70 lines
1.4 KiB
C
70 lines
1.4 KiB
C
/* memcmp.c - memory compare file for string */
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/* Copyright 1992-1993 Wind River Systems, Inc. */
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/*
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modification history
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--------------------
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01c,25feb93,jdi documentation cleanup for 5.1.
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01b,20sep92,smb documentation additions
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01a,08jul92,smb written and documented.
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*/
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/*
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DESCRIPTION
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INCLUDE FILE: string.h
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SEE ALSO: American National Standard X3.159-1989
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NOMANUAL
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*/
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#include "vxWorks.h"
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#include "string.h"
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/*******************************************************************************
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*
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* memcmp - compare two blocks of memory (ANSI)
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*
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* This routine compares successive elements from two arrays of `unsigned char',
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* beginning at the addresses <s1> and <s2> (both of size <n>), until it finds
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* elements that are not equal.
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*
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* INCLUDE FILES: string.h
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*
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* RETURNS:
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* If all elements are equal, zero. If elements differ and the differing
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* element from <s1> is greater than the element from <s2>, the routine
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* returns a positive number; otherwise, it returns a negative number.
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*/
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int memcmp
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(
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const void * s1, /* array 1 */
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const void * s2, /* array 2 */
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size_t n /* size of memory to compare */
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)
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{
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const unsigned char *p1;
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const unsigned char *p2;
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/* size of memory is zero */
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if (n == 0)
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return (0);
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/* compare array 2 into array 1 */
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p1 = s1;
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p2 = s2;
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while (*p1++ == *p2++)
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{
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if (--n == 0)
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return (0);
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}
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return ((*--p1) - (*--p2));
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}
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