path: root/private/crt32/string/memcmp.c

/***
*memcmp.c - compare two blocks of memory
*
*	Copyright (c) 1985-1991, Microsoft Corporation. All rights reserved.
*
*Purpose:
*	defines memcmp() - compare two memory blocks lexically and
*	find their order.
*
*Revision History:
*	05-31-89   JCR	C version created.
*	02-27-90   GJF	Fixed calling type, #include <cruntime.h>, fixed
*			copyright.
*	10-01-90   GJF	New-style function declarator. Also, rewrote expr. to
*			avoid using cast as an lvalue.
*	04-01-91   SRW	Add #pragma function for i386 _WIN32_ and _CRUISER_
*			builds
*	10-11-91   GJF	Bug fix! Comparison of final bytes must use unsigned
*			chars.
*
*******************************************************************************/

#include <cruntime.h>
#include <string.h>

#if	defined(_CRUISER_) || defined(i386)
#pragma function(memcmp)
#endif  /* ndef _CRUISER_ */

/***
*int memcmp(buf1, buf2, count) - compare memory for lexical order
*
*Purpose:
*	Compares count bytes of memory starting at buf1 and buf2
*	and find if equal or which one is first in lexical order.
*
*Entry:
*	void *buf1, *buf2 - pointers to memory sections to compare
*	size_t count - length of sections to compare
*
*Exit:
*	returns < 0 if buf1 < buf2
*	returns  0  if buf1 == buf2
*	returns > 0 if buf1 > buf2
*
*Exceptions:
*
*******************************************************************************/

int _CALLTYPE1 memcmp (
	const void * buf1,
	const void * buf2,
	size_t count
	)
{
	if (!count)
		return(0);

	while ( --count && *(char *)buf1 == *(char *)buf2 ) {
		buf1 = (char *)buf1 + 1;
		buf2 = (char *)buf2 + 1;
	}

	return( *((unsigned char *)buf1) - *((unsigned char *)buf2) );
}