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/*
FUNCTION
<<memcmp>>---compare two memory areas
INDEX
memcmp
SYNOPSIS
#include <string.h>
int memcmp(const void *<[s1]>, const void *<[s2]>, size_t <[n]>);
DESCRIPTION
This function compares not more than <[n]> characters of the
object pointed to by <[s1]> with the object pointed to by <[s2]>.
RETURNS
The function returns an integer greater than, equal to or
less than zero according to whether the object pointed to by
<[s1]> is greater than, equal to or less than the object
pointed to by <[s2]>.
PORTABILITY
<<memcmp>> is ANSI C.
<<memcmp>> requires no supporting OS subroutines.
QUICKREF
memcmp ansi pure
*/
#include <string.h>
#include "local.h"
int
memcmp (const void *m1,
const void *m2,
size_t n)
{
#if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
unsigned char *s1 = (unsigned char *) m1;
unsigned char *s2 = (unsigned char *) m2;
while (n--)
{
if (*s1 != *s2)
{
return *s1 - *s2;
}
s1++;
s2++;
}
return 0;
#else
unsigned char *s1 = (unsigned char *) m1;
unsigned char *s2 = (unsigned char *) m2;
unsigned long *a1;
unsigned long *a2;
/* If the size is too small, or either pointer is unaligned,
then we punt to the byte compare loop. Hopefully this will
not turn up in inner loops. */
if (!TOO_SMALL_LITTLE_BLOCK(n) && !UNALIGNED_X_Y(s1,s2))
{
/* Otherwise, load and compare the blocks of memory one
word at a time. */
a1 = (unsigned long*) s1;
a2 = (unsigned long*) s2;
while (!TOO_SMALL_LITTLE_BLOCK(n))
{
if (*a1 != *a2)
break;
a1++;
a2++;
n -= LITTLE_BLOCK_SIZE;
}
/* check m mod LITTLE_BLOCK_SIZE remaining characters */
s1 = (unsigned char*)a1;
s2 = (unsigned char*)a2;
}
while (n--)
{
if (*s1 != *s2)
return *s1 - *s2;
s1++;
s2++;
}
return 0;
#endif /* not PREFER_SIZE_OVER_SPEED */
}
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