/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
#include "tomcrypt.h"
/**
@file mem_neq.c
Compare two blocks of memory for inequality.
Steffen Jaeckel
*/
/**
Compare two blocks of memory for inequality.
The usage is similar to that of standard memcmp(), but you can only test
if the memory is equal or not - you can not determine by how much the
first different byte differs.
@param a The first memory region
@param b The second memory region
@param len The length of the area to compare (octets)
@return 0 when a and b are equal for len bytes, else they are not equal.
*/
int mem_neq(const void *a, const void *b, size_t len)
{
unsigned char ret = 0;
const unsigned char* pa;
const unsigned char* pb;
LTC_ARGCHK(a != NULL);
LTC_ARGCHK(b != NULL);
pa = a;
pb = b;
while (len-- > 0) {
ret |= *pa ^ *pb;
++pa;
++pb;
}
ret |= ret >> 4;
ret |= ret >> 2;
ret |= ret >> 1;
ret &= 1;
return ret;
}
/* $Source$ */
/* $Revision$ */
/* $Date$ */