microchip Technology Inc. Standard C Libraries strchr Description: Locates the first occurrence of a specified character in a string. Include: <string.h> Prototype: char *strchr(const char *s, int c); Arguments: s pointer to the string c character to search for Return Value: Returns a pointer to the location of the match if successful; otherwise, returns a null pointer. Remarks: This function searches the string s to find the first occurrence of the character c. Example: #include <string.h> /* for strchr, NULL */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = "What time is it?"; char ch1 = 'm', ch2 = 'y'; char *ptr; int res; printf("buf1 : %s\n\n", buf1); ptr = strchr(buf1, ch1); if (ptr != NULL) { res = ptr - buf1 + 1; printf("%c found at position %d\n", ch1, res); } else printf("%c not found\n", ch1); printf("\n"); ptr = strchr(buf1, ch2); if (ptr != NULL) { res = ptr - buf1 + 1; printf("%c found at position %d\n", ch2, res); } else printf("%c not found\n", ch2); } Output: buf1 : What time is it? m found at position 8 y not found (c) 2008 Microchip Technology Inc. DS51456E-page 121 16-Bit Language Tools Libraries strcmp Description: Compares two strings. Include: <string.h> Prototype: int strcmp(const char *s1, const char *s2); Arguments: s1 first string s2 second string Return Value: Returns a positive number if s1 is greater than s2, zero if s1 is equal to s2, or a negative number if s1 is less than s2. Remarks: This function compares successive characters from s1 and s2 until they are not equal or the null terminator is reached. Example: #include <string.h> /* for strcmp */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = "Where is the time?"; char buf2[50] = "Where did they go?"; char buf3[50] = "Why?"; int res; printf("buf1 : %s\n", buf1); printf("buf2 : %s\n", buf2); printf("buf3 : %s\n\n", buf3); res = strcmp(buf1, buf2); if (res < 0) printf("buf1 comes before buf2\n"); else if (res == 0) printf("buf1 and buf2 are equal\n"); else printf("buf2 comes before buf1\n"); printf("\n"); res = strcmp(buf1, buf3); if (res < 0) printf("buf1 comes before buf3\n"); else if (res == 0) printf("buf1 and buf3 are equal\n"); else printf("buf3 comes before buf1\n"); printf("\n"); res = strcmp("Why?", buf3); if (res < 0) printf("\"Why?\" comes before buf3\n"); else if (res == 0) printf("\"Why?\" and buf3 are equal\n"); else printf("buf3 comes before \"Why?\"\n"); } DS51456E-page 122 (c) 2008 Microchip Technology Inc. Standard C Libraries strcmp (Continued) Output: buf1 : Where is the time? buf2 : Where did they go? buf3 : Why? buf2 comes before buf1 buf1 comes before buf3 "Why?" and buf3 are equal strcoll Description: Compares one string to another. (See Remarks.) Include: <string.h> Prototype: int strcoll(const char *s1, const char *s2); Arguments: s1 first string s2 second string Return Value: Using the locale-dependent rules, it returns a positive number if s1 is greater than s2, zero if s1 is equal to s2, or a negative number if s1 is less than s2. Remarks: Since the 16-bit compiler does not support alternate locales, this function is equivalent to strcmp. strcpy Description: Copy the source string into the destination string. Include: <string.h> Prototype: char *strcpy(char *s1, const char *s2); Arguments: s1 destination string to copy to s2 source string to copy from Return Value: Returns a pointer to the destination string. Remarks: All characters of s2 are copied, including the null terminating character. If the strings overlap, the behavior is undefined. Example: #include <string.h> /* for strcpy, strlen */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = "We're here"; char buf2[50] = "Where is the time?"; char buf3[50] = "Why?"; printf("buf1 : %s\n", buf1); printf("buf2 : %s\n", buf2); printf("buf3 : %s\n\n", buf3); strcpy(buf1, buf2); printf("buf1 after strcpy of buf2: \n\t%s\n\n", buf1); (c) 2008 Microchip Technology Inc. DS51456E-page 123 16-Bit Language Tools Libraries strcpy (Continued) strcpy(buf1, buf3); printf("buf1 after strcpy of buf3: \n\t%s\n", buf1); } Output: buf1 : We're here buf2 : Where is the time? buf3 : Why? buf1 after strcpy of buf2: Where is the time? buf1 after strcpy of buf3: Why? strcspn Description: Calculate the number of consecutive characters at the beginning of a string that are not contained in a set of characters. Include: <string.h> Prototype: size_t strcspn(const char *s1, const char *s2); Arguments: s1 pointer to the string to be searched s2 pointer to characters to search for Return Value: Returns the length of the segment in s1 not containing characters found in s2. Remarks: This function will determine the number of consecutive characters from the beginning of s1 that are not contained in s2. Example: #include <string.h> /* for strcspn */ #include <stdio.h> /* for printf */ int main(void) { char str1[20] char str2[20] char str3[20] char str4[20] int res; = = = = "hello"; "aeiou"; "animal"; "xyz"; res = strcspn(str1, str2); printf("strcspn(\"%s\", \"%s\") = %d\n", str1, str2, res); res = strcspn(str3, str2); printf("strcspn(\"%s\", \"%s\") = %d\n", str3, str2, res); res = strcspn(str3, str4); printf("strcspn(\"%s\", \"%s\") = %d\n", str3, str4, res); } Output: strcspn("hello", "aeiou") = 1 strcspn("animal", "aeiou") = 0 strcspn("animal", "xyz") = 6 DS51456E-page 124 (c) 2008 Microchip Technology Inc. Standard C Libraries strcspn (Continued) Explanation: In the first result, e is in s2 so it stops counting after h. In the second result, a is in s2. In the third result, none of the characters of s1 are in s2 so all characters are counted. strerror Description: Gets an internal error message. Include: <string.h> Prototype: char *strerror(int errcode); Argument: errcode Return Value: Returns a pointer to an internal error message string corresponding to the specified error code errcode. Remarks: The array pointed to by strerror may be overwritten by a subsequent call to this function. Example: #include <stdio.h> number of the error code /* /* #include <string.h> /* #include <errno.h> /* for fopen, fclose, printf, FILE, NULL for strerror for errno */ */ */ */ int main(void) { FILE *myfile; if ((myfile = fopen("samp.fil", "r+")) == NULL) printf("Cannot open samp.fil: %s\n", strerror(errno)); else printf("Success opening samp.fil\n"); fclose(myfile); } Output: Cannot open samp.fil: file open error strlen Description: Finds the length of a string. Include: <string.h> Prototype: size_t strlen(const char *s); Argument: s Return Value: Returns the length of a string. Remarks: This function determines the length of the string, not including the terminating null character. (c) 2008 Microchip Technology Inc. the string DS51456E-page 125 16-Bit Language Tools Libraries strlen (Continued) Example: #include <string.h> /* for strlen */ #include <stdio.h> /* for printf */ int main(void) { char str1[20] = "We are here"; char str2[20] = ""; char str3[20] = "Why me?"; printf("str1 : %s\n", str1); printf("\t(string length = %d characters)\n\n", strlen(str1)); printf("str2 : %s\n", str2); printf("\t(string length = %d characters)\n\n", strlen(str2)); printf("str3 : %s\n", str3); printf("\t(string length = %d characters)\n\n\n", strlen(str3)); } Output: str1 : We are here (string length = 11 characters) str2 : (string length = 0 characters) str3 : Why me? (string length = 7 characters) strncat Description: Append a specified number of characters from the source string to the destination string. Include: <string.h> Prototype: char *strncat(char *s1, const char *s2, size_t n); Arguments: s1 destination string to copy to s2 source string to copy from n number of characters to append Return Value: Returns a pointer to the destination string. Remarks: This function appends up to n characters (a null character and characters that follow it are not appended) from the source string to the end of the destination string. If a null character is not encountered, then a terminating null character is appended to the result. If the strings overlap, the behavior is undefined. Example: #include <string.h> /* for strncat, strlen */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = "We're here"; char buf2[50] = "Where is the time?"; char buf3[50] = "Why?"; DS51456E-page 126 (c) 2008 Microchip Technology Inc. Standard C Libraries strncat (Continued) printf("buf1 : %s\n", buf1); printf("\t(%d characters)\n\n", strlen(buf1)); printf("buf2 : %s\n", buf2); printf("\t(%d characters)\n\n", strlen(buf2)); printf("buf3 : %s\n", buf3); printf("\t(%d characters)\n\n\n", strlen(buf3)); strncat(buf1, buf2, 6); printf("buf1 after strncat of 6 characters " "of buf2: \n\t%s\n", buf1); printf("\t(%d characters)\n", strlen(buf1)); printf("\n"); strncat(buf1, buf2, 25); printf("buf1 after strncat of 25 characters " "of buf2: \n\t%s\n", buf1); printf("\t(%d characters)\n", strlen(buf1)); printf("\n"); strncat(buf1, buf3, 4); printf("buf1 after strncat of 4 characters " "of buf3: \n\t%s\n", buf1); printf("\t(%d characters)\n", strlen(buf1)); } Output: buf1 : We're here (10 characters) buf2 : Where is the time? (18 characters) buf3 : Why? (4 characters) buf1 after strncat of 6 characters of buf2: We're hereWhere (16 characters) buf1 after strncat of 25 characters of buf2: We're hereWhere Where is the time? (34 characters) buf1 after strncat of 4 characters of buf3: We're hereWhere Where is the time?Why? (38 characters) (c) 2008 Microchip Technology Inc. DS51456E-page 127 16-Bit Language Tools Libraries strncmp Description: Compare two strings, up to a specified number of characters. Include: <string.h> Prototype: int strncmp(const char *s1, const char *s2, size_t n); Arguments: s1 first string s2 second string n number of characters to compare Return Value: Returns a positive number if s1 is greater than s2, zero if s1 is equal to s2, or a negative number if s1 is less than s2. Remarks: strncmp returns a value based on the first character that differs between s1 and s2. Characters that follow a null character are not compared. Example: #include <string.h> /* for strncmp */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = "Where is the time?"; char buf2[50] = "Where did they go?"; char buf3[50] = "Why?"; int res; printf("buf1 : %s\n", buf1); printf("buf2 : %s\n", buf2); printf("buf3 : %s\n\n", buf3); res = strncmp(buf1, buf2, 6); if (res < 0) printf("buf1 comes before buf2\n"); else if (res == 0) printf("6 characters of buf1 and buf2 " "are equal\n"); else printf("buf2 comes before buf1\n"); printf("\n"); res = strncmp(buf1, buf2, 20); if (res < 0) printf("buf1 comes before buf2\n"); else if (res == 0) printf("20 characters of buf1 and buf2 " "are equal\n"); else printf("buf2 comes before buf1\n"); DS51456E-page 128 (c) 2008 Microchip Technology Inc. Standard C Libraries strncmp (Continued) printf("\n"); res = strncmp(buf1, buf3, 20); if (res < 0) printf("buf1 comes before buf3\n"); else if (res == 0) printf("20 characters of buf1 and buf3 " "are equal\n"); else printf("buf3 comes before buf1\n"); } Output: buf1 : Where is the time? buf2 : Where did they go? buf3 : Why? 6 characters of buf1 and buf2 are equal buf2 comes before buf1 buf1 comes before buf3 strncpy Description: Copy characters from the source string into the destination string, up to the specified number of characters. Include: <string.h> Prototype: char *strncpy(char *s1, const char *s2, size_t n); Arguments: s1 destination string to copy to s2 source string to copy from n number of characters to copy Return Value: Returns a pointer to the destination string. Remarks: Copies n characters from the source string to the destination string. If the source string is less than n characters, the destination is filled with null characters to total n characters. If n characters were copied and no null character was found then the destination string will not be null-terminated. If the strings overlap, the behavior is undefined. Example: #include <string.h> /* for strncpy, strlen */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] char buf2[50] char buf3[50] char buf4[7] printf("buf1 printf("buf2 printf("buf3 printf("buf4 (c) 2008 Microchip Technology Inc. = = = = : : : : "We're here"; "Where is the time?"; "Why?"; "Where?"; %s\n", %s\n", %s\n", %s\n", buf1); buf2); buf3); buf4); DS51456E-page 129 16-Bit Language Tools Libraries strncpy (Continued) strncpy(buf1, buf2, 6); printf("buf1 after strncpy of 6 characters " "of buf2: \n\t%s\n", buf1); printf("\t( %d characters)\n", strlen(buf1)); printf("\n"); strncpy(buf1, buf2, 18); printf("buf1 after strncpy of 18 characters " "of buf2: \n\t%s\n", buf1); printf("\t( %d characters)\n", strlen(buf1)); printf("\n"); strncpy(buf1, buf3, 5); printf("buf1 after strncpy of 5 characters " "of buf3: \n\t%s\n", buf1); printf("\t( %d characters)\n", strlen(buf1)); printf("\n"); strncpy(buf1, buf4, 9); printf("buf1 after strncpy of 9 characters " "of buf4: \n\t%s\n", buf1); printf("\t( %d characters)\n", strlen(buf1)); } Output: buf1 : We're here buf2 : Where is the time? buf3 : Why? buf4 : Where? buf1 after strncpy of 6 characters of buf2: Where here ( 10 characters) buf1 after strncpy of 18 characters of buf2: Where is the time? ( 18 characters) buf1 after strncpy of 5 characters of buf3: Why? ( 4 characters) buf1 after strncpy of 9 characters of buf4: Where? ( 6 characters) DS51456E-page 130 (c) 2008 Microchip Technology Inc. Standard C Libraries strncpy (Continued) Explanation: Each buffer contains the string shown, followed by null characters for a length of 50. Using strlen will find the length of the string up to but not including the first null character. In the first example, 6 characters of buf2 ("Where ") replace the first 6 characters of buf1 ("We're ") and the rest of buf1 remains the same ("here" plus null characters). In the second example, 18 characters replace the first 18 characters of buf1 and the rest remain null characters. In the third example, 5 characters of buf3 ("Why?" plus a null terminating character) replace the first 5 characters of buf1. buf1 now actually contains ("Why?", 1 null character, " is the time?", 32 null characters). strlen shows 4 characters because it stops when it reaches the first null character. In the fourth example, since buf4 is only 7 characters strncpy uses 2 additional null characters to replace the first 9 characters of buf1. The result of buf1 is 6 characters ("Where?") followed by 3 null characters, followed by 9 characters ("the time?"), followed by 32 null characters. strpbrk Description: Search a string for the first occurrence of a character from a specified set of characters. Include: <string.h> Prototype: char *strpbrk(const char *s1, const char *s2); Arguments: s1 pointer to the string to be searched s2 pointer to characters to search for Return Value: Returns a pointer to the matched character in s1 if found; otherwise, returns a null pointer. Remarks: This function will search s1 for the first occurrence of a character contained in s2. Example: #include <string.h> /* for strpbrk, NULL */ #include <stdio.h> /* for printf */ int main(void) { char str1[20] = "What time is it?"; char str2[20] = "xyz"; char str3[20] = "eou?"; char *ptr; int res; printf("strpbrk(\"%s\", \"%s\")\n", str1, str2); ptr = strpbrk(str1, str2); if (ptr != NULL) { res = ptr - str1 + 1; printf("match found at position %d\n", res); } else printf("match not found\n"); (c) 2008 Microchip Technology Inc. DS51456E-page 131 16-Bit Language Tools Libraries strpbrk (Continued) printf("\n"); printf("strpbrk(\"%s\", \"%s\")\n", str1, str3); ptr = strpbrk(str1, str3); if (ptr != NULL) { res = ptr - str1 + 1; printf("match found at position %d\n", res); } else printf("match not found\n"); } Output: strpbrk("What time is it?", "xyz") match not found strpbrk("What time is it?", "eou?") match found at position 9 strrchr Description: Search for the last occurrence of a specified character in a string. Include: <string.h> Prototype: char *strrchr(const char *s, int c); Arguments: s pointer to the string to be searched c character to search for Return Value: Returns a pointer to the character if found; otherwise, returns a null pointer. Remarks: The function searches the string s, including the terminating null character, to find the last occurrence of character c. Example: #include <string.h> /* for strrchr, NULL */ #include <stdio.h> /* for printf */ int main(void) { char buf1[50] = "What time is it?"; char ch1 = 'm', ch2 = 'y'; char *ptr; int res; printf("buf1 : %s\n\n", buf1); ptr = strrchr(buf1, ch1); if (ptr != NULL) { res = ptr - buf1 + 1; printf("%c found at position %d\n", ch1, res); } else printf("%c not found\n", ch1); DS51456E-page 132 (c) 2008 Microchip Technology Inc. Standard C Libraries strrchr (Continued) printf("\n"); ptr = strrchr(buf1, ch2); if (ptr != NULL) { res = ptr - buf1 + 1; printf("%c found at position %d\n", ch2, res); } else printf("%c not found\n", ch2); } Output: buf1 : What time is it? m found at position 8 y not found strspn Description: Calculate the number of consecutive characters at the beginning of a string that are contained in a set of characters. Include: <string.h> Prototype: size_t strspn(const char *s1, const char *s2); Arguments: s1 pointer to the string to be searched s2 pointer to characters to search for Return Value: Returns the number of consecutive characters from the beginning of s1 that are contained in s2. Remarks: This function stops searching when a character from s1 is not in s2. Example: #include <string.h> /* for strspn */ #include <stdio.h> /* for printf */ int main(void) { char str1[20] char str2[20] char str3[20] char str4[20] int res; = = = = "animal"; "aeiounm"; "aimnl"; "xyz"; res = strspn(str1, str2); printf("strspn(\"%s\", \"%s\") = %d\n", str1, str2, res); res = strspn(str1, str3); printf("strspn(\"%s\", \"%s\") = %d\n", str1, str3, res); res = strspn(str1, str4); printf("strspn(\"%s\", \"%s\") = %d\n", str1, str4, res); } (c) 2008 Microchip Technology Inc. DS51456E-page 133 16-Bit Language Tools Libraries strspn (Continued) Output: strspn("animal", "aeiounm") = 5 strspn("animal", "aimnl") = 6 strspn("animal", "xyz") = 0 Explanation: In the first result, l is not in s2. In the second result, the terminating null is not in s2. In the third result, a is not in s2 , so the comparison stops. strstr Description: Search for the first occurrence of a string inside another string. Include: <string.h> Prototype: char *strstr(const char *s1, const char *s2); Arguments: s1 pointer to the string to be searched s2 pointer to substring to be searched for Return Value: Returns the address of the first element that matches the substring if found; otherwise, returns a null pointer. Remarks: This function will find the first occurrence of the string s2 (excluding the null terminator) within the string s1. If s2 points to a zero length string, s1 is returned. Example: #include <string.h> /* for strstr, NULL */ #include <stdio.h> /* for printf */ int main(void) { char str1[20] = "What time is it?"; char str2[20] = "is"; char str3[20] = "xyz"; char *ptr; int res; printf("str1 : %s\n", str1); printf("str2 : %s\n", str2); printf("str3 : %s\n\n", str3); ptr = strstr(str1, str2); if (ptr != NULL) { res = ptr - str1 + 1; printf("\"%s\" found at position %d\n", str2, res); } else printf("\"%s\" not found\n", str2); DS51456E-page 134 (c) 2008 Microchip Technology Inc. Standard C Libraries strstr (Continued) printf("\n"); ptr = strstr(str1, str3); if (ptr != NULL) { res = ptr - str1 + 1; printf("\"%s\" found at position %d\n", str3, res); } else printf("\"%s\" not found\n", str3); } Output: str1 : What time is it? str2 : is str3 : xyz "is" found at position 11 "xyz" not found strtok Description: Break a string into substrings, or tokens, by inserting null characters in place of specified delimiters. Include: <string.h> Prototype: char *strtok(char *s1, const char *s2); Arguments: s1 pointer to the null terminated string to be searched s2 iters) pointer to characters to be searched for (used as delim- Return Value: Returns a pointer to the first character of a token (the first character in s1 that does not appear in the set of characters of s2). If no token is found, the null pointer is returned. Remarks: A sequence of calls to this function can be used to split up a string into substrings (or tokens) by replacing specified characters with null characters. The first time this function is invoked on a particular string, that string should be passed in s1. After the first time, this function can continue parsing the string from the last delimiter by invoking it with a null value passed in s1. It skips all leading characters that appear in the string s2 (delimiters), then skips all characters not appearing in s2 (this segment of characters is the token), and then overwrites the next character with a null character, terminating the current token. The function strtok then saves a pointer to the character that follows, from which the next search will start. If strtok finds the end of the string before it finds a delimiter, the current token extends to the end of the string pointed to by s1. If this is the first call to strtok, it does not modify the string (no null characters are written to s1). The set of characters that is passed in s2 need not be the same for each call to strtok. If strtok is called with a non-null parameter for s1 after the initial call, the string becomes the new string to search. The old string previously searched will be lost. (c) 2008 Microchip Technology Inc. DS51456E-page 135 16-Bit Language Tools Libraries strtok (Continued) Example: #include <string.h> /* for strtok, NULL */ #include <stdio.h> / * for printf */ int main(void) { char str1[30] = "Here, on top of the world!"; char delim[5] = ", ."; char *word; int x; printf("str1 : %s\n", str1); x = 1; word = strtok(str1,delim); while (word != NULL) { printf("word %d: %s\n", x++, word); word = strtok(NULL, delim); } } Output: str1 : Here, on top of the world! word 1: Here word 2: on word 3: top word 4: of word 5: the word 6: world! strxfrm DS51456E-page 136 Description: Transforms a string using the locale-dependent rules. (See Remarks.) Include: <string.h> Prototype: size_t strxfrm(char *s1, const char *s2, size_t n); Arguments: s1 destination string s2 source string to be transformed n number of characters to transform Return Value: Returns the length of the transformed string not including the terminating null character. If n is zero, the string is not transformed (s1 may be a point null in this case) and the length of s2 is returned. Remarks: If the return value is greater than or equal to n, the content of s1 is indeterminate. Since the 16-bit compiler does not support alternate locales, the transformation is equivalent to strcpy, except that the length of the destination string is bounded by n-1. (c) 2008 Microchip Technology Inc. Standard C Libraries 2.16 <TIME.H> DATE AND TIME FUNCTIONS The header file time.h consists of types, macros and functions that manipulate time. clock_t Description: Stores processor time values. Include: <time.h> Prototype: typedef long clock_t size_t Description: The type of the result of the sizeof operator. Include: <time.h> struct tm Description: Structure used to hold the time and date (calendar time). Include: <time.h> Prototype: struct tm { int tm_sec;/*seconds after the minute ( 0 to 61 )*/ /*allows for up to two leap seconds*/ int tm_min;/*minutes after the hour ( 0 to 59 )*/ int tm_hour;/*hours since midnight ( 0 to 23 )*/ int tm_mday;/*day of month ( 1 to 31 )*/ int tm_mon;/*month ( 0 to 11 where January = 0 )*/ int tm_year;/*years since 1900*/ int tm_wday;/*day of week ( 0 to 6 where Sunday = 0 )*/ int tm_yday;/*day of year ( 0 to 365 where January 1 = 0 )*/ int tm_isdst;/*Daylight Savings Time flag*/ } Remarks: If tm_isdst is a positive value, Daylight Savings is in effect. If it is zero, Daylight Saving time is not in effect. If it is a negative value, the status of Daylight Saving Time is not known. time_t Description: Represents calendar time values. Include: <time.h> Prototype: typedef long time_t CLOCKS_PER_SEC Description: Number of processor clocks per second. Include: <time.h> Prototype: #define CLOCKS_PER_SEC Value: 1 Remarks: The compiler returns clock ticks (instruction cycles) not actual time. (c) 2008 Microchip Technology Inc. DS51456E-page 137 16-Bit Language Tools Libraries NULL Description: The value of a null pointer constant. Include: <time.h> asctime Description: Converts the time structure to a character string. Include: <time.h> Prototype: char *asctime(const struct tm *tptr); Argument: tptr Return Value: Returns a pointer to a character string of the following format: DDD MMM dd hh:mm:ss YYYY DDD is day of the week MMM is month of the year dd is day of the month hh is hour mm is minute ss is second YYYY is year Example: #include <time.h> /* for asctime, tm */ #include <stdio.h> /* for printf */ time/date structure volatile int i; int main(void) { struct tm when; time_t whattime; when.tm_sec = 30; when.tm_min = 30; when.tm_hour = 2; when.tm_mday = 1; when.tm_mon = 1; when.tm_year = 103; whattime = mktime(&when); printf("Day and time is %s\n", asctime(&when)); } Output: Day and time is Sat Feb 1 02:30:30 2003 clock DS51456E-page 138 Description: Calculates the processor time. Include: <time.h> Prototype: clock_t clock(void); Return Value: Returns the number of clock ticks of elapsed processor time. Remarks: If the target environment cannot measure elapsed processor time, the function returns -1, cast as a clock_t. (i.e. (clock_t) -1) By default, The 16-bit compiler returns the time as instruction cycles. (c) 2008 Microchip Technology Inc. Standard C Libraries clock (Continued) Example: #include <time.h> /* for clock */ #include <stdio.h> /* for printf */ volatile int i; int main(void) { clock_t start, stop; int ct; start = clock(); for (i = 0; i < 10; i++) stop = clock(); printf("start = %ld\n", start); printf("stop = %ld\n", stop); } Output: start = 0 stop = 317 ctime Description: Converts calendar time to a string representation of local time. Include: <time.h> Prototype: char *ctime(const time_t *tod); Argument: tod Return Value: Returns the address of a string that represents the local time of the parameter passed. Remarks: This function is equivalent to asctime(localtime(tod)). Example: #include <time.h> /* for mktime, tm, ctime */ #include <stdio.h> /* for printf */ pointer to stored time int main(void) { time_t whattime; struct tm nowtime; nowtime.tm_sec = 30; nowtime.tm_min = 30; nowtime.tm_hour = 2; nowtime.tm_mday = 1; nowtime.tm_mon = 1; nowtime.tm_year = 103; whattime = mktime(&nowtime); printf("Day and time %s\n", ctime(&whattime)); } Output: Day and time Sat Feb (c) 2008 Microchip Technology Inc. 1 02:30:30 2003 DS51456E-page 139 16-Bit Language Tools Libraries difftime Description: Find the difference between two times. Include: <time.h> Prototype: double difftime(time_t t1, time_t t0); Arguments: t1 ending time t0 beginning time Return Value: Returns the number of seconds between t1 and t0. Remarks: By default, the 16-bit compiler returns the time as instruction cycles so difftime returns the number of ticks between t1 and t0. Example: #include <time.h> /* for clock, difftime */ #include <stdio.h> /* for printf */ volatile int i; int main(void) { clock_t start, stop; double elapsed; start = clock(); for (i = 0; i < 10; i++) stop = clock(); printf("start = %ld\n", start); printf("stop = %ld\n", stop); elapsed = difftime(stop, start); printf("Elapsed time = %.0f\n", elapsed); } Output: start = 0 stop = 317 Elapsed time = 317 gmtime DS51456E-page 140 Description: Converts calendar time to time structure expressed as Universal Time Coordinated (UTC) also known as Greenwich Mean Time (GMT). Include: <time.h> Prototype: struct tm *gmtime(const time_t *tod); Argument: tod Return Value: Returns the address of the time structure. Remarks: This function breaks down the tod value into the time structure of type tm. By default, the 16-bit compiler returns the time as instruction cycles. With this default gmtime and localtime will be equivalent except gmtime will return tm_isdst (Daylight Savings Time flag) as zero to indicate that Daylight Savings Time is not in effect. pointer to stored time (c) 2008 Microchip Technology Inc. Standard C Libraries gmtime (Continued) Example: #include <time.h> /* for gmtime, asctime, */ /* time_t, tm */ #include <stdio.h> /* for printf */ int main(void) { time_t timer; struct tm *newtime; timer = 1066668182; /* Mon Oct 20 16:43:02 2003 */ newtime = gmtime(&timer); printf("UTC time = %s\n", asctime(newtime)); } Output: UTC time = Mon Oct 20 16:43:02 2003 localtime Description: Converts a value to the local time. Include: <time.h> Prototype: struct tm *localtime(const time_t *tod); Argument: tod Return Value: Returns the address of the time structure. Remarks: By default, the 16-bit compiler returns the time as instruction cycles. With this default localtime and gmtime will be equivalent except localtime will return tm_isdst (Daylight Savings Time flag) as -1 to indicate that the status of Daylight Savings Time is not known. Example: #include <time.h> pointer to stored time /* for localtime, */ /* asctime, time_t, tm */ #include <stdio.h> /* for printf */ int main(void) { time_t timer; struct tm *newtime; timer = 1066668182; /* Mon Oct 20 16:43:02 2003 */ newtime = localtime(&timer); printf("Local time = %s\n", asctime(newtime)); } Output: Local time = Mon Oct 20 16:43:02 2003 (c) 2008 Microchip Technology Inc. DS51456E-page 141 16-Bit Language Tools Libraries mktime Description: Converts local time to a calendar value. Include: <time.h> Prototype: time_t mktime(struct tm *tptr); Argument: tptr Return Value: Returns the calendar time encoded as a value of time_t. Remarks: If the calendar time cannot be represented, the function returns -1, cast as a time_t (i.e. (time_t) -1). Example: #include <time.h> a pointer to the time structure /* /* /* #include <stdio.h> /* for localtime, asctime, mktime, time_t, tm for printf */ */ */ */ int main(void) { time_t timer, whattime; struct tm *newtime; timer = 1066668182; /* Mon Oct 20 16:43:02 2003 */ /* localtime allocates space for struct tm */ newtime = localtime(&timer); printf("Local time = %s", asctime(newtime)); whattime = mktime(newtime); printf("Calendar time as time_t = %ld\n", whattime); } Output: Local time = Mon Oct 20 16:43:02 2003 Calendar time as time_t = 1066668182 strftime Description: Formats the time structure to a string based on the format parameter. Include: <time.h> Prototype: size_t strftime(char *s, size_t n, const char *format, const struct tm *tptr); Arguments: s output string n maximum length of string format format-control string tptr pointer to tm data structure Return Value: Returns the number of characters placed in the array s if the total including the terminating null is not greater than n. Otherwise, the function returns 0 and the contents of array s are indeterminate. Remarks: The format parameters follow: %a abbreviated weekday name %A full weekday name %b abbreviated month name %B full month name %c appropriate date and time representation %d day of the month (01-31) %H hour of the day (00-23) DS51456E-page 142 (c) 2008 Microchip Technology Inc. Standard C Libraries strftime (Continued) %I hour of the day (01-12) %j day of the year (001-366) %m month of the year (01-12) %M minute of the hour (00-59) %p AM/PM designator %S second of the minute (00-61) allowing for up to two leap seconds %U week number of the year where Sunday is the first day of week 1 (00-53) %w weekday where Sunday is day 0 (0-6) %W week number of the year where Monday is the first day of week 1 (00-53) %x appropriate date representation %X appropriate time representation %y year without century (00-99) %Y year with century %Z time zone (possibly abbreviated) or no characters if time zone is unavailable %% percent character % Example: #include <time.h> /* /* /* #include <stdio.h> /* for strftime, localtime, time_t, tm for printf */ */ */ */ int main(void) { time_t timer, whattime; struct tm *newtime; char buf[128]; timer = 1066668182; /* Mon Oct 20 16:43:02 2003 */ /* localtime allocates space for structure */ newtime = localtime(&timer); strftime(buf, 128, "It was a %A, %d days into the " "month of %B in the year %Y.\n", newtime); printf(buf); strftime(buf, 128, "It was %W weeks into the year " "or %j days into the year.\n", newtime); printf(buf); } Output: It was a Monday, 20 days into the month of October in the year 2003. It was 42 weeks into the year or 293 days into the year. (c) 2008 Microchip Technology Inc. DS51456E-page 143 16-Bit Language Tools Libraries time Description: Calculates the current calendar time. Include: <time.h> Prototype: time_t time(time_t *tod); Argument: tod Return Value: Returns the calendar time encoded as a value of time_t. Remarks: If the target environment cannot determine the time, the function returns -1, cast as a time_t. By default, the 16-bit compiler returns the time as instruction cycles. This function is customizable. See pic30-libs. Example: #include <time.h> /* for time */ #include <stdio.h> /* for printf */ pointer to storage location for time volatile int i; int main(void) { time_t ticks; time(0); /* start time */ for (i = 0; i < 10; i++) /* waste time */ time(&ticks); /* get time */ printf("Time = %ld\n", ticks); } Output: Time = 256 DS51456E-page 144 (c) 2008 Microchip Technology Inc. 16-BIT LANGUAGE TOOLS LIBRARIES Chapter 3. Standard C Libraries - Math Functions 3.1 INTRODUCTION Standard ANSI C library math functions are contained in the file libm-omf.a, where omf will be coff or elf depending upon the selected object module format. 3.1.1 Assembly Code Applications A free version of the math functions library and header file is available from the Microchip web site. No source code is available with this free version. 3.1.2 C Code Applications The MPLAB C Compiler for PIC24 MCUs and dsPIC(R) DSCs (formerly MPLAB C30) install directory (c:\Program Files\Microchip\MPLAB C30) contains the following subdirectories with library-related files: * lib - standard C library files * src\libm - source code for math library functions, batch file to rebuild the library * support\h - header files for libraries In addition, there is a file, ResourceGraphs.pdf, which contains diagrams of resources used by each function, located in lib. 3.1.3 Chapter Organization This chapter is organized as follows: * Using the Standard C Libraries * <math.h> mathematical functions 3.2 USING THE STANDARD C LIBRARIES Building an application which utilizes the standard C libraries requires two types of files: header files and library files. 3.2.1 Header Files All standard C library entities are declared or defined in one or more standard headers (See list in Section 3.1.3 "Chapter Organization".) To make use of a library entity in a program, write an include directive that names the relevant standard header. The contents of a standard header is included by naming it in an include directive, as in: #include <stdio.h> /* include I/O facilities */ The standard headers can be included in any order. Do not include a standard header within a declaration. Do not define macros that have the same names as keywords before including a standard header. A standard header never includes another standard header. (c) 2008 Microchip Technology Inc. DS51456E-page 145 16-Bit Language Tools Libraries 3.2.2 Library Files The archived library files contain all the individual object files for each library function. When linking an application, the library file must be provided as an input to the linker (using the --library or -l linker option) such that the functions used by the application may be linked into the application. A typical C application will require three library files: libc-omf.a, libm-omf.a, and libpic30-omf.a. (See Section 1.2 "OMF-Specific Libraries/Start-up Modules" for more on OMF-specific libraries.) These libraries will be included automatically if linking is performed using the compiler. Note: DS51456E-page 146 Some standard library functions require a heap. These include the standard I/O functions that open files and the memory allocation functions. See the "MPLAB(R) Assembler, Linker and Utilities for PIC24 MCUs and dsPIC(R) DSCs User's Guide" (DS51317) and "MPLAB(R) C Compiler for PIC24 MCUs and dsPIC(R) DSCs User's Guide" (DS51284) for more information on the heap. (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions 3.3 <MATH.H> MATHEMATICAL FUNCTIONS The header file math.h consists of a macro and various functions that calculate common mathematical operations. Error conditions may be handled with a domain error or range error (see errno.h). A domain error occurs when the input argument is outside the domain over which the function is defined. The error is reported by storing the value of EDOM in errno and returning a particular value defined for each function. A range error occurs when the result is too large or too small to be represented in the target precision. The error is reported by storing the value of ERANGE in errno and returning HUGE_VAL if the result overflowed (return value was too large) or a zero if the result underflowed (return value is too small). Responses to special values, such as NaNs, zeros, and infinities, may vary depending upon the function. Each function description includes a definition of the function's response to such values. HUGE_VAL Description: HUGE_VAL is returned by a function on a range error (e.g., the function tries to return a value too large to be represented in the target precision). Include: <math.h> Remarks: -HUGE_VAL is returned if a function result is negative and is too large (in magnitude) to be represented in the target precision. When the printed result is +/- HUGE_VAL, it will be represented by +/- inf. acos Description: Calculates the trigonometric arc cosine function of a double precision floating-point value. Include: <math.h> Prototype: double acos (double x); Argument: x Return Value: Returns the arc cosine in radians in the range of 0 to pi (inclusive). Remarks: A domain error occurs if x is less than -1 or greater than 1. Example: #include <math.h> /* for acos */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value between -1 and 1 for which to return the arc cosine int main(void) { double x,y; errno = 0; x = -2.0; y = acos (x); if (errno) perror("Error"); printf("The arccosine of %f is %f\n\n", x, y); (c) 2008 Microchip Technology Inc. DS51456E-page 147 16-Bit Language Tools Libraries acos (Continued) errno = 0; x = 0.10; y = acos (x); if (errno) perror("Error"); printf("The arccosine of %f is %f\n\n", x, y); } Output: Error: domain error The arccosine of -2.000000 is nan The arccosine of 0.100000 is 1.470629 acosf Description: Calculates the trigonometric arc cosine function of a single precision floating-point value. Include: <math.h> Prototype: float acosf (float x); Argument: x Return Value: Returns the arc cosine in radians in the range of 0 to pi (inclusive). Remarks: A domain error occurs if x is less than -1 or greater than 1. Example: #include <math.h> /* for acosf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value between -1 and 1 int main(void) { float x, y; errno = 0; x = 2.0F; y = acosf (x); if (errno) perror("Error"); printf("The arccosine of %f is %f\n\n", x, y); errno = 0; x = 0.0F; y = acosf (x); if (errno) perror("Error"); printf("The arccosine of %f is %f\n", x, y); } Output: Error: domain error The arccosine of 2.000000 is nan The arccosine of 0.000000 is 1.570796 DS51456E-page 148 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions asin Description: Calculates the trigonometric arc sine function of a double precision floating-point value. Include: <math.h> Prototype: double asin (double x); Argument: x Return Value: Returns the arc sine in radians in the range of -pi/2 to +pi/2 (inclusive). Remarks: A domain error occurs if x is less than -1 or greater than 1. Example: #include <math.h> /* for asin */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value between -1 and 1 for which to return the arc sine int main(void) { double x, y; errno = 0; x = 2.0; y = asin (x); if (errno) perror("Error"); printf("The arcsine of %f is %f\n\n", x, y); errno = 0; x = 0.0; y = asin (x); if (errno) perror("Error"); printf("The arcsine of %f is %f\n\n", x, y); } Output: Error: domain error The arcsine of 2.000000 is nan The arcsine of 0.000000 is 0.000000 asinf Description: Calculates the trigonometric arc sine function of a single precision floating-point value. Include: <math.h> Prototype: float asinf (float x); Argument: x Return Value: Returns the arc sine in radians in the range of -pi/2 to +pi/2 (inclusive). Remarks: A domain error occurs if x is less than -1 or greater than 1. Example: #include <math.h> /* for asinf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value between -1 and 1 int main(void) { float x, y; (c) 2008 Microchip Technology Inc. DS51456E-page 149 16-Bit Language Tools Libraries asinf (Continued) errno = 0; x = 2.0F; y = asinf(x); if (errno) perror("Error"); printf("The arcsine of %f is %f\n\n", x, y); errno = 0; x = 0.0F; y = asinf(x); if (errno) perror("Error"); printf("The arcsine of %f is %f\n\n", x, y); } Output: Error: domain error The arcsine of 2.000000 is nan The arcsine of 0.000000 is 0.000000 atan Description: Calculates the trigonometric arc tangent function of a double precision floating-point value. Include: <math.h> Prototype: double atan (double x); Argument: x Return Value: Returns the arc tangent in radians in the range of -pi/2 to +pi/2 (inclusive). Remarks: No domain or range error will occur. Example: #include <math.h> /* for atan */ #include <stdio.h> /* for printf */ value for which to return the arc tangent int main(void) { double x, y; x = 2.0; y = atan (x); printf("The arctangent of %f is %f\n\n", x, y); x = -1.0; y = atan (x); printf("The arctangent of %f is %f\n\n", x, y); } Output: The arctangent of 2.000000 is 1.107149 The arctangent of -1.000000 is -0.785398 DS51456E-page 150 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions atanf Description: Calculates the trigonometric arc tangent function of a single precision floating-point value. Include: <math.h> Prototype: float atanf (float x); Argument: x Return Value: Returns the arc tangent in radians in the range of -pi/2 to +pi/2 (inclusive). Remarks: No domain or range error will occur. Example: #include <math.h> /* for atanf */ #include <stdio.h> /* for printf */ value for which to return the arc tangent int main(void) { float x, y; x = 2.0F; y = atanf (x); printf("The arctangent of %f is %f\n\n", x, y); x = -1.0F; y = atanf (x); printf("The arctangent of %f is %f\n\n", x, y); } Output: The arctangent of 2.000000 is 1.107149 The arctangent of -1.000000 is -0.785398 atan2 Description: Calculates the trigonometric arc tangent function of y/x. Include: <math.h> Prototype: double atan2 (double y, double x); Arguments: y y value for which to return the arc tangent x x value for which to return the arc tangent Return Value: Returns the arc tangent in radians in the range of -pi to pi (inclusive) with the quadrant determined by the signs of both parameters. Remarks: A domain error occurs if both x and y are zero or both x and y are +/- infinity. Example: #include <math.h> /* for atan2 */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ int main(void) { double x, y, z; (c) 2008 Microchip Technology Inc. DS51456E-page 151 16-Bit Language Tools Libraries atan2 (Continued) errno = 0; x = 0.0; y = 2.0; z = atan2(y, x); if (errno) perror("Error"); printf("The arctangent of %f/%f is %f\n\n", y, x, z); errno = 0; x = -1.0; y = 0.0; z = atan2(y, x); if (errno) perror("Error"); printf("The arctangent of %f/%f is %f\n\n", y, x, z); errno = 0; x = 0.0; y = 0.0; z = atan2(y, x); if (errno) perror("Error"); printf("The arctangent of %f/%f is %f\n\n", y, x, z); } Output: The arctangent of 2.000000/0.000000 is 1.570796 The arctangent of 0.000000/-1.000000 is 3.141593 Error: domain error The arctangent of 0.000000/0.000000 is nan DS51456E-page 152 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions atan2f Description: Calculates the trigonometric arc tangent function of y/x. Include: <math.h> Prototype: float atan2f (float y, float x); Arguments: y y value for which to return the arc tangent x x value for which to return the arc tangent Return Value: Returns the arc tangent in radians in the range of -pi to pi with the quadrant determined by the signs of both parameters. Remarks: A domain error occurs if both x and y are zero or both x and y are +/- infinity. Example: #include <math.h> /* for atan2f */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ int main(void) { float x, y, z; errno = 0; x = 2.0F; y = 0.0F; z = atan2f (y, x); if (errno) perror("Error"); printf("The arctangent of %f/%f is %f\n\n", y, x, z); errno = 0; x = 0.0F; y = -1.0F; z = atan2f (y, x); if (errno) perror("Error"); printf("The arctangent of %f/%f is %f\n\n", y, x, z); errno = 0; x = 0.0F; y = 0.0F; z = atan2f (y, x); if (errno) perror("Error"); printf("The arctangent of %f/%f is %f\n\n", y, x, z); } Output: The arctangent of 2.000000/0.000000 is 1.570796 The arctangent of 0.000000/-1.000000 is 3.141593 Error: domain error The arctangent of 0.000000/0.000000 is nan (c) 2008 Microchip Technology Inc. DS51456E-page 153 16-Bit Language Tools Libraries ceil Description: Calculates the ceiling of a value. Include: <math.h> Prototype: double ceil(double x); Argument: x Return Value: Returns the smallest integer value greater than or equal to x. Remarks: No domain or range error will occur. See floor. Example: #include <math.h> /* for ceil */ #include <stdio.h> /* for printf */ a floating-point value for which to return the ceiling. int main(void) { double x[8] = {2.0, 1.75, 1.5, 1.25, -2.0, -1.75, -1.5, -1.25}; double y; int i; for (i=0; i<8; i++) { y = ceil (x[i]); printf("The ceiling for } %f is %f\n", x[i], y); } Output: The ceiling The ceiling The ceiling The ceiling The ceiling The ceiling The ceiling The ceiling DS51456E-page 154 for for for for for for for for 2.000000 is 1.750000 is 1.500000 is 1.250000 is -2.000000 is -1.750000 is -1.500000 is -1.250000 is 2.000000 2.000000 2.000000 2.000000 -2.000000 -1.000000 -1.000000 -1.000000 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions ceilf Description: Calculates the ceiling of a value. Include: <math.h> Prototype: float ceilf(float x); Argument: x Return Value: Returns the smallest integer value greater than or equal to x. Remarks: No domain or range error will occur. See floorf. Example: #include <math.h> /* for ceilf */ #include <stdio.h> /* for printf */ floating-point value. int main(void) { float x[8] = {2.0F, 1.75F, 1.5F, 1.25F, -2.0F, -1.75F, -1.5F, -1.25F}; float y; int i; for (i=0; i<8; i++) { y = ceilf (x[i]); printf("The ceiling for } %f is %f\n", x[i], y); } Output: The ceiling The ceiling The ceiling The ceiling The ceiling The ceiling The ceiling The ceiling for for for for for for for for 2.000000 is 1.750000 is 1.500000 is 1.250000 is -2.000000 is -1.750000 is -1.500000 is -1.250000 is 2.000000 2.000000 2.000000 2.000000 -2.000000 -1.000000 -1.000000 -1.000000 cos Description: Calculates the trigonometric cosine function of a double precision floating-point value. Include: <math.h> Prototype: double cos (double x); Argument: x Return Value: Returns the cosine of x in radians in the ranges of -1 to 1 inclusive. Remarks: A domain error will occur if x is a NaN or infinity. Example: #include <math.h> /* for cos */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the cosine int main(void) { double x,y; (c) 2008 Microchip Technology Inc. DS51456E-page 155 16-Bit Language Tools Libraries cos (Continued) errno = 0; x = -1.0; y = cos (x); if (errno) perror("Error"); printf("The cosine of %f is %f\n\n", x, y); errno = 0; x = 0.0; y = cos (x); if (errno) perror("Error"); printf("The cosine of %f is %f\n\n", x, y); } Output: The cosine of -1.000000 is 0.540302 The cosine of 0.000000 is 1.000000 cosf Description: Calculates the trigonometric cosine function of a single precision floating-point value. Include: <math.h> Prototype: float cosf (float x); Argument: x Return Value: Returns the cosine of x in radians in the ranges of -1 to 1 inclusive. Remarks: A domain error will occur if x is a NaN or infinity. Example: #include <math.h> /* for cosf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the cosine int main(void) { float x, y; errno = 0; x = -1.0F; y = cosf (x); if (errno) perror("Error"); printf("The cosine of %f is %f\n\n", x, y); errno = 0; x = 0.0F; y = cosf (x); if (errno) perror("Error"); printf("The cosine of %f is %f\n\n", x, y); } DS51456E-page 156 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions cosf (Continued) Output: The cosine of -1.000000 is 0.540302 The cosine of 0.000000 is 1.000000 cosh Description: Calculates the hyperbolic cosine function of a double precision floating-point value. Include: <math.h> Prototype: double cosh (double x); Argument: x Return Value: Returns the hyperbolic cosine of x Remarks: A range error will occur if the magnitude of x is too large. Example: #include <math.h> /* for cosh */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the hyperbolic cosine int main(void) { double x, y; errno = 0; x = -1.5; y = cosh (x); if (errno) perror("Error"); printf("The hyperbolic cosine of %f is %f\n\n", x, y); errno = 0; x = 0.0; y = cosh (x); if (errno) perror("Error"); printf("The hyperbolic cosine of %f is %f\n\n", x, y); errno = 0; x = 720.0; y = cosh (x); if (errno) perror("Error"); printf("The hyperbolic cosine of %f is %f\n\n", x, y); } Output: The hyperbolic cosine of -1.500000 is 2.352410 The hyperbolic cosine of 0.000000 is 1.000000 Error: range error The hyperbolic cosine of 720.000000 is inf (c) 2008 Microchip Technology Inc. DS51456E-page 157 16-Bit Language Tools Libraries coshf Description: Calculates the hyperbolic cosine function of a single precision floating-point value. Include: <math.h> Prototype: float coshf (float x); Argument: x Return Value: Returns the hyperbolic cosine of x Remarks: A range error will occur if the magnitude of x is too large. Example: #include <math.h> /* for coshf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the hyperbolic cosine int main(void) { float x, y; errno = 0; x = -1.0F; y = coshf (x); if (errno) perror("Error"); printf("The hyperbolic cosine of %f is %f\n\n", x, y); errno = 0; x = 0.0F; y = coshf (x); if (errno) perror("Error"); printf("The hyperbolic cosine of %f is %f\n\n", x, y); errno = 0; x = 720.0F; y = coshf (x); if (errno) perror("Error"); printf("The hyperbolic cosine of %f is %f\n\n", x, y); } Output: The hyperbolic cosine of -1.000000 is 1.543081 The hyperbolic cosine of 0.000000 is 1.000000 Error: range error The hyperbolic cosine of 720.000000 is inf DS51456E-page 158 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions exp Description: Calculates the exponential function of x (e raised to the power x where x is a double precision floating-point value). Include: <math.h> Prototype: double exp (double x); Argument: x Return Value: Returns the exponential of x. On an overflow, exp returns inf and on an underflow exp returns 0. Remarks: A range error occurs if the magnitude of x is too large. Example: #include <math.h> /* for exp */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the exponential int main(void) { double x, y; errno = 0; x = 1.0; y = exp (x); if (errno) perror("Error"); printf("The exponential of %f is %f\n\n", x, y); errno = 0; x = 1E3; y = exp (x); if (errno) perror("Error"); printf("The exponential of %f is %f\n\n", x, y); errno = 0; x = -1E3; y = exp (x); if (errno) perror("Error"); printf("The exponential of %f is %f\n\n", x, y); } Output: The exponential of 1.000000 is 2.718282 Error: range error The exponential of 1000.000000 is inf Error: range error The exponential of -1000.000000 is 0.000000 (c) 2008 Microchip Technology Inc. DS51456E-page 159 16-Bit Language Tools Libraries expf Description: Calculates the exponential function of x (e raised to the power x where x is a single precision floating-point value). Include: <math.h> Prototype: float expf (float x); Argument: x Return Value: Returns the exponential of x. On an overflow, expf returns inf and on an underflow exp returns 0. Remarks: A range error occurs if the magnitude of x is too large. Example: #include <math.h> /* for expf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ floating-point value for which to return the exponential int main(void) { float x, y; errno = 0; x = 1.0F; y = expf (x); if (errno) perror("Error"); printf("The exponential of %f is %f\n\n", x, y); errno = 0; x = 1.0E3F; y = expf (x); if (errno) perror("Error"); printf("The exponential of %f is %f\n\n", x, y); errno = 0; x = -1.0E3F; y = expf (x); if (errno) perror("Error"); printf("The exponential of %f is %f\n\n", x, y); } Output: The exponential of 1.000000 is 2.718282 Error: range error The exponential of 1000.000000 is inf Error: range error The exponential of -1000.000000 is 0.000000 DS51456E-page 160 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions fabs Description: Calculates the absolute value of a double precision floating-point value. Include: <math.h> Prototype: double fabs(double x); Argument: x Return Value: Returns the absolute value of x. (A negative number is returned as positive, a positive number is unchanged.) Remarks: No domain or range error will occur. Example: #include <math.h> /* for fabs */ #include <stdio.h> /* for printf */ floating-point value for which to return the absolute value int main(void) { double x, y; x = 1.75; y = fabs (x); printf("The absolute value of %f is x = -1.5; y = fabs (x); printf("The absolute value of %f is %f\n", x, y); %f\n", x, y); } Output: The absolute value of 1.750000 is The absolute value of -1.500000 is 1.750000 1.500000 fabsf Description: Calculates the absolute value of a single precision floating-point value. Include: <math.h> Prototype: float fabsf(float x); Argument: x Return Value: Returns the absolute value of x. (A negative number is returned as positive, a positive number is unchanged.) Remarks: No domain or range error will occur. Example: #include <math.h> /* for fabsf */ #include <stdio.h> /* for printf */ floating-point value for which to return the absolute value int main(void) { float x,y; x = 1.75F; y = fabsf (x); printf("The absolute value of %f is x = -1.5F; y = fabsf (x); printf("The absolute value of %f is %f\n", x, y); %f\n", x, y); } Output: The absolute value of 1.750000 is The absolute value of -1.500000 is (c) 2008 Microchip Technology Inc. 1.750000 1.500000 DS51456E-page 161 16-Bit Language Tools Libraries floor Description: Calculates the floor of a double precision floating-point value. Include: <math.h> Prototype: double floor (double x); Argument: x Return Value: Returns the largest integer value less than or equal to x. Remarks: No domain or range error will occur. See ceil. Example: #include <math.h> /* for floor */ #include <stdio.h> /* for printf */ floating-point value for which to return the floor. int main(void) { double x[8] = {2.0, 1.75, 1.5, 1.25, -2.0, -1.75, -1.5, -1.25}; double y; int i; for (i=0; i<8; i++) { y = floor (x[i]); printf("The ceiling for %f is %f\n", x[i], y); } } Output: The floor The floor The floor The floor The floor The floor The floor The floor for for for for for for for for 2.000000 is 2.000000 1.750000 is 1.000000 1.500000 is 1.000000 1.250000 is 1.000000 -2.000000 is -2.000000 -1.750000 is -2.000000 -1.500000 is -2.000000 -1.250000 is -2.000000 floorf DS51456E-page 162 Description: Calculates the floor of a single precision floating-point value. Include: <math.h> Prototype: float floorf(float x); Argument: x Return Value: Returns the largest integer value less than or equal to x. Remarks: No domain or range error will occur. See ceilf. floating-point value. (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions floorf (Continued) Example: #include <math.h> /* for floorf */ #include <stdio.h> /* for printf */ int main(void) { float x[8] = {2.0F, 1.75F, 1.5F, 1.25F, -2.0F, -1.75F, -1.5F, -1.25F}; float y; int i; for (i=0; i<8; i++) { y = floorf (x[i]); printf("The floor for } %f is %f\n", x[i], y); } Output: The floor The floor The floor The floor The floor The floor The floor The floor for for for for for for for for 2.000000 is 1.750000 is 1.500000 is 1.250000 is -2.000000 is -1.750000 is -1.500000 is -1.250000 is 2.000000 1.000000 1.000000 1.000000 -2.000000 -2.000000 -2.000000 -2.000000 fmod Description: Calculates the remainder of x/y as a double precision value. Include: <math.h> Prototype: double fmod(double x, double y); Arguments: x a double precision floating-point value. y a double precision floating-point value. Return Value: Returns the remainder of x divided by y. Remarks: If y = 0, a domain error occurs. If y is non-zero, the result will have the same sign as x and the magnitude of the result will be less than the magnitude of y. Example: #include <math.h> /* for fmod */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ int main(void) { double x,y,z; errno = 0; x = 7.0; y = 3.0; z = fmod(x, y); if (errno) perror("Error"); printf("For fmod(%f, %f) the remainder is %f\n\n", x, y, z); (c) 2008 Microchip Technology Inc. DS51456E-page 163 16-Bit Language Tools Libraries fmod (Continued) errno = 0; x = 7.0; y = 7.0; z = fmod(x, y); if (errno) perror("Error"); printf("For fmod(%f, %f) the remainder is %f\n\n", x, y, z); errno = 0; x = -5.0; y = 3.0; z = fmod(x, y); if (errno) perror("Error"); printf("For fmod(%f, %f) the remainder is %f\n\n", x, y, z); errno = 0; x = 5.0; y = -3.0; z = fmod(x, y); if (errno) perror("Error"); printf("For fmod(%f, %f) the remainder is %f\n\n", x, y, z); errno = 0; x = -5.0; y = -5.0; z = fmod(x, y); if (errno) perror("Error"); printf("For fmod(%f, %f) the remainder is %f\n\n", x, y, z); errno = 0; x = 7.0; y = 0.0; z = fmod(x, y); if (errno) perror("Error"); printf("For fmod(%f, %f) the remainder is %f\n\n", x, y, z); } DS51456E-page 164 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions fmod (Continued) Output: For fmod(7.000000, 3.000000) the remainder is 1.000000 For fmod(7.000000, 7.000000) the remainder is 0.000000 For fmod(-5.000000, 3.000000) the remainder is -2.000000 For fmod(5.000000, -3.000000) the remainder is 2.000000 For fmod(-5.000000, -5.000000) the remainder is -0.000000 Error: domain error For fmod(7.000000, 0.000000) the remainder is nan fmodf Description: Calculates the remainder of x/y as a single precision value. Include: <math.h> Prototype: float fmodf(float x, float y); Arguments: x a single precision floating-point value y a single precision floating-point value Return Value: Returns the remainder of x divided by y. Remarks: If y = 0, a domain error occurs. If y is non-zero, the result will have the same sign as x and the magnitude of the result will be less than the magnitude of y. Example: #include <math.h> /* for fmodf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ int main(void) { float x,y,z; errno = 0; x = 7.0F; y = 3.0F; z = fmodf (x, y); if (errno) perror("Error"); printf("For fmodf (%f, %f) the remainder is" " %f\n\n", x, y, z); errno = 0; x = -5.0F; y = 3.0F; z = fmodf (x, y); if (errno) perror("Error"); printf("For fmodf (%f, %f) the remainder is" " %f\n\n", x, y, z); (c) 2008 Microchip Technology Inc. DS51456E-page 165 16-Bit Language Tools Libraries fmodf (Continued) errno = 0; x = 5.0F; y = -3.0F; z = fmodf (x, y); if (errno) perror("Error"); printf("For fmodf (%f, %f) the remainder is" " %f\n\n", x, y, z); errno = 0; x = 5.0F; y = -5.0F; z = fmodf (x, y); if (errno) perror("Error"); printf("For fmodf (%f, %f) the remainder is" " %f\n\n", x, y, z); errno = 0; x = 7.0F; y = 0.0F; z = fmodf (x, y); if (errno) perror("Error"); printf("For fmodf (%f, %f) the remainder is" " %f\n\n", x, y, z); errno = 0; x = 7.0F; y = 7.0F; z = fmodf (x, y); if (errno) perror("Error"); printf("For fmodf (%f, %f) the remainder is" " %f\n\n", x, y, z); } Output: For fmodf (7.000000, 3.000000) the remainder is 1.000000 For fmodf (-5.000000, 3.000000) the remainder is -2.000000 For fmodf (5.000000, -3.000000) the remainder is 2.000000 For fmodf (5.000000, -5.000000) the remainder is 0.000000 Error: domain error For fmodf (7.000000, 0.000000) the remainder is nan For fmodf (7.000000, 7.000000) the remainder is 0.000000 DS51456E-page 166 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions frexp Description: Gets the fraction and the exponent of a double precision floating-point number. Include: <math.h> Prototype: double frexp (double x, int *exp); Arguments: x floating-point value for which to return the fraction and exponent exp pointer to a stored integer exponent Return Value: Returns the fraction, exp points to the exponent. If x is 0, the function returns 0 for both the fraction and exponent. Remarks: The absolute value of the fraction is in the range of 1/2 (inclusive) to 1 (exclusive). No domain or range error will occur. Example: #include <math.h> /* for frexp */ #include <stdio.h> /* for printf */ int main(void) { double x,y; int n; x = 50.0; y = frexp (x, &n); printf("For frexp of %f\n the fraction is %f\n ", x, y); printf(" and the exponent is %d\n\n", n); x = -2.5; y = frexp (x, &n); printf("For frexp of %f\n the fraction is %f\n ", x, y); printf(" and the exponent is %d\n\n", n); x = 0.0; y = frexp (x, &n); printf("For frexp of %f\n the fraction is %f\n ", x, y); printf(" and the exponent is %d\n\n", n); } Output: For frexp of 50.000000 the fraction is 0.781250 and the exponent is 6 For frexp of -2.500000 the fraction is -0.625000 and the exponent is 2 For frexp of 0.000000 the fraction is 0.000000 and the exponent is 0 (c) 2008 Microchip Technology Inc. DS51456E-page 167 16-Bit Language Tools Libraries frexpf Description: Gets the fraction and the exponent of a single precision floating-point number. Include: <math.h> Prototype: float frexpf (float x, int *exp); Arguments: x floating-point value for which to return the fraction and exponent exp pointer to a stored integer exponent Return Value: Returns the fraction, exp points to the exponent. If x is 0, the function returns 0 for both the fraction and exponent. Remarks: The absolute value of the fraction is in the range of 1/2 (inclusive) to 1 (exclusive). No domain or range error will occur. Example: #include <math.h> /* for frexpf */ #include <stdio.h> /* for printf */ int main(void) { float x,y; int n; x = 0.15F; y = frexpf (x, &n); printf("For frexpf of %f\n the fraction is %f\n ", x, y); printf(" and the exponent is %d\n\n", n); x = -2.5F; y = frexpf (x, &n); printf("For frexpf of %f\n the fraction is %f\n ", x, y); printf(" and the exponent is %d\n\n", n); x = 0.0F; y = frexpf (x, &n); printf("For frexpf of %f\n the fraction is %f\n ", x, y); printf(" and the exponent is %d\n\n", n); } Output: For frexpf of 0.150000 the fraction is 0.600000 and the exponent is -2 For frexpf of -2.500000 the fraction is -0.625000 and the exponent is 2 For frexpf of 0.000000 the fraction is 0.000000 and the exponent is 0 DS51456E-page 168 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions ldexp Description: Calculates the result of a double precision floating-point number multiplied by an exponent of 2. Include: <math.h> Prototype: double ldexp(double x, int ex); Arguments: x floating-point value ex integer exponent Return Value: Returns x * 2^ex. On an overflow, ldexp returns inf and on an underflow, ldexp returns 0. Remarks: A range error will occur on overflow or underflow. Example: #include <math.h> /* for ldexp */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ int main(void) { double x,y; int n; errno = 0; x = -0.625; n = 2; y = ldexp (x, n); if (errno) perror("Error"); printf("For a number = %f and an exponent = %d\n", x, n); printf(" ldexp(%f, %d) = %f\n\n", x, n, y); errno = 0; x = 2.5; n = 3; y = ldexp (x, n); if (errno) perror("Error"); printf("For a number = %f and an exponent = %d\n", x, n); printf(" ldexp(%f, %d) = %f\n\n", x, n, y); errno = 0; x = 15.0; n = 10000; y = ldexp (x, n); if (errno) perror("Error"); printf("For a number = %f and an exponent = %d\n", x, n); printf(" ldexp(%f, %d) = %f\n\n", x, n, y); } (c) 2008 Microchip Technology Inc. DS51456E-page 169 16-Bit Language Tools Libraries ldexp (Continued) Output: For a number = -0.625000 and an exponent = 2 ldexp(-0.625000, 2) = -2.500000 For a number = 2.500000 and an exponent = 3 ldexp(2.500000, 3) = 20.000000 Error: range error For a number = 15.000000 and an exponent = 10000 ldexp(15.000000, 10000) = inf ldexpf Description: Calculates the result of a single precision floating-point number multiplied by an exponent of 2. Include: <math.h> Prototype: float ldexpf(float x, int ex); Arguments: x floating-point value ex integer exponent Return Value: Returns x * 2^ex. On an overflow, ldexp returns inf and on an underflow, ldexp returns 0. Remarks: A range error will occur on overflow or underflow. Example: #include <math.h> /* for ldexpf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ int main(void) { float x,y; int n; errno = 0; x = -0.625F; n = 2; y = ldexpf (x, n); if (errno) perror("Error"); printf("For a number = %f and an exponent = %d\n", x, n); printf(" ldexpf(%f, %d) = %f\n\n", x, n, y); errno = 0; x = 2.5F; n = 3; y = ldexpf (x, n); if (errno) perror("Error"); printf("For a number = %f and an exponent = %d\n", x, n); printf(" ldexpf(%f, %d) = %f\n\n", x, n, y); DS51456E-page 170 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions ldexpf (Continued) errno = 0; x = 15.0F; n = 10000; y = ldexpf (x, n); if (errno) perror("Error"); printf("For a number = %f and an exponent = %d\n", x, n); printf(" ldexpf(%f, %d) = %f\n\n", x, n, y); } Output: For a number = -0.625000 and an exponent = 2 ldexpf(-0.625000, 2) = -2.500000 For a number = 2.500000 and an exponent = 3 ldexpf(2.500000, 3) = 20.000000 Error: range error For a number = 15.000000 and an exponent = 10000 ldexpf(15.000000, 10000) = inf (c) 2008 Microchip Technology Inc. DS51456E-page 171 16-Bit Language Tools Libraries log Description: Calculates the natural logarithm of a double precision floating-point value. Include: <math.h> Prototype: double log(double x); Argument: x Return Value: Returns the natural logarithm of x. -inf is returned if x is 0 and NaN is returned if x is a negative number. Remarks: A domain error occurs if x 0. Example: #include <math.h> /* for log */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ any positive value for which to return the log int main(void) { double x, y; errno = 0; x = 2.0; y = log (x); if (errno) perror("Error"); printf("The natural logarithm of %f is %f\n\n", x, y); errno = 0; x = 0.0; y = log (x); if (errno) perror("Error"); printf("The natural logarithm of %f is %f\n\n", x, y); errno = 0; x = -2.0; y = log (x); if (errno) perror("Error"); printf("The natural logarithm of %f is %f\n\n", x, y); } Output: The natural logarithm of 2.000000 is 0.693147 The natural logarithm of 0.000000 is -inf Error: domain error The natural logarithm of -2.000000 is nan DS51456E-page 172 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions log10 Description: Calculates the base-10 logarithm of a double precision floating-point value. Include: <math.h> Prototype: double log10(double x); Argument: x Return Value: Returns the base-10 logarithm of x. -inf is returned if x is 0 and NaN is returned if x is a negative number. Remarks: A domain error occurs if x 0. Example: #include <math.h> /* for log10 */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ any double precision floating-point positive number int main(void) { double x, y; errno = 0; x = 2.0; y = log10 (x); if (errno) perror("Error"); printf("The base-10 logarithm of %f is %f\n\n", x, y); errno = 0; x = 0.0; y = log10 (x); if (errno) perror("Error"); printf("The base-10 logarithm of %f is %f\n\n", x, y); errno = 0; x = -2.0; y = log10 (x); if (errno) perror("Error"); printf("The base-10 logarithm of %f is %f\n\n", x, y); } Output: The base-10 logarithm of 2.000000 is 0.301030 The base-10 logarithm of 0.000000 is -inf Error: domain error The base-10 logarithm of -2.000000 is nan (c) 2008 Microchip Technology Inc. DS51456E-page 173 16-Bit Language Tools Libraries log10f Description: Calculates the base-10 logarithm of a single precision floating-point value. Include: <math.h> Prototype: float log10f(float x); Argument: x Return Value: Returns the base-10 logarithm of x. -inf is returned if x is 0 and NaN is returned if x is a negative number. Remarks: A domain error occurs if x 0. Example: #include <math.h> /* for log10f */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ any single precision floating-point positive number int main(void) { float x, y; errno = 0; x = 2.0F; y = log10f(x); if (errno) perror("Error"); printf("The base-10 logarithm of %f is %f\n\n", x, y); errno = 0; x = 0.0F; y = log10f(x); if (errno) perror("Error"); printf("The base-10 logarithm of %f is %f\n\n", x, y); errno = 0; x = -2.0F; y = log10f(x); if (errno) perror("Error"); printf("The base-10 logarithm of %f is %f\n\n", x, y); } Output: The base-10 logarithm of 2.000000 is 0.301030 Error: domain error The base-10 logarithm of 0.000000 is -inf Error: domain error The base-10 logarithm of -2.000000 is nan DS51456E-page 174 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions logf Description: Calculates the natural logarithm of a single precision floating-point value. Include: <math.h> Prototype: float logf(float x); Argument: x Return Value: Returns the natural logarithm of x. -inf is returned if x is 0 and NaN is returned if x is a negative number. Remarks: A domain error occurs if x 0. Example: #include <math.h> /* for logf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ any positive value for which to return the log int main(void) { float x, y; errno = 0; x = 2.0F; y = logf (x); if (errno) perror("Error"); printf("The natural logarithm of %f is %f\n\n", x, y); errno = 0; x = 0.0F; y = logf (x); if (errno) perror("Error"); printf("The natural logarithm of %f is %f\n\n", x, y); errno = 0; x = -2.0F; y = logf (x); if (errno) perror("Error"); printf("The natural logarithm of %f is %f\n\n", x, y); } Output: The natural logarithm of 2.000000 is 0.693147 The natural logarithm of 0.000000 is -inf Error: domain error The natural logarithm of -2.000000 is nan (c) 2008 Microchip Technology Inc. DS51456E-page 175 16-Bit Language Tools Libraries modf Description: Splits a double precision floating-point value into fractional and integer parts. Include: <math.h> Prototype: double modf(double x, double *pint); Arguments: x double precision floating-point value pint pointer to a stored the integer part Return Value: Returns the signed fractional part and pint points to the integer part. Remarks: The absolute value of the fractional part is in the range of 0 (inclusive) to 1 (exclusive). No domain or range error will occur. Example: #include <math.h> /* for modf */ #include <stdio.h> /* for printf */ int main(void) { double x,y,n; x = 0.707; y = modf (x, &n); printf("For %f the fraction is %f\n ", x, y); printf(" and the integer is %0.f\n\n", n); x = -15.2121; y = modf (x, &n); printf("For %f the fraction is %f\n ", x, y); printf(" and the integer is %0.f\n\n", n); } Output: For 0.707000 the fraction is 0.707000 and the integer is 0 For -15.212100 the fraction is -0.212100 and the integer is -15 DS51456E-page 176 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions modff Description: Splits a single precision floating-point value into fractional and integer parts. Include: <math.h> Prototype: float modff(float x, float *pint); Arguments: x single precision floating-point value pint pointer to stored integer part Return Value: Returns the signed fractional part and pint points to the integer part. Remarks: The absolute value of the fractional part is in the range of 0 (inclusive) to 1 (exclusive). No domain or range error will occur. Example: #include <math.h> /* for modff */ #include <stdio.h> /* for printf */ int main(void) { float x,y,n; x = 0.707F; y = modff (x, &n); printf("For %f the fraction is %f\n ", x, y); printf(" and the integer is %0.f\n\n", n); x = -15.2121F; y = modff (x, &n); printf("For %f the fraction is %f\n ", x, y); printf(" and the integer is %0.f\n\n", n); } Output: For 0.707000 the fraction is 0.707000 and the integer is 0 For -15.212100 the fraction is -0.212100 and the integer is -15 (c) 2008 Microchip Technology Inc. DS51456E-page 177 16-Bit Language Tools Libraries pow Description: Calculates x raised to the power y. Include: <math.h> Prototype: double pow(double x, double y); Arguments: x the base y the exponent Return Value: Returns x raised to the power y (x^y). Remarks: If y is 0, pow returns 1. If x is 0.0 and y is less than 0 pow returns inf and a domain error occurs. If the result overflows or underflows, a range error occurs. Example: #include <math.h> /* for pow */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ int main(void) { double x,y,z; errno = 0; x = -2.0; y = 3.0; z = pow (x, y); if (errno) perror("Error"); printf("%f raised to %f is %f\n\n ", x, y, z); errno = 0; x = 3.0; y = -0.5; z = pow (x, y); if (errno) perror("Error"); printf("%f raised to %f is %f\n\n ", x, y, z); errno = 0; x = 4.0; y = 0.0; z = pow (x, y); if (errno) perror("Error"); printf("%f raised to %f is %f\n\n ", x, y, z); errno = 0; x = 0.0; y = -3.0; z = pow (x, y); if (errno) perror("Error"); printf("%f raised to %f is %f\n\n ", x, y, z); } DS51456E-page 178 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions pow (Continued) Output: -2.000000 raised to 3.000000 is -8.000000 3.000000 raised to -0.500000 is 0.577350 4.000000 raised to 0.000000 is 1.000000 Error: domain error 0.000000 raised to -3.000000 is inf powf Description: Calculates x raised to the power y. Include: <math.h> Prototype: float powf(float x, float y); Arguments: x base y exponent Return Value: Returns x raised to the power y (x^y). Remarks: If y is 0, powf returns 1. If x is 0.0 and y is less than 0 powf returns inf and a domain error occurs. If the result overflows or underflows, a range error occurs. Example: #include <math.h> /* for powf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ int main(void) { float x,y,z; errno = 0; x = -2.0F; y = 3.0F; z = powf (x, y); if (errno) perror("Error"); printf("%f raised to %f is %f\n\n ", x, y, z); errno = 0; x = 3.0F; y = -0.5F; z = powf (x, y); if (errno) perror("Error"); printf("%f raised to %f is %f\n\n ", x, y, z); errno = 0; x = 0.0F; y = -3.0F; z = powf (x, y); if (errno) perror("Error"); printf("%f raised to %f is %f\n\n ", x, y, z); } (c) 2008 Microchip Technology Inc. DS51456E-page 179 16-Bit Language Tools Libraries powf (Continued) Output: -2.000000 raised to 3.000000 is -8.000000 3.000000 raised to -0.500000 is 0.577350 Error: domain error 0.000000 raised to -3.000000 is inf sin Description: Calculates the trigonometric sine function of a double precision floating-point value. Include: <math.h> Prototype: double sin (double x); Argument: x Return Value: Returns the sine of x in radians in the ranges of -1 to 1 inclusive. Remarks: A domain error will occur if t x is a NaN or infinity. Example: #include <math.h> /* for sin */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the sine int main(void) { double x, y; errno = 0; x = -1.0; y = sin (x); if (errno) perror("Error"); printf("The sine of %f is %f\n\n", x, y); errno = 0; x = 0.0; y = sin (x); if (errno) perror("Error"); printf("The sine of %f is %f\n\n", x, y); } Output: The sine of -1.000000 is -0.841471 The sine of 0.000000 is 0.000000 DS51456E-page 180 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions sinf Description: Calculates the trigonometric sine function of a single precision floating-point value. Include: <math.h> Prototype: float sinf (float x); Argument: x Return Value: Returns the sin of x in radians in the ranges of -1 to 1 inclusive. Remarks: A domain error will occur if x is a NaN or infinity. Example: #include <math.h> /* for sinf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the sine int main(void) { float x, y; errno = 0; x = -1.0F; y = sinf (x); if (errno) perror("Error"); printf("The sine of %f is %f\n\n", x, y); errno = 0; x = 0.0F; y = sinf (x); if (errno) perror("Error"); printf("The sine of %f is %f\n\n", x, y); } Output: The sine of -1.000000 is -0.841471 The sine of 0.000000 is 0.000000 (c) 2008 Microchip Technology Inc. DS51456E-page 181 16-Bit Language Tools Libraries sinh Description: Calculates the hyperbolic sine function of a double precision floating-point value. Include: <math.h> Prototype: double sinh (double x); Argument: x Return Value: Returns the hyperbolic sine of x Remarks: A range error will occur if the magnitude of x is too large. Example: #include <math.h> /* for sinh */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the hyperbolic sine int main(void) { double x, y; errno = 0; x = -1.5; y = sinh (x); if (errno) perror("Error"); printf("The hyperbolic sine of %f is %f\n\n", x, y); errno = 0; x = 0.0; y = sinh (x); if (errno) perror("Error"); printf("The hyperbolic sine of %f is %f\n\n", x, y); errno = 0; x = 720.0; y = sinh (x); if (errno) perror("Error"); printf("The hyperbolic sine of %f is %f\n\n", x, y); } Output: The hyperbolic sine of -1.500000 is -2.129279 The hyperbolic sine of 0.000000 is 0.000000 Error: range error The hyperbolic sine of 720.000000 is inf DS51456E-page 182 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions sinhf Description: Calculates the hyperbolic sine function of a single precision floating-point value. Include: <math.h> Prototype: float sinhf (float x); Argument: x Return Value: Returns the hyperbolic sine of x Remarks: A range error will occur if the magnitude of x is too large. Example: #include <math.h> /* for sinhf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the hyperbolic sine int main(void) { float x, y; errno = 0; x = -1.0F; y = sinhf (x); if (errno) perror("Error"); printf("The hyperbolic sine of %f is %f\n\n", x, y); errno = 0; x = 0.0F; y = sinhf (x); if (errno) perror("Error"); printf("The hyperbolic sine of %f is %f\n\n", x, y); } Output: The hyperbolic sine of -1.000000 is -1.175201 The hyperbolic sine of 0.000000 is 0.000000 (c) 2008 Microchip Technology Inc. DS51456E-page 183 16-Bit Language Tools Libraries sqrt Description: Calculates the square root of a double precision floating-point value. Include: <math.h> Prototype: double sqrt(double x); Argument: x Return Value: Returns the non-negative square root of x.. Remarks: If x is negative, a domain error occurs. Example: #include <math.h> /* for sqrt */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ a non-negative floating-point value int main(void) { double x, y; errno = 0; x = 0.0; y = sqrt (x); if (errno) perror("Error"); printf("The square root of %f is %f\n\n", x, y); errno = 0; x = 9.5; y = sqrt (x); if (errno) perror("Error"); printf("The square root of %f is %f\n\n", x, y); errno = 0; x = -25.0; y = sqrt (x); if (errno) perror("Error"); printf("The square root of %f is %f\n\n", x, y); } Output: The square root of 0.000000 is 0.000000 The square root of 9.500000 is 3.082207 Error: domain error The square root of -25.000000 is nan DS51456E-page 184 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions sqrtf Description: Calculates the square root of a single precision floating-point value. Include: <math.h> Prototype: float sqrtf(float x); Argument: x Return Value: Returns the non-negative square root of x. Remarks: If x is negative, a domain error occurs. Example: #include <math.h> /* for sqrtf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ non-negative floating-point value int main(void) { double x; errno = 0; x = sqrtf (0.0F); if (errno) perror("Error"); printf("The square root of 0.0F is %f\n\n", x); errno = 0; x = sqrtf (9.5F); if (errno) perror("Error"); printf("The square root of 9.5F is %f\n\n", x); errno = 0; x = sqrtf (-25.0F); if (errno) perror("Error"); printf("The square root of -25F is %f\n", x); } Output: The square root of 0.0F is 0.000000 The square root of 9.5F is 3.082207 Error: domain error The square root of -25F is nan (c) 2008 Microchip Technology Inc. DS51456E-page 185 16-Bit Language Tools Libraries tan Description: Calculates the trigonometric tangent function of a double precision floating-point value. Include: <math.h> Prototype: double tan (double x); Argument: x Return Value: Returns the tangent of x in radians. Remarks: A domain error will occur if x is a NaN or infinity. Example: #include <math.h> /* for tan */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the tangent int main(void) { double x, y; errno = 0; x = -1.0; y = tan (x); if (errno) perror("Error"); printf("The tangent of %f is %f\n\n", x, y); errno = 0; x = 0.0; y = tan (x); if (errno) perror("Error"); printf("The tangent of %f is %f\n\n", x, y); } Output: The tangent of -1.000000 is -1.557408 The tangent of 0.000000 is 0.000000 tanf Description: Calculates the trigonometric tangent function of a single precision floating-point value. Include: <math.h> Prototype: float tanf (float x); Argument: x Return Value: Returns the tangent of x Remarks: A domain error will occur if x is a NaN or infinity. Example: #include <math.h> /* for tanf */ #include <stdio.h> /* for printf, perror */ #include <errno.h> /* for errno */ value for which to return the tangent int main(void) { float x, y; DS51456E-page 186 (c) 2008 Microchip Technology Inc. Standard C Libraries - Math Functions tanf (Continued) errno = 0; x = -1.0F; y = tanf (x); if (errno) perror("Error"); printf("The tangent of %f is %f\n\n", x, y); errno = 0; x = 0.0F; y = tanf (x); if (errno) perror("Error"); printf("The tangent of %f is %f\n", x, y); } Output: The tangent of -1.000000 is -1.557408 The tangent of 0.000000 is 0.000000 tanh Description: Calculates the hyperbolic tangent function of a double precision floating-point value. Include: <math.h> Prototype: double tanh (double x); Argument: x Return Value: Returns the hyperbolic tangent of x in the ranges of -1 to 1 inclusive. Remarks: No domain or range error will occur. Example: #include <math.h> /* for tanh */ #include <stdio.h> /* for printf */ value for which to return the hyperbolic tangent int main(void) { double x, y; x = -1.0; y = tanh (x); printf("The hyperbolic tangent of %f is %f\n\n", x, y); x = 2.0; y = tanh (x); printf("The hyperbolic tangent of %f is %f\n\n", x, y); } Output: The hyperbolic tangent of -1.000000 is -0.761594 The hyperbolic tangent of 2.000000 is 0.964028 (c) 2008 Microchip Technology Inc. DS51456E-page 187 16-Bit Language Tools Libraries tanhf Description: Calculates the hyperbolic tangent function of a single precision floating-point value. Include: <math.h> Prototype: float tanhf (float x); Argument: x Return Value: Returns the hyperbolic tangent of x in the ranges of -1 to 1 inclusive. Remarks: No domain or range error will occur. Example: #include <math.h> /* for tanhf */ #include <stdio.h> /* for printf */ value for which to return the hyperbolic tangent int main(void) { float x, y; x = -1.0F; y = tanhf (x); printf("The hyperbolic tangent of %f is %f\n\n", x, y); x = 0.0F; y = tanhf (x); printf("The hyperbolic tangent of %f is %f\n\n", x, y); } Output: The hyperbolic tangent of -1.000000 is -0.761594 The hyperbolic tangent of 0.000000 is 0.000000 DS51456E-page 188 (c) 2008 Microchip Technology Inc. 16-BIT LANGUAGE TOOLS LIBRARIES Chapter 4. Standard C Libraries - Support Functions 4.1 INTRODUCTION This chapter describes support functions that either must be customized for correct operation of the Standard C Library in your target environment or are already customized for a Microchip target environment. The default behavior section describes what the function does as it is distributed. The description and remarks describe what it typically should do. The corresponding object modules are distributed in the libpic30-omf.a archive and the source code (for the compiler) is available in the src\pic30 folder. 4.1.1 Assembly Code Applications A free version of this library and its associated header file is available from the Microchip web site. Source code is included. 4.1.2 C Code Applications The MPLAB C Compiler for PIC24 MCUs and dsPIC(R) DSCs (formerly MPLAB C30) install directory (c:\Program Files\Microchip\MPLAB C30) contains the following subdirectories with library-related files: * lib - standard C library files * src\pic30 - source code for library functions, batch file to rebuild the library * support\h - header files for libraries In addition, there is a file, ResourceGraphs.pdf, which contains diagrams of resources used by each function, located in lib. 4.1.3 Chapter Organization This chapter is organized as follows: * * * * * * * Using the Support Functions Standard C Library Helper Functions Standard C Library Functions That Require Modification Functions/Constants to Support A Simulated UART Functions for Erasing and Writing EEDATA Memory Functions for Erasing and Writing Flash Memory Functions for Specialized Copying and Initialization (c) 2008 Microchip Technology Inc. DS51456E-page 189 16-Bit Language Tools Libraries 4.2 USING THE SUPPORT FUNCTIONS Building an application which utilizes the support functions requires two types of files: header files and library files. * Rebuilding the libpic30-omf.a library 4.2.1 Header Files All standard C library entities are declared or defined in one or more standard headers (See list in Section 4.1.3 "Chapter Organization".) To make use of a library entity in a program, write an include directive that names the relevant standard header. The contents of a standard header is included by naming it in an include directive, as in: #include <libpic30.h> /* include dsPIC30F facilities */ The standard headers can be included in any order. Do not include a standard header within a declaration. Do not define macros that have the same names as keywords before including a standard header. A standard header never includes another standard header. 4.2.2 Library Files The archived library files contain all the individual object files for each library function. When linking an application, the library file must be provided as an input to the linker (using the --library or -l linker option) such that the functions used by the application may be linked into the application. A typical C application will require three library files: libc-omf.a, libm-omf.a, and libpic30-omf.a. (See Section 1.2 "OMF-Specific Libraries/Start-up Modules" for more on OMF-specific libraries.) These libraries will be included automatically if linking is performed using the compiler. Note: 4.2.3 Some standard library functions require a heap. These include the standard I/O functions that open files and the memory allocation functions. See the "MPLAB(R) Assembler, Linker and Utilities for PIC24 MCUs and dsPIC(R) DSCs User's Guide" (DS51317) and "MPLAB(R) C Compiler for PIC24 MCUs and dsPIC(R) DSCs User's Guide" (DS51284) for more information on the heap. Rebuilding the libpic30-omf.a library By default, the helper functions listed in this chapter were written to work with the sim30 simulator. The header file, simio.h, defines the interface between the library and the simulator. It is provided so you can rebuild the libraries and continue to use the simulator. However, your application should not use this interface since the simulator will not be available to an embedded application. The helper functions must be modified and rebuilt for your target application. The libpic30-omf.a library can be rebuild with the batch file named makelib.bat, which has been provided with the sources in src\pic30. Execute the batch file from a command window. Be sure you are in the src\pic30 directory. Then copy the newly compiled file (libpic30-omf.a) into the lib directory. DS51456E-page 190 (c) 2008 Microchip Technology Inc. Standard C Libraries - Support Functions 4.3 STANDARD C LIBRARY HELPER FUNCTIONS These functions are called by other functions in the standard C library and must be modified for the target application. The corresponding object modules are distributed in the libpic30-omf.a archive and the source code (for the compiler) is available in the src\pic30 folder. _exit Description: Terminate program execution. Include: None Prototype: void _exit (int status); Argument: status Remarks: This is a helper function called by the exit() Standard C Library function. Default Behavior: As distributed, this function flushes stdout and terminates. The parameter status is the same as that passed to the exit() standard C library function. File: _exit.c exit status brk Description: Set the end of the process's data space. Include: None Prototype: int brk(void *endds); Argument: endds Return Value: Returns `0' if successful, `-1' if not. Remarks: brk() is used to dynamically change the amount of space allocated for the calling process's data segment. The change is made by resetting the process's break value and allocating the appropriate amount of space. The break value is the address of the first location beyond the end of the data segment. The amount of allocated space increases as the break value increases. Newly allocated space is uninitialized. This helper function is used by the Standard C Library function malloc(). (c) 2008 Microchip Technology Inc. pointer to the end of the data segment DS51456E-page 191 16-Bit Language Tools Libraries brk (Continued) Default Behavior: If the argument endds is zero, the function sets the global variable __curbrk to the address of the start of the heap, and returns zero. If the argument endds is non-zero, and has a value less than the address of the end of the heap, the function sets the global variable __curbrk to the value of endds and returns zero. Otherwise, the global variable __curbrk is unchanged, and the function returns -1. The argument endds must be within the heap range (see data space memory map below). PSV Stack Heap Variables SFR Notice that, since the stack is located immediately above the heap, using brk() or sbrk() has little effect on the size of the dynamic memory pool. The brk() and sbrk() functions are primarily intended for use in run-time environments where the stack grows downward and the heap grows upward. The linker allocates a block of memory for the heap if the -Wl,--heap=n option is specified, where n is the desired heap size in characters. The starting and ending addresses of the heap are reported in variables _heap and _eheap, respectively. For the 16-bit compiler, using the linker's heap size option is the standard way of controlling heap size, rather than relying on brk() and sbrk(). File: brk.c close DS51456E-page 192 Description: Close a file. Include: None Prototype: int close(int handle); Argument: handle Return Value: Returns `0' if the file is successfully closed. A return value of `-1' indicates an error. Remarks: This helper function is called by the fclose() Standard C Library function. Default Behavior: As distributed, this function passes the file handle to the simulator, which issues a close in the host file system. File: close.c handle referring to an opened file (c) 2008 Microchip Technology Inc. Standard C Libraries - Support Functions lseek Description: Move a file pointer to a specified location. Include: None Prototype: long lseek(int handle, long offset, int origin); Argument: handle offset origin Return Value: Returns the offset, in characters, of the new position from the beginning of the file. A return value of `-1L' indicates an error. Remarks: This helper function is called by the Standard C Library functions fgetpos(), ftell(), fseek(), fsetpos, and rewind(). Default Behavior: As distributed, the parameters are passed to the host file system through the simulator. The return value is the value returned by the host file system. File: lseek.c refers to an opened file the number of characters from the origin the position from which to start the seek. origin may be one of the following values (as defined in stdio.h): SEEK_SET - Beginning of file. SEEK_CUR - Current position of file pointer. SEEK_END - End-of-file. open Description: Open a file. Include: None Prototype: int open(const char *name, int access, int mode); Argument: name access mode Return Value: If successful, the function returns a file handle, a small positive integer. This handle is then used on subsequent low-level file I/O operations. A return value of `-1' indicates an error. Remarks: The access flag is a union of one of the following access methods and zero or more access qualifiers: 0 - Open a file for reading. 1 - Open a file for writing. 2 - Open a file for both reading and writing. The following access qualifiers must be supported: 0x0008 - Move file pointer to end-of-file before every write operation. 0x0100 - Create and open a new file for writing. 0x0200 - Open the file and truncate it to zero length. 0x4000 - Open the file in text (translated) mode. 0x8000 - Open the file in binary (untranslated) mode. The mode parameter may be one of the following: 0x0100 - Reading only permitted. 0x0080 - Writing permitted (implies reading permitted). This helper function is called by the Standard C Library functions fopen() and freopen(). Default Behavior: As distributed, the parameters are passed to the host file system through the simulator. The return value is the value returned by the host file system. If the host system returns a value of `-1', the global variable errno is set to the value of the symbolic constant EFOPEN defined in <errno.h>. File: open.c (c) 2008 Microchip Technology Inc. name of the file to be opened access method to open file type of access permitted DS51456E-page 193 16-Bit Language Tools Libraries read Description: Read data from a file. Include: None Prototype: int read(int handle, void *buffer, unsigned int len); Argument: handle buffer len Return Value: Returns the number of characters read, which may be less than len if there are fewer than len characters left in the file or if the file was opened in text mode, in which case each carriage return-linefeed (CR-LF) pair is replaced with a single linefeed character. Only the single linefeed character is counted in the return value. The replacement does not affect the file pointer. If the function tries to read at end-of-file, it returns `0'. If the handle is invalid, or the file is not open for reading, or the file is locked, the function returns `-1'. Remarks: This helper function is called by the Standard C Library functions fgetc(), fgets(), fread(), and gets(). Default Behavior: As distributed, the parameters are passed to the host file system through the simulator. The return value is the value returned by the host file system. File: read.c handle referring to an opened file points to the storage location for read data the maximum number of characters to read sbrk DS51456E-page 194 Description: Extend the process' data space by a given increment. Include: None Prototype: void * sbrk(int incr); Argument: incr Return Value: Return the start of the new space allocated, or `-1' for errors. Remarks: sbrk() adds incr characters to the break value and changes the allocated space accordingly. incr can be negative, in which case the amount of allocated space is decreased. sbrk() is used to dynamically change the amount of space allocated for the calling process's data segment. The change is made by resetting the process's break value and allocating the appropriate amount of space. The break value is the address of the first location beyond the end of the data segment. The amount of allocated space increases as the break value increases. This is a helper function called by the Standard C Library function malloc(). Default Behavior: If the global variable __curbrk is zero, the function calls brk() to initialize the break value. If brk() returns -1, so does this function. If the incr is zero, the current value of the global variable __curbrk is returned. If the incr is non-zero, the function checks that the address (__curbrk + incr) is less than the end address of the heap. If it is less, the global variable __curbrk is updated to that value, and the function returns the unsigned value of __curbrk. Otherwise, the function returns -1. See the description of brk(). File: sbrk.c number of characters to increment/decrement (c) 2008 Microchip Technology Inc. Standard C Libraries - Support Functions write Description: Write data to a file. Include: None Prototype: int write(int handle, void *buffer, unsigned int count); Argument: handle buffer count Return Value: If successful, write returns the number of characters actually written. A return value of `-1' indicates an error. Remarks: If the actual space remaining on the disk is less than the size of the buffer the function is trying to write to the disk, write fails and does not flush any of the buffer's contents to the disk. If the file is opened in text mode, each linefeed character is replaced with a carriage return - linefeed pair in the output. The replacement does not affect the return value. This is a helper function called by the Standard C Library function fflush(). Default Behavior: As distributed, the parameters are passed to the host file system through the simulator. The return value is the value returned by the host file system. File: write.c (c) 2008 Microchip Technology Inc. refers to an opened file points to the storage location of data to be written the number of characters to write. DS51456E-page 195 16-Bit Language Tools Libraries 4.4 STANDARD C LIBRARY FUNCTIONS THAT REQUIRE MODIFICATION Although these functions are part of the standard C library, the object modules are distributed in the libpic30-omf.a archive and the source code (for the compiler) is available in the src\pic30 folder. These modules are not distributed as part of libc-omf.a. getenv Description: Get a value for an environment variable Include: <stdlib.h> Prototype: char *getenv(const char *s); Argument: s Return Value: Returns a pointer to the value of the environment variable if successful; otherwise, returns a null pointer. Default Behavior: As distributed, this function returns a null pointer. There is no support for environment variables. File: getenv.c name of environment variable remove Description: Remove a file. Include: <stdio.h> Prototype: int remove(const char *filename); Argument: filename Return Value: Returns `0' if successful, `-1' if unsuccessful. Default Behavior: As distributed, the parameters are passed to the host file system through the simulator. The return value is the value returned by the host file system. File: remove.c file to be removed rename Description: Rename a file or directory. Include: <stdio.h> Prototype: int rename(const char *oldname, const char *newname); Argument: oldname newname Return Value: Returns `0' if it is successful. On an error, the function returns a non-zero value. Default Behavior: As distributed, the parameters are passed to the host file system through the simulator. The return value is the value returned by the host file system. File: rename.c pointer to the old name pointer to the new name system DS51456E-page 196 Description: Execute a command. Include: <stdlib.h> Prototype: int system(const char *s); Argument: s command to be executed. (c) 2008 Microchip Technology Inc. Standard C Libraries - Support Functions system (Continued) Default Behavior: As distributed, this function acts as a stub or placeholder for your function. If s is not NULL, an error message is written to stdout and the program will reset; otherwise, a value of -1 is returned. File: system.c time 4.5 Description: Get the system time. Include: <time.h> Prototype: time_t time(time_t *timer); Argument: timer Return Value: Returns the elapse time in seconds. There is no error return. Default Behavior: As distributed, if timer2 is not enabled, it is enabled in 32-bit mode. The return value is the current value of the 32-bit timer2 register. Except in very rare cases, this return value is not the elapsed time in seconds. File: time.c points to a storage location for time FUNCTIONS/CONSTANTS TO SUPPORT A SIMULATED UART These functions and constants support UART functionality in MPLAB SIM simulator. __attach_input_file Description: Attach a hosted file to the standard input stream. Include: <libpic30.h> Prototype: int __attach_input_file(const char *p); Argument: p Remarks: This function differs from the MPLAB IDE mechanism of providing an input file because it provides "on-demand" access to the file. That is, data will only be read from the file upon request and the asynchronous nature of the UART is not simulated. This function may be called more than once; any opened file will be closed. It is only appropriate to call this function in a simulated environment. Default Behavior: Allows the programmer to attach a hosted file to the standard input stream, stdin. The function will return 0 to indicate failure. If the file cannot be opened for whatever reason, standard in will remain connected (or be re-connected) to the simulated UART. File: __attach_input_file.c pointer to file __close_input_file Description: Close a previously attached file. Include: <libpic30.h> Prototype: void __close_input_file(void); Argument: None Remarks: None. Default Behavior: This function will close a previously attached file and re-attach stdin to the simulated UART. This should occur before a reset to ensure that the file can be re-opened. File: __close_input_file.c (c) 2008 Microchip Technology Inc. DS51456E-page 197 16-Bit Language Tools Libraries __delay32 Description: Produce a delay of a specified number of clock cycles. Include: <libpic30.h> Prototype: void __delay32(unsigned long cycles); Argument: cycles Remarks: None. Default Behavior: This function will effect a delay of the requested number of cycles. The minimum supported delay is 11 cycles (an argument of less than 11 will result in 11 cycles). The delay includes the call and return statements, but not any cycles required to set up the arugment (typically this would be two for a literal value). File: __delay32.c number of cycles to delay. __C30_UART Description: Constant that defines the default UART. Include: N/A Prototype: int __C30_UART; Argument: N/A Return Value: N/A Remarks: Defines the default UART that read() and write() will use for stdin (unless a file has been attached), stdout, and stdout. Default Behavior: By default, or with a value of 1, UART 1 will be used. Otherwise UART 2 will be used. read() and write() are the eventual destinations of the C standard I/O functions. File: N/A Examples of Use EXAMPLE 4-1: UART1 I/O #include <libpic30.h> /* a new header file for these defintions */ #include <stdio.h> void main() { if (__attach_input_file("foo.txt")) { while (!feof(stdin)) { putchar(getchar()); } __close_input_file(); } } EXAMPLE 4-2: USING UART2 /* This program flashes a light and transmits a lot of messages at 9600 8n1 through uart 2 using the default stdio provided by the 16-bit compiler. This is for a dsPIC33F DSC on an Explorer 16(tm) board (and isn't very pretty) */ #include <libpic30.h> /* a new header file for these defintions */ #include <stdio.h> DS51456E-page 198 (c) 2008 Microchip Technology Inc. Standard C Libraries - Support Functions #ifndef __dsPIC33F__ #error this is a 33F demo for the explorer 16(tm) board #endif #inlcude <p33Fxxxx.h> _FOSCSEL(FNOSC_PRI ); _FOSC(FCKSM_CSDCMD & OSCIOFNC_OFF & POSCMD_XT); _FWDT(FWDTEN_OFF); main() { ODCA = 0; TRISAbits.TRISA6 = 0; __C30_UART=2; U2BRG = 38; U2MODEbits.UARTEN = 1; while (1) { __builtin_btg(&LATA,6); printf("Hello world %d\n",U2BRG); } } 4.6 FUNCTIONS FOR ERASING AND WRITING EEDATA MEMORY These functions support the erasing and writing of EEDATA memory for devices that have this type of memory. _erase_eedata Description: Erase EEDATA memory on dsPIC30F devices. Include: <libpic30.h> Prototype: void _erase_eedata(_prog_addressT dst, int len); Argument: dst len Return Value: None. Remarks: None. Default Behavior: Erase EEDATA memory as specified by parameters. File: _erase_eedata.c destination memory address length may be _EE_WORD or _EE_ROW (bytes) _erase_eedata_all Description: Erase the entire range of EEDATA memory on dsPIC30F devices. Include: <libpic30.h> Prototype: void _erase_eedata_all(void); Argument: None. Return Value: None. Remarks: None. Default Behavior: Erase all EEDATA memory for the selected device. File: _erase_eedata_all.c (c) 2008 Microchip Technology Inc. DS51456E-page 199 16-Bit Language Tools Libraries _wait_eedata Description: Wait for an erase or write operation to complete. Include: <libpic30.h> Prototype: void _wait_eedata(void); Argument: None. Return Value: None. Remarks: None. Default Behavior: Wait for an erase or write operation to complete. File: _wait_eedata.c _write_eedata_word Description: Write 16 bits of EEDATA memory on dsPIC30F devices. Include: <libpic30.h> Prototype: void _write_eedata_word(_prog_addressT dst, int dat); Argument: dst dat Return Value: None. Remarks: None. Default Behavior: Write one word of EEDATA memory for dsPIC30F devices. File: _write_eedata_word.c destination memory address integer data to be written _write_eedata_row Description: Write _EE_ROW bytes of EEDATA memory on dsPIC30F devices. Include: <libpic30.h> Prototype: void _write_eedata_row(_prog_addressT dst, int *src); Argument: dst *src Return Value: None. Remarks: None. Default Behavior: Write specified bytes of EEDATA memory. File: _write_eedata_row.c destination memory address points to the storage location of data to be written Example of Use #include "libpic30.h" #include "p30fxxxx.h" char __attribute__((space(eedata), aligned(_EE_ROW))) dat[_EE_ROW]; int main() { char i,source[_EE_ROW]; _prog_addressT p; DS51456E-page 200 for (i = 0; i < _EE_ROW; ) source[i] = i++; /* initialize some data */ _init_prog_address(p, dat); /* get address in program space */ (c) 2008 Microchip Technology Inc. Standard C Libraries - Support Functions _erase_eedata(p, _EE_ROW); /* erase a row */ _wait_eedata(); /* wait for operation to complete */ _write_eedata_row(p, source); /* write a row */ } 4.7 FUNCTIONS FOR ERASING AND WRITING FLASH MEMORY These functions support the erasing and writing of Flash memory for devices that have this type of memory. _erase_flash Description: Erase a page of FLASH memory. The length of a page is _FLASH_PAGE words (1 word = 3 bytes = 2 PC address units.) Include: <libpic30.h> Prototype: void _erase_flash(_prog_addressT dst); Argument: dst Return Value: None. Remarks: None. Default Behavior: Erase a page of FLASH memory. File: _erase_flash.c destination memory address _write_flash16 Description: Write a row of FLASH memory with 16-bit data. The length of a row is _FLASH_ROW words. The upper byte of each destination word is filled with 0xFF. Note that the row must be erased before any write can be successful. Include: <libpic30.h> Prototype: void _write_flash16(_prog_addressT dst, int *src); Argument: dst *src Return Value: None. Remarks: None. Default Behavior: Write a row of FLASH memory with 16-bit data. File: _write_flash16.c destination memory address points to the storage location of data to be written _write_flash24 Description: Write a row of FLASH memory with 24-bit data. The length of a row is _FLASH_ROW words. Note that the row must be erased before any write can be successful. Include: <libpic30.h> Prototype: void _write_flash24(_prog_addressT dst, int *src); Argument: dst *src Return Value: None. Remarks: None. (c) 2008 Microchip Technology Inc. destination memory address points to the storage location of data to be written DS51456E-page 201 16-Bit Language Tools Libraries _write_flash24 (Continued) Default Behavior: Write a row of FLASH memory with 24-bit data. File: _write_flash24.c _write_flash_word16 Description: Write a word of FLASH memory with 16-bit data. The upper byte of the destination word is filled with 0xFF. Note that the word must be erased before any write can be successful. This function is currently available only for PIC24F devices. Include: <libpic30.h> Prototype: void _write_flash_word16(_prog_addressT dst, int dat); Argument: dst dat Return Value: None. Remarks: None. Default Behavior: Write a word of FLASH memory with 16-bit data for PIC24 devices. File: _write_flash_word16.c destination memory address integer data to be written _write_flash_word24 Description: Write a word of FLASH memory with 24-bit data. Note that the word must be erased before any write can be successful. This function is currently available only for PIC24F devices. Include: <libpic30.h> Prototype: void _write_flash_word24(_prog_addressT dst, int dat); Argument: dst dat Return Value: None. Remarks: None. Default Behavior: Write a word of FLASH memory with 24-bit data for PIC24 devices. File: _write_flash_word24.c destination memory address integer data to be written Example of Use #include "libpic30.h" #include "p24Fxxxx.h" int __attribute__((space(prog),aligned(_FLASH_PAGE*2))) dat[_FLASH_PAGE]; int main() { int i; int source1[_FLASH_ROW]; long source2[_FLASH_ROW]; _prog_addressT p; for (i = 0; i < _FLASH_ROW; ) { source1[i] = i; source2[i] = i++; DS51456E-page 202 (c) 2008 Microchip Technology Inc. Standard C Libraries - Support Functions } /* initialize some data */ _init_prog_address(p, dat); /* get address in program space */ _erase_flash(p); /* erase a page */ _write_flash16(p, source1); /* write first row with 16-bit data */ #if defined (__dsPIC30F__) _erase_flash(p); #else p.next += (_FLASH_ROW * 2); #endif _write_flash24(p, source2); /* on dsPIC30F, only 1 row per page */ /* advance to next row */ /* write second row with 24-bit data */ } 4.8 FUNCTIONS FOR SPECIALIZED COPYING AND INITIALIZATION These functions support specialized data copying and initialization. _memcpy_p2d16 Description: Copy 16 bits of data from each address in program memory to data memory. The next unused source address is returned. Include: <libpic30.h> Prototype: _prog_addressT _memcpy_p2d16(char *dest, _prog_addressT src, unsigned int len); Argument: *dest src len Return Value: The next usused source address. Remarks: None. Default Behavior: Copy 16 bits of data from each address in program memory to data memory. File: _memcpy_p2d16.c pointer to destination memory address address of data to be written length of program memory _memcpy_p2d24 Description: Copy 24 bits of data from each address in program memory to data memory. The next unused source address is returned. Include: <libpic30.h> Prototype: _prog_addressT _memcpy_p2d24(char *dest, _prog_addressT src, unsigned int len); Argument: *dest src len Return Value: The next usused source address. Remarks: None. Default Behavior: Copy 24 bits of data from each address in program memory to data memory. File: _memcpy_p2d24.c (c) 2008 Microchip Technology Inc. pointer to destination memory address address of data to be written length of program memory DS51456E-page 203 16-Bit Language Tools Libraries _strncpy_p2d16 Description: Copy 16 bits of data from each address in program memory to data memory. The operation terminates early if a NULL char is copied. The next unused source address is returned. Include: <libpic30.h> Prototype: _prog_addressT _strncpy_p2d16(char *dest, _prog_addressT src, unsigned int len); Argument: *dest src len Return Value: The next usused source address. Remarks: None. Default Behavior: Copy 16 bits of data from each address in program memory to data memory. File: _strncpy_p2d16.c pointer to destination memory address address of data to be written length of program memory _strncpy_p2d24 Description: Copy 24 bits of data from each address in program memory to data memory. The operation terminates early if a NULL char is copied. The next unused source address is returned. Include: <libpic30.h> Prototype: _prog_addressT _strncpy_p2d24(char *dest, _prog_addressT src, unsigned int len); Argument: *dest src len Return Value: The next usused source address. Remarks: None. Default Behavior: Copy 24 bits of data from each address in program memory to data memory. File: _strncpy_p2d24.c pointer to destination memory address address of data to be written length of program memory _init_prog_address DS51456E-page 204 Description: A macro that is used to initialize variables of type _prog_addressT. These variables are not equivalent to C pointers. Include: <libpic30.h> Prototype: _init_prog_address(a,b); Argument: a b Return Value: N/A Remarks: None. Default Behavior: Initialize variable to specified value. File: _init_prog_address.c variable of type _prog_addressT initialization value for variable a (c) 2008 Microchip Technology Inc. Standard C Libraries - Support Functions Example of Use #include "stdio.h" #include "libpic30.h" void display_mem(char *p, unsigned int len) { int i; for (i = 0; i < len; i++) { printf(" %d", *p++); } printf("\n"); } char __attribute__((space(prog))) dat[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; char buf[10]; int main() { int i; _prog_addressT p; /* method 1 */ _init_prog_address(p, dat); (void) _memcpy_p2d16(buf, p, 10); display_mem(buf,10); /* method 2 */ _init_prog_address(p, dat); p = _memcpy_p2d16(buf, p, 4); p = _memcpy_p2d16(&buf[4], p, 6); display_mem(buf,10); } (c) 2008 Microchip Technology Inc. DS51456E-page 205 16-Bit Language Tools Libraries NOTES: DS51456E-page 206 (c) 2008 Microchip Technology Inc. 16-BIT LANGUAGE TOOLS LIBRARIES Chapter 5. Fixed Point Math Functions 5.1 INTRODUCTION Fixed point library math functions are contained in the files libq-omf.a (standard) and libq-dsp-omf.a (DSP), where omf will be coff or elf depending upon the selected object module format. The header file is named libq.h and is the same for standard or DSP versions of the library. 5.1.1 Assembly Code Applications A free version of the math functions library and header file is available from the Microchip web site. 5.1.2 C Code Applications The MPLAB C Compiler for PIC24 MCUs and dsPIC(R) DSCs (formerly MPLAB C30) install directory (c:\Program Files\Microchip\MPLAB C30) contains the following subdirectories with library-related files: * lib - standard C library files * support\h - header files for libraries In addition, there is a file, ResourceGraphs.pdf, which contains diagrams of resources used by each function, located in lib. 5.1.3 Chapter Organization This chapter is organized as follows: * Using the Fixed Point Libraries * <libq.h> mathematical functions 5.2 USING THE FIXED POINT LIBRARIES Building an application which utilizes the fixed point libraries requires two types of files: header files and library files. 5.2.1 Header Files All standard C library entities are declared or defined in one or more standard headers (See list in Section 5.1.3 "Chapter Organization".) To make use of a library entity in a program, write an include directive that names the relevant standard header. The contents of a standard header is included by naming it in an include directive, as in: #include <libq.h> /* include fixed point library */ The standard headers can be included in any order. Do not include a standard header within a declaration. Do not define macros that have the same names as keywords before including a standard header. A standard header never includes another standard header. (c) 2008 Microchip Technology Inc. DS51456E-page 207 16-Bit Language Tools Libraries 5.2.2 Library Files The archived library files contain all the individual object files for each library function. When linking an application, the library file must be provided as an input to the linker (using the --library or -l linker option) such that the functions used by the application may be linked into the application. A typical C application will require three library files: libc-omf.a, libm-omf.a, and libpic30-omf.a. (See Section 1.2 "OMF-Specific Libraries/Start-up Modules" for more on OMF-specific libraries.) These libraries will be included automatically if linking is performed using the compiler. 5.2.3 Function Naming Conventions Signed fixed point types are defined as follows: Qn_m where: * n is the number of data bits to the left of the radix point * m is the number of data bits to the right of the radix point Note: A sign bit is implied For convenience, short names are also defined: Exact Name # Bits Required Short Name _Q0_15 16 _Q15 _Q15_16 32 _Q16 _Q1_30 32 _Q30 Functions in the library are prefixed with the type of the return value. For example, _Q15acos returns a Q15 value equal to the arc cosine of its argument. Argument types do not always match the return type. Refer to the function prototype for a specification of its arguments. In cases where the return value is not a fixed point type, the argument type is appended to the function name. For example, function _itoaQ15 accepts a type Q15 argument. In cases where two versions of a function are provided, with the same return type but different argument types, the argument type is appended to the function name. For example: Function Name DS51456E-page 208 Return Type Argument Type _Q16reciprocalQ15 _Q16 _Q15 _Q16reciprocalQ16 _Q16 _Q16 (c) 2008 Microchip Technology Inc. Fixed Point Math Functions 5.3 <LIBQ.H> MATHEMATICAL FUNCTIONS The header file libq.h consists of macro definitions and various functions that calculate fixed point mathematical operations. 5.3.1 Q15 Functions Many functions in this section use fixed-point Q15 (0.15) format, which ranges from -215 to 215-1, or -32768 to 32767. For each function, the entire range may not be used. _Q15abs Description: The function finds the absolute value of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15abs(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the absolute value of x in Q15 format. This value ranges from 0 to 32767. _Q15acos Description: This function finds the arc cosine of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15acos(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from 17705 to 32767. Return Value: This function returns the arc cosine of x in Q15 format. This value ranges from 256 to 32767. _Q15acosByPI Description: This function finds the arc cosine of a Q15 value and then divides by PI (). Include: <libq.h> Prototype: _Q15 _Q15acosByPI(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the arc cosine of x, divided by PI, in Q15 format. This value ranges from 82 to 32767. (c) 2008 Microchip Technology Inc. DS51456E-page 209 16-Bit Language Tools Libraries _Q15add Description: The function finds the sum value of two Q15 values. This function takes care of saturation during overflow and underflow occurrences. Include: <libq.h> Prototype: _Q15 _Q15add(_Q15 x, _Q15 y); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. y a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the sum of x and y in Q15 format. This value ranges from -32768 to 32767. _Q15asin Description: This function finds the arc sine of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15asin(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -27573 to 27573. Return Value: This function returns the arc sine of x in Q15 format. This value ranges from -32768 to 32767. _Q15asinByPI Description: This function finds the arc sine of a Q15 value and then divides by PI (). Include: <libq.h> Prototype: _Q15 _Q15asinByPI(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the arc sine of x, divided by PI, in Q15 format. This value ranges from -16384 to 16303. _Q15atan DS51456E-page 210 Description: This function finds the arc tangent of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15atan(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the arc tangent of x in Q15 format. This value ranges from -25736 to 25735. (c) 2008 Microchip Technology Inc. Fixed Point Math Functions _Q15atanByPI Description: This function finds the arc tangent of a Q15 value and then divides by PI (). Include: <libq.h> Prototype: _Q15 _Q15atanByPI(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the arc tangent of x, divided by PI, in Q15 format. This value ranges from -8192 to 8192. _Q15atanYByX Description: This function finds the arc tangent of a Q15 value divided by a second Q15 value. Include: <libq.h> Prototype: _Q15 _Q15atanYByX(_Q15 x, _Q15 y); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. y a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the arc tangent of y divided by x in Q15 format. This value ranges from -25736 to 25735. _Q15atanYByXByPI Description: This function finds the arc tangent of a Q15 value divided by a second Q15 value and then divides the result by PI (). Include: <libq.h> Prototype: _Q15 _Q15atanYByXByPI(_Q15 x, _Q15 y); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. y a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the arc tangent of y divided by x, divided by PI, in Q15 format. This value ranges from -8192 to 8192. _Q15atoi Description: This function takes a string which holds the ASCII representation of decimal digits and converts it into a single Q15 number. Note: The decimal digit should not be beyond the range -32768 to 32767. Include: <libq.h> Prototype: _Q15 _Q15atoi(const char *s); Argument: s Return Value: This function returns the integer equivalent of s in Q15 format, which range is from -32768 to 32767. (c) 2008 Microchip Technology Inc. a buffer holding the ASCII values of each decimal digit. DS51456E-page 211 16-Bit Language Tools Libraries _Q15cos Description: This function finds the cosine of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15cos(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the cosine of x in Q15 format. This value ranges from 17705 to 32767. _Q15cosPI Description: This function finds the cosine of PI () times a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15cosPI(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the cosine of PI times x in Q15 format. This value ranges from -32768 to 32767. _Q15exp Description: This function finds the exponential value of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15exp(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 0. Return Value: This function returns the exponent value of x in Q15 format. This value ranges from 12055 to 32767. _Q15ftoi DS51456E-page 212 Description: This function converts a single-precision floating point value into its corresponding Q15 value. Include: <libq.h> Prototype: _Q15 _Q15ftoi(float x); Argument: x a floating point equivalent number. The corresponding floating point range is -1 to 0.99996. Return Value: This function returns a fixed point number in Q15 format. This value ranges from -32768 to 32767. (c) 2008 Microchip Technology Inc. Fixed Point Math Functions _itoaQ15 Description: This function converts the each decimal digit of a Q15 value to its representation in ASCII. For example, 1 is converted to 0x31 which is the ASCII representation of 1. Include: <libq.h> Prototype: void _itoaQ15(_Q15 x, char *s); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. s a buffer holding values in ASCII, at least 8 characters long. Return Value: None. _itofQ15 Description: This function converts a Q15 value into its corresponding floating point value. Include: <libq.h> Prototype: float _itofQ15(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns a floating point equivalent number. The corresponding floating point range is -1 to 0.99996.. _Q15log Description: This function finds the natural log of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15log(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from 12055 to 32767. Return Value: This function returns the natural log of x in Q15 format. This value ranges from -32768 to -1. _Q15log10 Description: This function finds the log (base 10) of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15log10(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from 3277 to 32767. Return Value: This function returns the log of x in Q15 format. This value ranges from -32768 to 0. (c) 2008 Microchip Technology Inc. DS51456E-page 213 16-Bit Language Tools Libraries _Q15neg Description: This function negates a Q15 value with saturation. The value is saturated in the case where the input is -32768. Include: <libq.h> Prototype: _Q15 _Q15neg(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns -x in Q15 format. This value ranges from -32768 to 32767. _Q15norm Description: This function finds the normalized value of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15norm(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the square root of x in Q15 format. This value ranges from 16384 to -32767 for a positive number and -32768 to -16384 for a negative number. _Q15power Description: This function finds the power result, given the base value and the power value in Q15 format. Include: <libq.h> Prototype: _Q15 _Q15power(_Q15 x, _Q15 y); Argument: x a fixed point number in Q15 format, which ranges from 1 to 215-1. The value of this argument ranges from 1 to 32767. y a fixed point number in Q15 format, which ranges from 1 to 215-1. The value of this argument ranges from 1 to 32767. Return Value: This function returns x to the power of y in Q15 format. This value ranges from 1 to 32767. _Q15random DS51456E-page 214 Description: This function generates a random number in the range from -32768 to 32767. The random number generation is periodic with period 65536. This function uses the _Q15randomSeed variable as a random seed value. Include: <libq.h> Prototype: _Q15 _Q15random(void); Argument: None. Return Value: This function returns a random number in Q15 format. This value ranges from -32768 to 32767. (c) 2008 Microchip Technology Inc. Fixed Point Math Functions _Q15shl Description: The function shifts a Q15 value by num bits, to the left if num is positive or to the right if num is negative. The function takes care of saturating the result, in case of underflow or overflow. Include: <libq.h> Prototype: _Q15 _Q15shl(_Q15 x, short num); Argument: x a fixed point number in Q15 format, which ranges from -215 to 15 2 -1. The value of this argument ranges from -32768 to 32767. num an integer number, which ranges from -15 to 15. Return Value: This function returns the shifted value of x in Q15 format. This value ranges from -32768 to 32767. _Q15shlNoSat Description: The function shifts a Q15 value by num bits, to the left if num is positive or to the right if num is negative. This function sets the _Q15shlSatFlag variable in case of underflow or overflow but does not take care of saturation. Include: <libq.h> Prototype: _Q15 _Q15shlNoSat(_Q15 x, short num); Argument: x a fixed point number in Q15 format, which ranges from -215 to 15-1. The value of this argument ranges from -32768 to 32767. 2 num an integer number, which ranges from -15 to 15. Return Value: This function returns the shifted value of x in Q15 format. This value ranges from -32768 to 32767. _Q15shr Description: The function shifts a Q15 value by num bits, to the right if num is positive or to the left if num is negative. The function takes care of saturating the result, in case of underflow or overflow. Include: <libq.h> Prototype: _Q15 _Q15shr(_Q15 x, short num); Argument: x a fixed point number in Q15 format, which ranges from -215 to 15-1. The value of this argument ranges from -32768 to 32767. 2 num an integer number, which ranges from -15 to 15. Return Value: This function returns the shifted value of x in Q15 format. This value ranges from -32768 to 32767. _Q15shrNoSat Description: The function shifts a Q15 value by num bits, to the right if num is positive or to the left if num is negative. This function sets the _Q15shrSatFlag variable in case of underflow or overflow but does not take care of saturation. Include: <libq.h> Prototype: _Q15 _Q15shrNoSat(_Q15 x, short num); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. num an integer number, which ranges from -15 to 15. Return Value: This function returns the shifted value of x in Q15 format. This value ranges from -32768 to 32767. (c) 2008 Microchip Technology Inc. DS51456E-page 215 16-Bit Language Tools Libraries _Q15sin Description: This function finds the sine of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15sin(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the sine of x in Q15 format. This value ranges from -27573 to 27573. _Q15sinPI Description: This function finds the sine of PI () times a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15sinPI(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the sine of PI times x in Q15 format. This value ranges from -32768 to 32767. _Q15sinSeries DS51456E-page 216 Description: Generates the sine series with the given normalizing frequency f and the given number of samples num starting from start. Stores the result in buffer buf. Include: <libq.h> Prototype: short _Q15sinSeries(_Q15 f, short start, short num, _Q15 *buf); Argument: f a fixed point number in Q15 format, which ranges from 0 to (231-1). The valid range of values for this argument is from -16384 to 16384. This argument represents the Normalizing frequency. start a fixed point number in Q16 format, which ranges from 0 to (231-1). The valid range of values for this argument is from 1 to 32767. This argument represents the Starting Sample number in the Sine Series. num a fixed point number in Q16 format, which ranges from 0 to (231-1). The valid range of values for this argument is from 1 to 32767. This argument represents the Number of Sine Samples the function is called to generate. Note: num should not be more than 16383 for dsPIC and 32767 for PIC devices. buf a pointer to the buffer where the generated sine samples would get copied into. Return Value: This function returns num, the number of generated sine samples. (c) 2008 Microchip Technology Inc. Fixed Point Math Functions _Q15sqrt Description: This function finds the square root of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15sqrt(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from 1 to 32767. Return Value: This function returns the square root of x in Q15 format. This value ranges from 1 to 32767. _Q15sub Description: The function finds the difference of two Q15 values. This function takes care of saturation during overflow and underflow occurrences. Include: <libq.h> Prototype: _Q15 _Q15sub(_Q15 x,_Q15 y); Argument: x a fixed point number in Q15 format, which ranges from -215 to 15 2 -1. The value of this argument ranges from -32768 to 32767. y a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns x minus y in Q15 format. This value ranges from -32768 to 32767. _Q15tan Description: This function finds the tangent of a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15tan(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -25736 to 25735. Return Value: This function returns the tangent of x in Q15 format. This value ranges from -32768 to 32767. _Q15tanPI Description: This function finds the tangent of PI () times a Q15 value. Include: <libq.h> Prototype: _Q15 _Q15tanPI(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the tangent of PI times x in Q15 format. This value ranges from -32768 to 32767. (c) 2008 Microchip Technology Inc. DS51456E-page 217 16-Bit Language Tools Libraries 5.3.2 Q16 Functions Many functions in this section use fixed-point Q16 (15.16) format, which ranges from -231 to 231-1, or -2147483648 to 2147483647. For each function, the entire range may not be used. _Q16acos Description: This function finds the arc cosine of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16acos(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -65566 to 65536. Return Value: This function returns the arc cosine of x in Q16 format. This value ranges from -205887 to 205887. _Q16acosByPI Description: This function finds the arc cosine of a Q16 value and then divides by PI (). Include: <libq.h> Prototype: _Q16 _Q16acosByPI(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -65536 to 65536. Return Value: This function returns the arc cosine of x, divided by PI, in Q16 format. This value ranges from -65536 to 65536. _Q16asin Description: This function finds the arc sine of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16asin(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -65566 to 65536. Return Value: This function returns the arc sine of x in Q16 format. This value ranges from -102944 to 102944. _Q16asinByPI DS51456E-page 218 Description: This function finds the arc sine of a Q16 value and then divides by PI (). Include: <libq.h> Prototype: _Q16 _Q16asinByPI(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -65536 to 65536. Return Value: This function returns the arc sine of x, divided by PI, in Q16 format. This value ranges from-65536 to 65536. (c) 2008 Microchip Technology Inc. Fixed Point Math Functions _Q16atan Description: This function finds the arc tangent of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16atan(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the arc tangent of x in Q16 format. This value ranges from -2147483648 to 2147483647. _Q16atanByPI Description: This function finds the arc tangent of a Q16 value and then divides by PI (). Include: <libq.h> Prototype: _Q16 _Q16atanByPI(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the arc tangent of x, divided by PI, in Q16 format. This value ranges from -2147483648 to 2147483647. _Q16atanYByX Description: This function finds the arc tangent of y divided by x. Include: <libq.h> Prototype: _Q16 _Q16atanYByX(_Q16 x, _Q16 y); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. This forms the x input. y a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. This forms the y input. Return Value: This function returns the arc tangent of y divided by x in Q16 format. This value ranges from -2147483648 to 2147483647. _Q16atanYByXByPI Description: This function finds the arc tangent of the 32-bit input y divided by x and then divides by PI (). Include: <libq.h> Prototype: _Q16 _Q16atanYByXByPI(_Q16 x, _Q16 y); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. This forms the x input. y a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. This forms the y input. Return Value: This function returns the arc tangent y divided by x, divided by PI, in Q16 format. This value ranges from -2147483648 to 2147483647. (c) 2008 Microchip Technology Inc. DS51456E-page 219 16-Bit Language Tools Libraries _Q16cos Description: This function finds the cosine of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16cos(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the cosine of x in Q16 format. This value ranges from -65566 to 65536. _Q16cosPI Description: This function finds the cosine of PI () times a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16cosPI(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the cosine of PI times x in Q16 format. This value ranges from -65536 to 65536. _Q16exp Description: This function finds the exponential value of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16exp(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -772244 to 681391. Return Value: This function returns the exponent value of x in Q16 format. This value ranges from 0 to 2147483647. _Q16log Description: This function finds the natural log of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16log(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from 1 to 2147483647. Return Value: This function returns the natural log of x in Q16 format. This value ranges from -726817 to 681391. _Q16log10 DS51456E-page 220 Description: This function finds the log (base 10) of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16log10(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from 1 to 2147483647. Return Value: This function returns the log of x in Q16 format. This value ranges from -315653 to 295925. (c) 2008 Microchip Technology Inc. Fixed Point Math Functions _Q16mac Description: This function multiplies the two 32-bit inputs, x and y, and accumulates the product with prod. The function takes care of saturating the result in case of underflow or overflow. Include: <libq.h> Prototype: _Q16 _Q16mac(_Q16x, _Q16 y, _Q16 prod); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. y a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. prod a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the multiplied and accumulated value prod in Q16 format. This value ranges from 0 to 2147483647. _Q16macNoSat Description: This function multiplies the two 32 bit inputs, x and y and accumulates the product with prod.This function only sets the _Q16macSatFlag variable in case of an overflow or underflow and does not take care of saturation. Include: <libq.h> Prototype: _Q16 _Q16macNoSat(_Q16 x, _Q16 y, _Q16 prod); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. y a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. prod a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the multiplied and accumulated value prod in Q16 format. This value ranges from 0 to 2147483647. _Q16neg Description: This function negates x with saturation. The value is saturated in the case where the input is -2147483648. Include: <libq.h> Prototype: _Q16 _Q16neg(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the negated value of x in Q16 format. This value ranges from -2147483648 to 2147483647. (c) 2008 Microchip Technology Inc. DS51456E-page 221 16-Bit Language Tools Libraries _Q16norm Description: This function finds the normalized value of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16norm(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the square root value of x in Q16 format. This value ranges from 1073741824 to 2147483647 for a positive number and -2147483648 to -1073741824 for a negative number. _Q16power Description: This function finds the power result, given the base value x and the power value y. Include: <libq.h> Prototype: _Q16 _Q16power(_Q16 x, _Q16 y); Argument: x a fixed point number in Q16 format. The value of this argument ranges from 0 to 2147483647. y a fixed point number in Q16 format. The value of this argument ranges from 0 to 2147483647. Return Value: This function returns the value of x to the power of y in Q16 format. This value ranges from 0 to 2147483647. _Q16random Description: This function generates pseudo random number with a period of 2147483648. This function uses the _Q16randomSeed variable as a random seed value. Include: <libq.h> Prototype: _Q16 _Q16random(void); Argument: None. Return Value: This function returns the generated random number in Q16 format. The value of this output ranges from -2147483648 to 2147483647. Remarks: RndNum(n) = (RndNum(n-1) * RAN_MULT) + RAN_INC SEED VALUE = 21845, RAN_MULT = 1664525, and RAN_INC = 1013904223. _Q16reciprocal DS51456E-page 222 Description: This function returns the reciprocal of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16reciprocal(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the reciprocal of x in Q16 format. The value of this output ranges from -2147483648 to 2147483647. (c) 2008 Microchip Technology Inc. Fixed Point Math Functions _Q16reciprocalQ15 Description: This function returns the reciprocal of a Q15 value. Since the input range lies in the -1 to +1 region, the output is always greater than the -1 or +1 region. So Q16 format is used to represent the output. Include: <libq.h> Prototype: _Q16 _Q16reciprocalQ15(_Q15 x); Argument: x a fixed point number in Q15 format, which ranges from -215 to 215-1. The value of this argument ranges from -32768 to 32767. Return Value: This function returns the reciprocal of x in Q16 format. This value ranges from -2147483648 to 2147418112. _Q16reciprocalQ16 Description: This function returns the reciprocal value of the input. Include: <libq.h> Prototype: _Q16 _Q16reciprocalQ16(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the reciprocal of x in Q16 format. The value of this output ranges from -2147483648 to 2147483647. _Q16shl Description: The function shifts the input argument x by y number of bits, to the left if y is positive or to the right if y is negative. The function takes care of saturating the result, in case of underflow or overflow. Include: <libq.h> Prototype: _Q16 _Q16shl(_Q16 x, short y); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. y an integer number, which ranges from -32 to +32. Return Value: This function returns the shifted value of x in Q16 format. This value ranges from -2147483648 to 2147483647. _Q16shlNoSat Description: The function shifts the input argument x by y number of bits, to the left if y is positive or to the right if y is negative. This function sets the _Q16shlSatFlag variable in case of underflow or overflow but does not take care of saturation. Include: <libq.h> Prototype: _Q16 _Q16shlNoSat(_Q16 x, short y); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. y an integer number, which ranges from -32 to +32. Return Value: This function returns the shifted value of x in Q16 format. This value ranges from -2147483648 to 2147483647. (c) 2008 Microchip Technology Inc. DS51456E-page 223 16-Bit Language Tools Libraries _Q16shr Description: The function shifts the input argument x by y number of bits, to the right if y is positive or to the left if y is negative. The function takes care of saturating the result, in case of underflow or overflow. Include: <libq.h> Prototype: _Q16 _Q16shr(_Q16 x, short y); Argument: x a fixed point number in Q16 format. The value of this argument ranges from-2147483648 to 2147483647. y an integer number, which ranges from -32 to +32. Return Value: This function returns the shifted value of x in Q16 format. This value ranges from -2147483648 to 2147483647. _Q16shrNoSat Description: The function shifts the input argument x by y number of bits, to the right if y is positive or to the left if y is negative. This function sets the _Q16shrSatFlag variable in case of underflow or overflow but does not take care of saturation. Include: <libq.h> Prototype: _Q16 _Q16shrNoSat(_Q16 x, short y); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. y an integer number, which ranges from -32 to +32. Return Value: This function returns the shifted value of x in Q16 format. This value ranges from -2147483648 to 2147483647. _Q16sin Description: This function finds the sine of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16sin(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the sine of x in Q16 format. This value ranges from -65566 to 65536. _Q16sinPI DS51456E-page 224 Description: This function finds the sine of PI () times a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16sinPI(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the sine of PI times x in Q16 format. This value ranges from -65536 to 65536. (c) 2008 Microchip Technology Inc. Fixed Point Math Functions _Q16sinSeries Description: Generates the sine series with the given normalizing frequency f and the given number of samples num starting from start. Stores the result in buffer buf. Include: <libq.h> Prototype: short _Q16sinSeries(_Q16 f, short start, short num, _Q16 *buf); Argument: f a fixed point number in Q16 format, which ranges from 0 to (231-1). The valid range of values for this argument is from -32768 to 32768. This argument represents the Normalizing frequency. start a fixed point number in Q16 format, which ranges from 0 to (231-1). The valid range of values for this argument is from 1 to 32767. This argument represents the Starting Sample number in the Sine Series. num a fixed point number in Q16 format, which ranges from 0 to (231-1). The valid range of values for this argument is from 1 to 32767. This argument represents the Number of Sine Samples the function is called to generate. Note: num should not be more than 16383 for dsPIC and 32767 for PIC devices. buf a pointer to the buffer where the generated sine samples would get copied into. Return Value: This function returns num, the number of generated sine samples. _Q16tan Description: This function finds the tangent of a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16tan(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the tangent of x in Q16 format. This value ranges from-2147483648 to 2147483647. _Q16tanPI Description: This function finds the tangent of PI () times a Q16 value. Include: <libq.h> Prototype: _Q16 _Q16tanPI(_Q16 x); Argument: x a fixed point number in Q16 format. The value of this argument ranges from -2147483648 to 2147483647. Return Value: This function returns the tangent of PI times x in Q16 format. This value ranges from -2147483648 to 2147483647. (c) 2008 Microchip Technology Inc. DS51456E-page 225 16-Bit Language Tools Libraries NOTES: DS51456E-page 226 (c) 2008 Microchip Technology Inc. 16-BIT LANGUAGE TOOLS LIBRARIES Appendix A. ASCII Character Set TABLE A-1: ASCII CHARACTER SET Most Significant Character Least Significant Character (c) 2008 Microchip Technology Inc. Hex 0 1 2 3 4 5 6 7 0 NUL DLE Space 0 @ P ` p 1 SOH DC1 ! 1 A Q a q 2 STX DC2 " 2 B R b r 3 ETX DC3 # 3 C S c s 4 EOT DC4 $ 4 D T d t 5 ENQ NAK % 5 E U e u 6 ACK SYN & 6 F V f v 7 Bell ETB ' 7 G W g w 8 BS CAN ( 8 H X h x 9 HT EM ) 9 I Y i y A LF SUB * : J Z j z B VT ESC + ; K [ k { C FF FS , < L \ l | D CR GS - = M ] m } E SO RS . > N ^ n ~ F SI US / ? O _ o DEL DS51456E-page 227 16-Bit Language Tools Libraries NOTES: DS51456E-page 228 (c) 2008 Microchip Technology Inc. 16-BIT LANGUAGE TOOLS LIBRARIES Index Symbols ^, Caret..................................................................... 80 __attach_input_file ................................................. 197 __C30_UART......................................................... 198 __close_input_file .................................................. 197 __delay32 .............................................................. 198 __FILE__ ................................................................. 13 __LINE__ ................................................................. 13 _erase_eedata ....................................................... 199 _erase_eedata_all ................................................. 199 _erase_flash .......................................................... 201 _exit ....................................................................... 191 _init_prog_address ................................................ 204 _IOFBF .........................................................46, 81, 82 _IOLBF................................................................46, 82 _IONBF .........................................................46, 81, 82 _itoaQ15 ................................................................ 213 _itofQ15 ................................................................. 213 _MathError ............................................................... 37 _memcpy_p2d16 ................................................... 203 _memcpy_p2d24 ................................................... 203 _NSETJMP .............................................................. 32 _Q15abs ................................................................ 209 _Q15acos............................................................... 209 _Q15acosByPI ....................................................... 209 _Q15add ................................................................ 210 _Q15asin................................................................ 210 _Q15asinByPI ........................................................ 210 _Q15atan ............................................................... 210 _Q15atanByPI........................................................ 211 _Q15atanYByX ...................................................... 211 _Q15atanYByXByPI............................................... 211 _Q15atoi ................................................................ 211 _Q15cos................................................................. 212 _Q15cosPI ............................................................. 212 _Q15exp ................................................................ 212 _Q15ftoi ................................................................. 212 _Q15log ................................................................. 213 _Q15log10 ............................................................. 213 _Q15neg ................................................................ 214 _Q15norm .............................................................. 214 _Q15power ............................................................ 214 _Q15random .......................................................... 214 _Q15shl.................................................................. 215 _Q15shlNoSat........................................................ 215 _Q15shr ................................................................. 215 _Q15shrNoSat ....................................................... 215 _Q15sin.................................................................. 216 _Q15sinPI .............................................................. 216 _Q15sinSeries ....................................................... 216 _Q15sqrt ................................................................ 217 (c) 2008 Microchip Technology Inc. _Q15sub................................................................. 217 _Q15tan ................................................................. 217 _Q15tanPI .............................................................. 217 _Q16acos............................................................... 218 _Q16acosByPI ....................................................... 218 _Q16asin................................................................ 218 _Q16asinByPI ........................................................ 218 _Q16atan ............................................................... 219 _Q16atanByPI........................................................ 219 _Q16atanYByX ...................................................... 219 _Q16atanYByXByPI............................................... 219 _Q16cos................................................................. 220 _Q16cosPI ............................................................. 220 _Q16exp................................................................. 220 _Q16log.................................................................. 220 _Q16log10.............................................................. 220 _Q16mac (Continued)............................................ 221 _Q16macNoSat...................................................... 221 _Q16neg ................................................................ 221 _Q16norm .............................................................. 222 _Q16power............................................................. 222 _Q16random .......................................................... 222 _Q16reciprocal....................................................... 222 _Q16reciprocalQ15 ................................................ 223 _Q16reciprocalQ16 ................................................ 223 _Q16shl.................................................................. 223 _Q16shlNoSat........................................................ 223 _Q16shr ................................................................. 224 _Q16shrNoSat ....................................................... 224 _Q16sin.................................................................. 224 _Q16sinPI .............................................................. 224 _Q16sinSeries........................................................ 225 _Q16tan ................................................................. 225 _Q16tanPI .............................................................. 225 _strncpy_p2d16...................................................... 204 _strncpy_p2d24...................................................... 204 _VERBOSE_DEBUGGING...................................... 13 _wait_eedata.......................................................... 200 _write_eedata_row................................................. 200 _write_eedata_word............................................... 200 _write_flash_word16 .............................................. 202 _write_flash_word24 .............................................. 202 _write_flash16 ........................................................ 201 _write_flash24 ........................................................ 201 -, Dash...................................................................... 80 \f, Form Feed............................................................ 19 \n, Newline .............................19, 43, 55, 60, 71, 72, 76 \r, Carriage Return ................................................... 19 \t, Horizontal Tab...................................................... 19 \v, Vertical Tab ......................................................... 19 #if ............................................................................. 29 DS51456E-page 229 16-Bit Language Tools Libraries #include .............................................12, 145, 190, 207 %, Percent.............................................74, 79, 80, 143 Numerics 0x ........................................................20, 73, 111, 112 A Abnormal Termination Signal ................................... 34 abort ................................................................... 13, 91 abs ........................................................................... 92 Absolute Value Double Floating Point...................................... 161 Integer ............................................................... 92 Long Integer .................................................... 102 Single Floating Point ....................................... 161 Absolute Value Function abs .................................................................... 92 fabs ................................................................. 161 fabsf ................................................................ 161 labs ................................................................. 102 Access Mode Binary ................................................................ 56 Text ................................................................... 56 acos........................................................................ 147 acosf....................................................................... 148 Allocate Memory..................................................... 104 calloc ................................................................. 98 Free................................................................. 101 realloc ............................................................. 107 Alphabetic Character Defined.............................................................. 14 Test for .............................................................. 14 Alphanumeric Character Defined.............................................................. 14 Test for .............................................................. 14 AM/PM ................................................................... 143 Append ........................................................... 120, 126 arccosine Double Floating Point...................................... 147 Single Floating Point ....................................... 148 arcsine Double Floating Point...................................... 149 Single Floating Point ....................................... 149 arctangent Double Floating Point...................................... 150 Single Floating Point ....................................... 151 arctangent of y/x Double Floating Point...................................... 151 Single Floating Point ....................................... 153 Argument List ..........................................39, 87, 88, 89 Arithmetic Error Message......................................... 34 ASCII Character Set............................................... 227 asctime ................................................................... 138 asin......................................................................... 149 asinf........................................................................ 149 assert ....................................................................... 13 assert.h .................................................................... 13 Assignment Suppression.......................................... 79 Asterisk .............................................................. 73, 79 atan ........................................................................ 150 atan2 ...................................................................... 151 DS51456E-page 230 atan2f ..................................................................... 153 atanf ....................................................................... 151 atexit................................................................. 92, 100 atof ........................................................................... 94 atoi............................................................................ 95 atol............................................................................ 95 attach_input_file ..................................................... 197 B Base ............................................................... 111, 112 10 ..................................... 25, 26, 27, 28, 173, 174 2 ........................................................................ 27 e .............................................................. 172, 175 FLT_RADIX.......................... 24, 25, 26, 27, 28, 29 Binary Base .................................................................. 27 Mode ........................................................... 56, 84 Search............................................................... 96 Streams............................................................. 43 Bitfields..................................................................... 42 brk .................................................................. 191, 194 bsearch..................................................................... 96 Buffer Size.......................................................... 46, 82 Buffering Modes ....................................................... 82 Buffering, See File Buffering BUFSIZ............................................................... 46, 81 Built-in Functions........................................................ 9 C C Locale ............................................................. 14, 31 C30_UART ............................................................. 198 Calendar Time......................... 137, 139, 140, 142, 144 calloc ................................................................ 98, 101 Caret (^).................................................................... 80 Carriage Return........................................................ 19 ceil .......................................................................... 154 ceilf ......................................................................... 155 ceiling Double Floating Point...................................... 154 Single Floating Point ....................................... 155 char Maximum Value ................................................ 29 Minimum Value ................................................. 29 Number of Bits .................................................. 29 CHAR_BIT................................................................ 29 CHAR_MAX ............................................................. 29 CHAR_MIN............................................................... 29 Character Array ........................................................ 80 Character Case Mapping Lower Case Alphabetic Character .................... 21 Upper Case Alphabetic Character .................... 22 Character Case Mapping Functions tolower............................................................... 21 toupper .............................................................. 22 Character Handling, See ctype.h Character Input/Output Functions fgetc .................................................................. 53 fgets .................................................................. 55 fputc .................................................................. 59 fputs .................................................................. 59 getc ................................................................... 70 (c) 2008 Microchip Technology Inc. Index getchar .............................................................. 71 gets ................................................................... 71 putc ................................................................... 75 putchar .............................................................. 76 puts ................................................................... 76 ungetc ............................................................... 85 Character Testing Alphabetic Character ........................................ 14 Alphanumeric Character ................................... 14 Control Character ............................................. 15 Decimal Digit..................................................... 16 Graphical Character.......................................... 16 Hexadecimal Digit ............................................. 20 Lower Case Alphabetic Character .................... 17 Printable Character ........................................... 18 Punctuation Character ...................................... 18 Upper Case Alphabetic Character .................... 20 White-Space Character .................................... 19 Character Testing Functions isalnum ............................................................. 14 isalpha .............................................................. 14 iscntrl ................................................................ 15 isdigit................................................................. 16 isgraph .............................................................. 16 islower............................................................... 17 isprint ................................................................ 18 ispunct .............................................................. 18 isspace.............................................................. 19 isupper .............................................................. 20 isxdigit ............................................................... 20 Characters Alphabetic ......................................................... 14 Alphanumeric .................................................... 14 Control .............................................................. 15 Convert to Lower Case Alphabetic ................... 21 Convert to Upper Case Alphabetic ................... 22 Decimal Digit..................................................... 16 Graphical .......................................................... 16 Hexadecimal Digit ............................................. 20 Lower Case Alphabetic ..................................... 17 Printable............................................................ 18 Punctuation....................................................... 18 Upper Case Alphabetic ..................................... 20 White-Space ..................................................... 19 Classifying Characters ............................................. 14 clearerr ..................................................................... 49 Clearing Error Indicator ............................................ 49 clock ....................................................................... 138 clock_t .............................................................137, 138 CLOCKS_PER_SEC ............................................. 137 close....................................................................... 192 close_input_file ...................................................... 197 COFF ......................................................................... 8 Common Definitions, See stddef.h Compare Strings .................................................... 122 Comparison Function ........................................96, 106 Comparison Functions memcmp ......................................................... 115 strcmp ............................................................. 122 strcoll .............................................................. 123 strncmp ........................................................... 128 (c) 2008 Microchip Technology Inc. strxfrm ............................................................. 136 Compiler Options -fno-short-double............................................... 44 -msmart-io......................................................... 43 Concatenation Functions strcat ............................................................... 120 strncat ............................................................. 126 Control Character Defined.............................................................. 15 Test for.............................................................. 15 Control Transfers ..................................................... 32 Conversion ....................................................73, 79, 83 Convert Character to Multibyte Character .................... 113 Multibyte Character to Wide Character........... 105 Multibyte String to Wide Character String....... 105 String to Double Floating Point ................. 94, 109 String to Integer ................................................ 95 String to Long Integer ............................... 95, 111 String to Unsigned Long Integer ..................... 112 To Lower Case Alphabetic Character ............... 21 To Upper Case Alphabetic Character ............... 22 Wide Character String to Multibyte String....... 113 Copying Functions memcpy .......................................................... 117 memmove ....................................................... 118 memset ........................................................... 119 strcpy .............................................................. 123 strncpy ............................................................ 129 cos.......................................................................... 155 cosf......................................................................... 156 cosh........................................................................ 157 coshf....................................................................... 158 cosine Double Floating Point...................................... 155 Single Floating Point ....................................... 156 crt0, crt1 ..................................................................... 8 ctime....................................................................... 139 ctype.h...................................................................... 14 isalnum.............................................................. 14 iscntrl................................................................. 15 isdigit................................................................. 16 isgraph .............................................................. 16 islapha............................................................... 14 islower............................................................... 17 ispring ............................................................... 18 ispunct............................................................... 18 isspace.............................................................. 19 isupper .............................................................. 20 isxdigit ............................................................... 20 tolower .............................................................. 21 toupper.............................................................. 22 Current Argument..................................................... 39 Customer Notification Service.................................... 4 Customer Support ...................................................... 5 Customized Function ............................................. 101 D Dash (-) .................................................................... 80 Date and Time........................................................ 142 Date and Time Functions, See time.h DS51456E-page 231 16-Bit Language Tools Libraries Day of the Month .....................................137, 138, 142 Day of the Week......................................137, 138, 142 Day of the Year .............................................. 137, 143 Daylight Savings Time.............................137, 140, 141 DBL_DIG .................................................................. 24 DBL_EPSILON......................................................... 24 DBL_MANT_DIG...................................................... 24 DBL_MAX ................................................................ 24 DBL_MAX_10_EXP ................................................. 25 DBL_MAX_EXP ....................................................... 25 DBL_MIN.................................................................. 25 DBL_MIN_10_EXP .................................................. 25 DBL_MIN_EXP ........................................................ 26 Deallocate Memory ........................................ 101, 107 Debugging Logic Errors............................................ 13 Decimal ...............................................74, 80, 111, 112 Decimal Digit Defined.............................................................. 16 Number Of .............................................24, 26, 27 Test for .............................................................. 16 Decimal Point ........................................................... 73 Default Handler ........................................................ 33 delay32................................................................... 198 Diagnostics, See assert.h difftime.................................................................... 140 Digit, Decimal, See Decimal Digit Digit, Hexadecimal, See Hexadecimal Digit Direct Input/Output Functions fread .................................................................. 60 fwrite ................................................................. 68 div....................................................................... 90, 98 div_t.......................................................................... 90 Divide Integer ............................................................... 98 Long Integer .................................................... 103 Divide by Zero ...............................................34, 37, 98 Documentation Conventions ........................................................ 2 Layout ................................................................. 1 Domain Error .....23, 147, 148, 149, 151, 153, 155, 156, 163, 165, 172, 173, 174, 175, 180, 181, 184, 185, 186 dot ............................................................................ 73 Double Precision Floating Point Machine Epsilon................................................ 24 Maximum Exponent (base 10) .......................... 25 Maximum Exponent (base 2) ............................ 25 Maximum Value ................................................ 24 Minimum Exponent (base 10) ........................... 25 Minimum Exponent (base 2) ............................. 26 Minimum Value ................................................. 25 Number of Binary Digits .................................... 24 Number of Decimal Digits ................................. 24 double Type ............................................................. 44 Dream Function........................................................ 73 DWARF ...................................................................... 8 E EDOM ...................................................................... 23 edom ...................................................................... 147 ELF............................................................................. 8 Ellipses (...) ........................................................ 39, 80 DS51456E-page 232 Empty Binary File ..................................................... 56 Empty Text File ........................................................ 56 End Of File ............................................................... 46 Indicator ............................................................ 43 Seek .................................................................. 64 Test For............................................................. 51 Environment Function getenv ............................................................. 101 Environment Variable ............................................. 196 EOF .......................................................................... 46 ERANGE .................................................................. 23 erange .................................................................... 147 erase_eedata ......................................................... 199 erase_eedata_all.................................................... 199 erase_flash............................................................. 201 errno ................................................................. 23, 147 errno.h ...................................................... 23, 147, 193 EDOM ............................................................... 23 ERANGE ........................................................... 23 errno.................................................................. 23 Error Codes ...................................................... 23, 125 Error Conditions ..................................................... 147 Error Handler ............................................................ 98 Error Handling Functions clearerr .............................................................. 49 feof .................................................................... 51 ferror.................................................................. 52 perror................................................................. 72 Error Indicator........................................................... 43 Error Indicators Clearing....................................................... 49, 78 End Of File .................................................. 49, 55 Error ............................................................ 49, 55 Test For............................................................. 52 Error Signal .............................................................. 33 Errors, See errno.h Errors, Testing For ................................................... 23 Exception Error......................................................... 98 exit................................................. 84, 90, 92, 100, 191 EXIT_FAILURE ........................................................ 90 EXIT_SUCCESS ...................................................... 90 exp.......................................................................... 159 expf......................................................................... 160 Exponential and Logarithmic Functions exp .................................................................. 159 expf ................................................................. 160 frexp ................................................................ 167 frexpf ............................................................... 168 ldexp................................................................ 169 ldexpf............................................................... 170 log ................................................................... 172 log10 ............................................................... 173 log10f .............................................................. 174 logf .................................................................. 175 modf ................................................................ 176 modff ............................................................... 177 Exponential Function Double Floating Point...................................... 159 Single Floating Point ....................................... 160 (c) 2008 Microchip Technology Inc. Index F fabs ........................................................................ 161 fabsf ....................................................................... 161 fclose.................................................................50, 192 feof ......................................................................49, 51 ferror ...................................................................49, 52 fflush .................................................................53, 195 fgetc ..................................................................53, 194 fgetpos ..............................................................54, 193 fgets ..................................................................55, 194 Field Width ............................................................... 73 FILE ..............................................................13, 43, 45 File Access Functions fclose ................................................................ 50 fflush ................................................................. 53 fopen................................................................. 56 freopen.............................................................. 62 setbuf ................................................................ 81 setvbuf .............................................................. 82 File Access Modes ..............................................43, 56 File Buffering Fully Buffered...............................................43, 46 Line Buffered ...............................................43, 46 Unbuffered ...................................................43, 46 File Operations Remove ............................................................ 77 Rename ............................................................ 77 File Positioning Functions fgetpos .............................................................. 54 fseek ................................................................. 64 fsetpos .............................................................. 65 ftell .................................................................... 67 rewind ............................................................... 78 FILENAME_MAX ..................................................... 46 File-Position Indicator ...... 43, 45, 53, 54, 59, 60, 65, 68 Files, Maximum Number Open ................................ 46 Fixed Point Math Library ........................................ 207 flags ......................................................................... 73 float.h ....................................................................... 24 DBL_DIG .......................................................... 24 DBL_EPSILON ................................................. 24 DBL_MANT_DIG .............................................. 24 DBL_MAX ......................................................... 24 DBL_MAX_10_EXP .......................................... 25 DBL_MAX_EXP ................................................ 25 DBL_MIN .......................................................... 25 DBL_MIN_10_EXP ........................................... 25 DBL_MIN_EXP ................................................. 26 FLT_DIG ........................................................... 26 FLT_EPSILON .................................................. 26 FLT_MANT_DIG ............................................... 26 FLT_MAX.......................................................... 26 FLT_MAX_10_EXP .......................................... 26 FLT_MAX_EXP ................................................ 27 FLT_MIN ........................................................... 27 FLT_MIN_10_EXP............................................ 27 FLT_MIN_EXP.................................................. 27 FLT_RADIX ...................................................... 27 FLT_ROUNDS .................................................. 27 LDBL_DIG ........................................................ 27 (c) 2008 Microchip Technology Inc. LDBL_EPSILON ............................................... 28 LDBL_MANT_DIG ............................................ 28 LDBL_MAX ....................................................... 28 LDBL_MAX_10_EXP ........................................ 28 LDBL_MAX_EXP .............................................. 28 LDBL_MIN ........................................................ 28 LDBL_MIN_10_EXP ......................................... 28 LDBL_MIN_EXP ............................................... 29 Floating Point Limits................................................................. 24 No Conversion .................................................. 43 Types, Properties Of ......................................... 24 Floating Point, See float.h Floating-Point Error Signal ....................................... 34 floor ........................................................................ 162 Double Floating Point...................................... 162 Single Floating Point ....................................... 162 floorf ....................................................................... 162 FLT_DIG .................................................................. 26 FLT_EPSILON ......................................................... 26 FLT_MANT_DIG ...................................................... 26 FLT_MAX ................................................................. 26 FLT_MAX_10_EXP.................................................. 26 FLT_MAX_EXP........................................................ 27 FLT_MIN .................................................................. 27 FLT_MIN_10_EXP ................................................... 27 FLT_MIN_EXP ......................................................... 27 FLT_RADIX.............................................................. 27 FLT_RADIX Digit Number Of .............................................24, 26, 28 FLT_ROUNDS ......................................................... 27 Flush ................................................................ 53, 100 fmod ....................................................................... 163 fmodf ...................................................................... 165 -fno-short-double..................................... 24, 25, 26, 44 fopen ..................................................... 43, 56, 82, 193 FOPEN_MAX ........................................................... 46 Form Feed................................................................ 19 Format Specifiers ............................................... 73, 79 Formatted I/O Routines............................................ 43 Formatted Input/Output Functions fprintf ................................................................. 58 fscanf ................................................................ 62 printf .................................................................. 73 scanf ................................................................. 79 sprintf ................................................................ 83 sscanf................................................................ 83 vfprintf ............................................................... 87 vprintf ................................................................ 88 vsprintf .............................................................. 89 Formatted Text Printing.............................................................. 83 Scanning ........................................................... 83 fpos_t ....................................................................... 45 fprintf .................................................................. 43, 58 fputc ......................................................................... 59 fputs ......................................................................... 59 fraction and exponent function Double Floating Point...................................... 167 Single Floating Point ....................................... 168 DS51456E-page 233 16-Bit Language Tools Libraries Fraction Digits .......................................................... 73 fread ................................................................. 60, 194 free ......................................................................... 101 Free Memory .......................................................... 101 freopen ........................................................43, 62, 193 frexp ....................................................................... 167 frexpf ...................................................................... 168 fscanf.................................................................. 43, 62 fseek............................................................64, 85, 193 fsetpos.........................................................65, 85, 193 ftell.................................................................... 67, 193 Full Buffering ...................................................... 81, 82 Fully Buffered ..................................................... 43, 46 fwrite......................................................................... 68 G getc .......................................................................... 70 getchar ..................................................................... 71 getenv ............................................................ 101, 196 gets .................................................................. 71, 194 GMT ....................................................................... 140 gmtime ........................................................... 140, 141 Graphical Character Defined.............................................................. 16 Test for .............................................................. 16 Greenwich Mean Time ........................................... 140 H h modifier ........................................................... 74, 79 Handler Default............................................................... 33 Error .................................................................. 98 Interrupt............................................................. 37 Nested............................................................... 32 Signal .......................................................... 33, 38 Signal Type ....................................................... 33 Handling Interrupt Signal.................................................. 38 Header Files assert.h ............................................................. 13 ctype.h .............................................................. 14 errno.h................................................23, 147, 193 float.h ................................................................ 24 libq.h ............................................................... 209 limits.h ............................................................... 29 locale.h.............................................................. 31 math.h ............................................................. 147 setjmp.h ............................................................ 32 signal.h.............................................................. 33 stdarg.h ............................................................. 39 stddef.h ............................................................. 41 stdio.h ....................................................... 43, 196 stdlib.h....................................................... 90, 196 string.h ............................................................ 114 time.h ...................................................... 137, 197 Heap....................................................................... 192 Hexadecimal .......................................74, 80, 111, 112 Hexadecimal Conversion ......................................... 73 Hexadecimal Digit Defined.............................................................. 20 Test for .............................................................. 20 DS51456E-page 234 Horizontal Tab .......................................................... 19 Hour........................................................ 137, 138, 142 HUGE_VAL ............................................................ 147 Hyperbolic Cosine Double Floating Point...................................... 157 Single Floating Point ....................................... 158 Hyperbolic Functions cosh................................................................. 157 coshf................................................................ 158 sinh.................................................................. 182 sinhf................................................................. 183 tanh ................................................................. 187 tanhf ................................................................ 188 Hyperbolic Sine Double Floating Point...................................... 182 Single Floating Point ....................................... 183 Hyperbolic Tangent Double Floating Point...................................... 187 hyperbolic tangent Single Floating Point ....................................... 188 I Ignore Signal ............................................................ 33 Illegal Instruction Signal ........................................... 35 Implementation-Defined Limits, See limits.h Indicator End Of File .................................................. 43, 46 Error ............................................................ 43, 52 File Position.................... 43, 53, 54, 59, 60, 65, 68 Infinity ..................................................................... 147 init_prog_address................................................... 204 Input and Output, See stdio.h Input Formats ........................................................... 43 Instruction Cycles ................................... 140, 141, 144 int Maximum Value ................................................ 29 Minimum Value ................................................. 29 INT_MAX.................................................................. 29 INT_MIN ................................................................... 29 Integer Limits............................................................ 29 Internal Error Message........................................... 125 Internet Address, Microchip........................................ 4 Interrupt Handler ...................................................... 37 Interrupt Signal ......................................................... 35 Interrupt Signal Handling.......................................... 38 Interruption Message................................................ 35 Invalid Executable Code Message ........................... 35 Invalid Storage Request Message ........................... 36 Inverse Cosine, See arccosine Inverse Sine, See arcsine Inverse Tangent, See arctangent IOFBF........................................................... 46, 81, 82 IOLBF ................................................................. 46, 82 IONBF .......................................................... 46, 81, 82 isalnum ..................................................................... 14 iscntrl ........................................................................ 15 isdigit ........................................................................ 16 isgraph...................................................................... 16 islapha ...................................................................... 14 islower ...................................................................... 17 isprint........................................................................ 18 (c) 2008 Microchip Technology Inc. Index ispunct...................................................................... 18 isspace ..................................................................... 19 isupper ..................................................................... 20 isxdigit ...................................................................... 20 J jmp_buf .................................................................... 32 Justify ....................................................................... 73 L L modifier ............................................................74, 79 l modifier .............................................................74, 79 L_tmpnam ...........................................................47, 85 labs ........................................................................ 102 LC_ALL .................................................................... 31 LC_COLLATE .......................................................... 31 LC_CTYPE .............................................................. 31 LC_MONETARY ...................................................... 31 LC_NUMERIC.......................................................... 31 LC_TIME .................................................................. 31 lconv, struct .............................................................. 31 LDBL_DIG................................................................ 27 LDBL_EPSILON ...................................................... 28 LDBL_MANT_DIG ................................................... 28 LDBL_MAX .............................................................. 28 LDBL_MAX_10_EXP ............................................... 28 LDBL_MAX_EXP ..................................................... 28 LDBL_MIN ............................................................... 28 LDBL_MIN_10_EXP ................................................ 28 LDBL_MIN_EXP ...................................................... 29 ldexp ...................................................................... 169 ldexpf ..................................................................... 170 ldiv.....................................................................90, 103 ldiv_t......................................................................... 90 Leap Second...................................................137, 143 Left Justify ................................................................ 73 libc.............................................................................. 9 libdsp.......................................................................... 8 libm ............................................................................ 9 libp ............................................................................. 8 libpic30 ....................................................................... 9 libpic30, Rebuilding................................................ 190 libq.h ...................................................................... 209 Libraries Fixed Point Math ............................................. 207 Math................................................................ 145 Standard C........................................................ 11 Standard C Math............................................. 147 Support ........................................................... 189 Limits Floating Point .................................................... 24 Integer............................................................... 29 limits.h ...................................................................... 29 CHAR_BITS...................................................... 29 CHAR_MAX ...................................................... 29 CHAR_MIN ....................................................... 29 INT_MAX. ......................................................... 29 INT_MIN. .......................................................... 29 LLONG_MAX .................................................... 29 LLONG_MIN ..................................................... 30 LONG_MAX. ..................................................... 30 (c) 2008 Microchip Technology Inc. LONG_MIN. ...................................................... 30 MB_LEN_MAX.................................................. 30 SCHAR_MAX.................................................... 30 SCHAR_MIN..................................................... 30 SHRT_MAX. ..................................................... 30 SHRT_MIN........................................................ 30 UCHAR_MAX ................................................... 31 UINT_MAX........................................................ 31 ULLONG_MAX ................................................. 31 ULONG_MAX. .................................................. 31 USHRT_MAX.................................................... 31 LINE ......................................................................... 13 Line Buffered...................................................... 43, 46 Line Buffering ........................................................... 82 ll modifier............................................................ 74, 79 LLONG_MAX ........................................................... 29 LLONG_MIN ............................................................ 30 Load Exponent Function Double Floating Point...................................... 169 Single Floating Point ....................................... 170 Local Time...............................................139, 141, 142 Locale, C ............................................................ 14, 31 Locale, Other............................................................ 31 locale.h..................................................................... 31 localeconv ................................................................ 31 Localization, See locale.h localtime ..................................................139, 140, 141 Locate Character.................................................... 121 log .......................................................................... 172 log10 ...................................................................... 173 log10f ..................................................................... 174 Logarithm Function Double Floating Point...................................... 173 Single Floating Point ....................................... 174 Logarithm Function, Natural Double Floating Point...................................... 172 Single Floating Point ....................................... 175 logf ......................................................................... 175 Logic Errors, Debugging .......................................... 13 Long Double Precision Floating Point Machine Epsilon................................................ 28 Maximum Exponent (base 10) .......................... 28 Maximum Exponent (base 2) ............................ 28 Maximum Value ................................................ 28 Minimum Exponent (base 10) ........................... 28 Minimum Exponent (base 2) ............................. 29 Minimum Value ................................................. 28 Number of Binary Digits .................................... 28 Number of Decimal Digits ................................. 27 long double Type...................................................... 44 long int Maximum Value ................................................ 30 Minimum Value ................................................. 30 long long int Maximum Value ................................................ 29 Minimum Value ................................................. 30 long long unsigned int Maximum Value ................................................ 31 long unsigned int Maximum Value ................................................ 31 DS51456E-page 235 16-Bit Language Tools Libraries LONG_MAX ............................................................. 30 LONG_MIN .............................................................. 30 longjmp..................................................................... 32 Lower Case Alphabetic Character Convert To ........................................................ 21 Defined.............................................................. 17 Test for .............................................................. 17 lseek ....................................................................... 193 M Machine Epsilon Double Floating Point........................................ 24 Long Double Floating Point............................... 28 Single Floating Point ......................................... 26 Magnitude ............... 147, 159, 160, 163, 165, 182, 183 malloc ..............................................101, 104, 191, 194 Mapping Characters ................................................. 14 Math Exception Error................................................ 98 Math Library ........................................................... 145 math.h .................................................................... 147 acos. ............................................................... 147 acosf. .............................................................. 148 asin. ................................................................ 149 asinf ................................................................ 149 atan. ................................................................ 150 atan2. .............................................................. 151 atan2f. ............................................................. 153 atanf. ............................................................... 151 ceil................................................................... 154 ceilf.................................................................. 155 cos .................................................................. 155 cosf ................................................................. 156 cosh ................................................................ 157 coshf ............................................................... 158 exp .................................................................. 159 expf ................................................................. 160 fabs ................................................................. 161 fabsf ................................................................ 161 floor ................................................................. 162 floorf ................................................................ 162 fmod ................................................................ 163 fmodf ............................................................... 165 frexp ................................................................ 167 frexpf ............................................................... 168 HUGE_VAL. .................................................... 147 ldexp ............................................................... 169 ldexpf .............................................................. 170 log ................................................................... 172 log10 ............................................................... 173 log10f .............................................................. 174 logf .................................................................. 175 modf ................................................................ 176 modff ............................................................... 177 pow ................................................................. 178 powf ................................................................ 179 sin ................................................................... 180 sinf .................................................................. 181 sinh ................................................................. 182 sinhf ................................................................ 183 sqrt .................................................................. 184 sqrtf ................................................................. 185 DS51456E-page 236 tan ................................................................... 186 tanf .................................................................. 186 tanh ................................................................. 187 tanhf ................................................................ 188 Mathematical Functions, See libq.h Mathematical Functions, See math.h MathError ................................................................. 37 Maximum Multibyte Character ........................................... 91 Maximum Value Double Floating-Point Exponent (base 10) ....... 25 Double Floating-Point Exponent (base 2) ......... 25 Long Double Floating-Point Exponent (base 10)............................................. 28 Long Double Floating-Point Exponent (base 2)............................................... 28 Multibyte Character ........................................... 30 rand ................................................................... 91 Single Floating-Point Exponent (base 10)......... 26 Single Floating-Point Exponent (base 2)........... 27 Type char .......................................................... 29 Type Double...................................................... 24 Type int ............................................................. 29 Type Long Double............................................. 28 Type long int...................................................... 30 Type long long int.............................................. 29 Type long long unsigned int .............................. 31 Type long unsigned int ...................................... 31 Type short int .................................................... 30 Type signed char............................................... 30 Type Single ....................................................... 26 Type unsigned char........................................... 31 Type unsigned int.............................................. 31 Type unsigned short int..................................... 31 MB_CUR_MAX ........................................................ 91 MB_LEN_MAX ......................................................... 30 mblen...................................................................... 105 mbstowcs ............................................................... 105 mbtowc ................................................................... 105 memchr .................................................................. 114 memcmp................................................................. 115 memcpy.................................................................. 117 memcpy_p2d16...................................................... 203 memcpy_p2d24...................................................... 203 memmove............................................................... 118 Memory Allocate ..................................................... 98, 104 Deallocate ....................................................... 101 Free................................................................. 101 Reallocate ....................................................... 107 memset................................................................... 119 Message Arithmetic Error ................................................. 34 Interrupt............................................................. 35 Invalid Executable Code ................................... 35 Invalid Storage Request.................................... 36 Termination Request......................................... 36 Minimum Value Double Floating-Point Exponent (base 10) ....... 25 Double Floating-Point Exponent (base 2) ......... 26 (c) 2008 Microchip Technology Inc. Index Long Double Floating-Point Exponent (base 10) ............................................ 28 Long Double Floating-Point Exponent (base 2) .............................................. 29 Single Floating-Point Exponent (base 10) ........ 27 Single Floating-Point Exponent (base 2) .......... 27 Type char .......................................................... 29 Type Double ..................................................... 25 Type int ............................................................. 29 Type Long Double ............................................ 28 Type long int ..................................................... 30 Type long long int ............................................. 30 Type short int .................................................... 30 Type signed char .............................................. 30 Type Single....................................................... 27 Minute .....................................................137, 138, 143 mktime ................................................................... 142 modf ....................................................................... 176 modff ...................................................................... 177 modulus function Double Floating Point ..................................... 176 Single Floating Point ....................................... 177 Month .............................................. 137, 138, 142, 143 -msmart-io ................................................................ 43 Multibyte Character ...................................91, 105, 113 Maximum Number of Bytes............................... 30 Multibyte String ...............................................105, 113 N NaN ........................................................................ 147 Natural Logarithm Double Floating Point ..................................... 172 Single Floating Point ....................................... 175 NDEBUG.................................................................. 13 Nearest Integer Functions ceil .................................................................. 154 ceilf ................................................................. 155 floor ................................................................. 162 floorf ................................................................ 162 Nested Signal Handler ............................................. 32 Newline ..................................19, 43, 55, 60, 71, 72, 76 No Buffering ............................................ 43, 46, 81, 82 Non-Local Jumps, See setjmp.h NSETJMP ................................................................ 32 NULL....................................... 31, 41, 47, 91, 114, 138 O Object Module Format ............................................... 8 Octal.................................................... 74, 80, 111, 112 Octal Conversion ..................................................... 73 offsetof ..................................................................... 42 OMF ........................................................................... 8 open ....................................................................... 193 Output Formats ........................................................ 43 Overflow Errors .. 23, 147, 159, 160, 169, 170, 178, 179 Overlap ........................... 117, 118, 120, 123, 126, 129 P Pad Characters ........................................................ 73 Percent.................................................. 74, 79, 80, 143 Peripheral Libraries .................................................... 8 (c) 2008 Microchip Technology Inc. perror........................................................................ 72 pic30-libs __attach_input_file.......................................... 197 __C30_UART.................................................. 198 __close_input_file ........................................... 197 __delay32 ....................................................... 198 _erase_eedata ................................................ 199 _erase_eedata_all .......................................... 199 _erase_flash ................................................... 201 _exit ................................................................ 191 _init_prog_address ......................................... 204 _memcpy_p2d16 ............................................ 203 _memcpy_p2d24 ............................................ 203 _strncpy_p2d16 .............................................. 204 _strncpy_p2d24 .............................................. 204 _wait_eedata................................................... 200 _write_eedata_row.......................................... 200 _write_eedata_word........................................ 200 _write_flash_word16 ....................................... 202 _write_flash_word24 ....................................... 202 _write_flash16................................................. 201 _write_flash24................................................. 201 brk ................................................................... 191 close................................................................ 192 getenv ............................................................. 196 lseek................................................................ 193 open ................................................................ 193 read................................................................. 194 remove ............................................................ 196 rename............................................................ 196 sbrk ................................................................. 194 system............................................................. 196 time ................................................................. 197 write ................................................................ 195 Plus Sign .................................................................. 73 Pointer, Temporary ................................................ 107 pow......................................................................... 178 Power Function Double Floating Point...................................... 178 Single Floating Point ....................................... 179 Power Functions pow ................................................................. 178 powf ................................................................ 179 powf........................................................................ 179 precision................................................................... 73 Prefix .................................................................. 20, 73 Print Formats............................................................ 43 Printable Character Defined.............................................................. 18 Test for.............................................................. 18 printf ................................................................... 43, 73 Processor Clocks per Second................................ 137 Processor Time .............................................. 137, 138 Pseudo-Random Number .............................. 107, 109 ptrdiff_t ..................................................................... 41 Punctuation Character Defined.............................................................. 18 Test for.............................................................. 18 Pushed Back ............................................................ 85 putc .......................................................................... 75 putchar ..................................................................... 76 DS51456E-page 237 16-Bit Language Tools Libraries puts .......................................................................... 76 Q Q15 Functions ........................................................ 209 Q16 Functions ........................................................ 218 qsort ................................................................. 96, 106 Quick Sort .............................................................. 106 R Radix ........................................................................ 27 raise ............................................ 33, 34, 35, 36, 37, 38 rand ................................................................ 107, 109 RAND_MAX ..................................................... 91, 107 Range....................................................................... 80 Range Error.............................. 23, 111, 112, 157, 158, .........................159, 160,169, 170, 178, 179,182, 183 read ........................................................................ 194 Reading, Recommended............................................ 3 realloc............................................................. 101, 107 Reallocate Memory ................................................ 107 Rebuilding the libpic30 library ................................ 190 Registered Functions ....................................... 92, 100 Remainder Double Floating Point...................................... 163 Single Floating Point ....................................... 165 Remainder Functions fmod ................................................................ 163 fmodf ............................................................... 165 remove ............................................................. 77, 196 rename ............................................................. 77, 196 Reset ................................................................ 91, 113 Reset File Pointer..................................................... 78 rewind..........................................................78, 85, 193 Rounding Mode ........................................................ 27 S sbrk ................................................................ 192, 194 Scan Formats ........................................................... 43 scanf................................................................... 43, 79 SCHAR_MAX ........................................................... 30 SCHAR_MIN ............................................................ 30 Search Functions memchr ........................................................... 114 strchr ............................................................... 121 strcspn ............................................................ 124 strpbrk ............................................................. 131 strrchr .............................................................. 132 strspn .............................................................. 133 strstr ................................................................ 134 strtok ............................................................... 135 Second ............................................137, 138, 140, 143 Seed ............................................................... 107, 109 Seek From Beginning of File ...................................... 64 From Current Position ....................................... 64 From End Of File............................................... 64 SEEK_CUR ........................................................ 47, 64 SEEK_END ........................................................ 48, 64 SEEK_SET......................................................... 48, 64 setbuf ............................................................43, 46, 81 setjmp....................................................................... 32 DS51456E-page 238 setjmp.h.................................................................... 32 jmp_buf ............................................................. 32 longjmp.............................................................. 32 setjmp................................................................ 32 setlocale ................................................................... 31 setvbuf.......................................................... 43, 46, 82 short int Maximum Value ................................................ 30 Minimum Value ................................................. 30 SHRT_MAX.............................................................. 30 SHRT_MIN ............................................................... 30 sig_atomic_t ............................................................. 33 SIG_DFL .................................................................. 33 SIG_ERR.................................................................. 33 SIG_IGN................................................................... 33 SIGABRT.................................................................. 34 SIGFPE .................................................................... 34 SIGILL ...................................................................... 35 SIGINT ..................................................................... 35 Signal Abnormal Termination....................................... 34 Error .................................................................. 33 Floating-Point Error ........................................... 34 Ignore ................................................................ 33 Illegal Instruction ............................................... 35 Interrupt............................................................. 35 Reporting........................................................... 37 Termination Request......................................... 36 signal .......................................................34, 35, 36, 38 Signal Handler.................................................... 33, 38 Signal Handler Type................................................. 33 Signal Handling, See signal.h signal.h ..................................................................... 33 raise .................................................................. 37 sig_atomic_t ...................................................... 33 SIG_DFL ........................................................... 33 SIG_ERR .......................................................... 33 SIG_IGN............................................................ 33 SIGABRT .......................................................... 34 SIGFPE ............................................................. 34 SIGILL ............................................................... 35 SIGINT .............................................................. 35 signal................................................................. 38 SIGSEGV .......................................................... 36 SIGTERM.......................................................... 36 signed char Maximum Value ................................................ 30 Minimum Value ................................................. 30 SIGSEGV ................................................................. 36 SIGTERM ................................................................. 36 sim30 simulator ...................................................... 190 sin........................................................................... 180 sine Double Floating Point...................................... 180 Single Floating Point ....................................... 181 sinf.......................................................................... 181 Single Precision Floating Point Machine Epsilon................................................ 26 Maximum Exponent (base 10) .......................... 26 Maximum Exponent (base 2) ............................ 27 (c) 2008 Microchip Technology Inc. Index Maximum Value ................................................ 26 Minimum Exponent (base 10) ........................... 27 Minimum Exponent (base 2) ............................. 27 Minimum Value ................................................. 27 Number of Binary Digits .................................... 26 Number of Decimal Digits ................................. 26 sinh ........................................................................ 182 sinhf ....................................................................... 183 size........................................................................... 74 size_t............................................. 41, 46, 90, 114, 137 sizeof............................................. 41, 46, 90, 114, 137 Sort, Quick ............................................................. 106 Source File Name .................................................... 13 Source Line Number ................................................ 13 Space ....................................................................... 73 Space Character Defined ............................................................. 19 Test for.............................................................. 19 Specifiers ............................................................73, 79 sprintf ..................................................................43, 83 sqrt ......................................................................... 184 sqrtf ........................................................................ 185 Square Root Function Double Floating Point ..................................... 184 Single Floating Point ....................................... 185 Square Root Functions sqrt .................................................................. 184 sqrtf ................................................................. 185 srand ...................................................................... 109 sscanf..................................................................43, 83 Stack ...................................................................... 192 Standard C Libraries ................................................ 11 Standard C Locale ................................................... 14 Standard Error ....................................................43, 48 Standard Input ....................................................43, 48 Standard Output..................................................43, 48 Start-up .................................................................... 43 Module, Alternate................................................ 8 Module, Primary.................................................. 8 stdarg.h .................................................................... 39 va_arg ............................................................... 39 va_end .............................................................. 41 va_list................................................................ 39 va_start ............................................................. 41 stddef.h .................................................................... 41 NULL................................................................. 41 offsetof .............................................................. 42 ptrdiff_t .............................................................. 41 size_t ................................................................ 41 wchar_t ............................................................. 41 stderr ................................................. 13, 43, 47, 48, 72 stdin .................................................. 43, 47, 48, 71, 79 stdio.h ...............................................................43, 196 _IOFBF ............................................................. 46 _IOLBF ............................................................. 46 _IONBF............................................................. 46 BUFSIZ ............................................................. 46 clearerr.............................................................. 49 EOF .................................................................. 46 fclose ................................................................ 50 (c) 2008 Microchip Technology Inc. feof .................................................................... 51 ferror ................................................................. 52 fflush ................................................................. 53 fgetc .................................................................. 53 fgetpos .............................................................. 54 fgets .................................................................. 55 FILE .................................................................. 45 FILENAME_MAX .............................................. 46 fopen ................................................................. 56 FOPEN_MAX.................................................... 46 fpos_t ................................................................ 45 fprintf ................................................................. 58 fputc .................................................................. 59 fputs .................................................................. 59 fread.................................................................. 60 freopen.............................................................. 62 fscanf ................................................................ 62 fseek ................................................................. 64 fsetpos .............................................................. 65 ftell .................................................................... 67 fwrite ................................................................. 68 getc ................................................................... 70 getchar .............................................................. 71 gets ................................................................... 71 L_tmpnam ......................................................... 47 NULL................................................................. 47 perror ................................................................ 72 printf .................................................................. 73 putc ................................................................... 75 putchar .............................................................. 76 puts ................................................................... 76 remove .............................................................. 77 rename.............................................................. 77 rewind ............................................................... 78 scanf ................................................................. 79 SEEK_CUR....................................................... 47 SEEK_END....................................................... 48 SEEK_SET ....................................................... 48 setbuf ................................................................ 81 setvbuf .............................................................. 82 size_t................................................................. 46 sprintf ................................................................ 83 sscanf................................................................ 83 stderr................................................................. 48 stdin .................................................................. 48 stdout ................................................................ 48 TMP_MAX......................................................... 48 tmpfile ............................................................... 84 tmpnam ............................................................. 85 ungetc ............................................................... 85 vfprintf ............................................................... 87 vprintf ................................................................ 88 vsprintf .............................................................. 89 stdlib.h.............................................................. 90, 196 abort.................................................................. 91 abs .................................................................... 92 atexit ................................................................. 92 atof .................................................................... 94 atoi .................................................................... 95 atol .................................................................... 95 DS51456E-page 239 16-Bit Language Tools Libraries bsearch ............................................................. 96 calloc ................................................................. 98 div ..................................................................... 98 div_t .................................................................. 90 exit .................................................................. 100 EXIT_FAILURE ................................................. 90 EXIT_SUCCESS............................................... 90 free .................................................................. 101 getenv ............................................................. 101 labs ................................................................. 102 ldiv................................................................... 103 ldiv_t.................................................................. 90 malloc.............................................................. 104 MB_CUR_MAX ................................................. 91 mblen .............................................................. 105 mbstowcs ........................................................ 105 mbtowc............................................................ 105 NULL................................................................. 91 qsort ................................................................ 106 rand ................................................................. 107 RAND_MAX ...................................................... 91 realloc ............................................................. 107 size_t................................................................. 90 srand ............................................................... 109 strtod ............................................................... 109 strtol ................................................................ 111 strtoul .............................................................. 112 system............................................................. 113 wchar_t ............................................................. 90 wctomb............................................................ 113 wxstombs ........................................................ 113 stdout ................................................ 43, 47, 48, 73, 76 strcat ...................................................................... 120 strchr ...................................................................... 121 strcmp .................................................................... 122 strcoll ...................................................................... 123 strcpy...................................................................... 123 strcspn.................................................................... 124 Streams .................................................................... 43 Binary ................................................................ 43 Buffering............................................................ 82 Closing ...................................................... 50, 100 Opening ............................................................ 56 Reading From ................................................... 70 Text ................................................................... 43 Writing To.................................................... 68, 75 strerror.................................................................... 125 strftime ................................................................... 142 String Length ............................................................. 125 Search............................................................. 134 Transform........................................................ 136 String Functions, See string.h string.h ................................................................... 114 memchr ........................................................... 114 memcmp ......................................................... 115 memcpy .......................................................... 117 memmove ....................................................... 118 memset ........................................................... 119 NULL............................................................... 114 DS51456E-page 240 size_t............................................................... 114 strcat ............................................................... 120 strchr ............................................................... 121 strcmp ............................................................. 122 strcoll............................................................... 123 strcpy............................................................... 123 strcspn............................................................. 124 strerror............................................................. 125 strlen ............................................................... 125 strncat ............................................................. 126 strncmp ........................................................... 128 strncpy............................................................. 129 strpbrk ............................................................. 131 strrchr .............................................................. 132 strspn .............................................................. 133 strstr ................................................................ 134 strtok ............................................................... 135 strxfrm ............................................................. 136 strlen....................................................................... 125 strncat..................................................................... 126 strncmp................................................................... 128 strncpy.................................................................... 129 strncpy_p2d16........................................................ 204 strncpy_p2d24........................................................ 204 strpbrk .................................................................... 131 strrchr ..................................................................... 132 strspn...................................................................... 133 strstr ....................................................................... 134 strtod ................................................................ 94, 109 strtok....................................................................... 135 strtol.................................................................. 95, 111 strtoul...................................................................... 112 struct lconv ............................................................... 31 struct tm.................................................................. 137 strxfrm .................................................................... 136 Substrings .............................................................. 135 Subtracting Pointers ................................................. 41 Successful Termination ............................................ 90 Support Library....................................................... 189 system ............................................................ 113, 196 T Tab ........................................................................... 19 tan .......................................................................... 186 tanf ......................................................................... 186 tangent Double Floating Point...................................... 186 Single Floating Point ....................................... 186 tanh ........................................................................ 187 tanhf ....................................................................... 188 Temporary File ............................................................ 84, 100 Filename ..................................................... 47, 85 Pointer............................................................. 107 Termination Request Message ............................................. 36 Request Signal.................................................. 36 Successful......................................................... 90 Unsuccessful..................................................... 90 Text Mode ................................................................ 56 Text Streams ............................................................ 43 (c) 2008 Microchip Technology Inc. Index Ticks........................................................137, 138, 140 time .................................................................144, 197 Time Difference...................................................... 140 Time Structure ................................................137, 142 Time Zone .............................................................. 143 time_t ......................................................137, 142, 144 time.h ..............................................................137, 197 asctime ........................................................... 138 clock................................................................ 138 clock_t............................................................. 137 CLOCKS_PER_SEC ...................................... 137 ctime ............................................................... 139 difftime ............................................................ 140 gmtime ............................................................ 140 localtime.......................................................... 141 mktime ............................................................ 142 NULL............................................................... 138 size_t .............................................................. 137 strftime ............................................................ 142 struct tm .......................................................... 137 time ................................................................. 144 time_t .............................................................. 137 TMP_MAX................................................................ 48 tmpfile ...................................................................... 84 tmpnam .................................................................... 85 Tokens ................................................................... 135 tolower ..................................................................... 21 toupper ..................................................................... 22 Transferring Control ................................................. 32 Transform String .................................................... 136 Trigonometric Functions acos ................................................................ 147 acosf ............................................................... 148 asin ................................................................. 149 asinf ................................................................ 149 atan ................................................................. 150 atan2............................................................... 151 atan2f .............................................................. 153 atanf................................................................ 151 cos .................................................................. 155 cosf ................................................................. 156 sin ................................................................... 180 sinf .................................................................. 181 tan ................................................................... 186 tanf .................................................................. 186 type .....................................................................74, 80 U UCHAR_MAX .......................................................... 31 UINT_MAX ............................................................... 31 ULLONG_MAX ........................................................ 31 ULONG_MAX .......................................................... 31 Underflow Errors 23, 147, 159, 160, 169, 170, 178, 179 ungetc ...................................................................... 85 Universal Time Coordinated................................... 140 unsigned char Maximum Value ................................................ 31 unsigned int Maximum Value ................................................ 31 unsigned short int Maximum Value ................................................ 31 (c) 2008 Microchip Technology Inc. Unsuccessful Termination........................................ 90 Upper Case Alphabetic Character Convert To ........................................................ 22 Defined.............................................................. 20 Test for.............................................................. 20 USHRT_MAX ........................................................... 31 UTC........................................................................ 140 Utility Functions, See stdlib.h V va_arg ............................................... 39, 41, 87, 88, 89 va_end .................................................... 41, 87, 88, 89 va_list ....................................................................... 39 va_start ................................................... 41, 87, 88, 89 Variable Argument Lists, See stdarg.h Variable Length Argument List.......... 39, 41, 87, 88, 89 VERBOSE_DEBUGGING ........................................ 13 Vertical Tab .............................................................. 19 vfprintf ................................................................ 43, 87 vprintf ................................................................. 43, 88 vsprintf................................................................ 43, 89 W wait_eedata............................................................ 200 wchar_t............................................................... 41, 90 wcstombs ............................................................... 113 wctomb................................................................... 113 Web Site, Microchip ................................................... 4 Week ...................................................................... 143 White Space.......................................... 79, 94, 95, 109 White-Space Character Defined.............................................................. 19 Test for.............................................................. 19 wide.......................................................................... 90 Wide Character .............................................. 105, 113 Wide Character String.................................... 105, 113 Wide Character Value .............................................. 41 Width ........................................................................ 73 width................................................................... 73, 79 write........................................................................ 195 write_eedata_row................................................... 200 write_eedata_word................................................. 200 write_flash_word16 ................................................ 202 write_flash_word24 ................................................ 202 write_flash16 .......................................................... 201 write_flash24 .......................................................... 201 Y Year.........................................................137, 138, 143 Z Zero........................................................................ 147 Zero, divide by...............................................34, 37, 98 DS51456E-page 241 WORLDWIDE SALES AND SERVICE AMERICAS ASIA/PACIFIC ASIA/PACIFIC EUROPE Corporate Office 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: http://support.microchip.com Web Address: www.microchip.com Asia Pacific Office Suites 3707-14, 37th Floor Tower 6, The Gateway Harbour City, Kowloon Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431 India - 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