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Cx51 User's Guide

Cx51 Introduction Compiling Programs Language Extensions Preprocessor Advanced Programming 8051 Derivatives Error Messages Library Reference Library Files Source Code Standard Types jmp_buf size_t va_list wchar_t Macros CBYTE CWORD DBYTE DWORD FARRAY FCARRAY FCVAR FVAR PBYTE PWORD XBYTE XWORD Routines By Category Buffer Manipulation Routines Character Routines Data Conversion Routines Intrinsic Routines Math Routines Memory Allocation Routines Stream I/O Routines String Routines Variable Length Argument Routines Miscellaneous Routines Include Files SFR Definitions 80c517.h absacc.h assert.h ctype.h float.h intrins.h limits.h math.h rtx51tny.h setjmp.h stdarg.h stddef.h stdio.h stdlib.h string.h Reference _chkfloat_ _crol_ _cror_ _getkey _irol_ _iror_ _lrol_ _lror_ _nop_ _pop_ _push_ _testbit_ _tolower _toupper abs acos acos517 asin asin517 assert atan atan2 atan517 atof atof517 atoi atol cabs calloc ceil cos cos517 cosh exp exp517 fabs floor fmod free getchar gets init_mempool isalnum isalpha iscntrl isdigit isgraph islower isprint ispunct isspace isupper isxdigit labs log log10 log10517 log517 longjmp malloc memccpy memchr memcmp memcpy memmove memset modf offsetof pow printf printf517 putchar puts rand realloc scanf scanf517 setjmp sin sin517 sinh sprintf sprintf517 sqrt sqrt517 srand sscanf sscanf517 strcat strchr strcmp strcpy strcspn strlen strncat strncmp strncpy strpbrk strpos strrchr strrpbrk strrpos strspn strstr strtod strtod517 strtok strtol strtoul switchbank tan tan517 tanh toascii toint tolower toupper ungetchar va_arg va_end va_start vprintf vsprintf Appendix

Memory Allocation Routines

Routine Attributes Description
calloc   Allocates storage for an array from the memory pool.
free   Frees a memory block that was allocated using calloc, malloc, or realloc.
init_mempool   Initializes the memory location and size of the memory pool.
malloc   Allocates a block from the memory pool.
realloc   Reallocates a block from the memory pool.

Use the memory allocation functions to specify, allocate, and free blocks of memory from a memory pool. All memory allocation functions are implemented as functions and are prototyped in the stdlib.h include file.

Before using any of these functions to allocate memory, you must first specify the size and location of the memory pool using the init_mempool routine. All memory requests are satisfied using this memory block.

The calloc and malloc routines allocate blocks of memory from the pool. The calloc routine allocates an array with a specified number of elements of a given size and initializes the array to 0. The malloc routine allocates a specified number of bytes.

The realloc routine changes the size of an allocated block while the free routine returns a previously allocated memory block to the memory pool.

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