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/* $NetBSD: consttime_memequal.c,v 1.4 2013/08/28 19:31:14 riastradh Exp $ */
#if !defined(_KERNEL) && !defined(_STANDALONE)
#include "namespace.h"
#include <string.h>
#ifdef __weak_alias
__weak_alias(consttime_memequal,_consttime_memequal)
#endif
#else
#include <lib/libkern/libkern.h>
#endif
int
consttime_memequal(const void *b1, const void *b2, size_t len)
{
const char *c1 = b1, *c2 = b2;
int res = 0;
while (len --)
res |= *c1++ ^ *c2++;
/*
* If the compiler for your favourite architecture generates a
* conditional branch for `!res', it will be a data-dependent
* branch, in which case this should be replaced by
*
* return (1 - (1 & ((res - 1) >> 8)));
*
* or rewritten in assembly.
*/
return !res;
}
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