openldap/libraries/liblutil/hash.c

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/* $OpenLDAP$ */
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/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
*
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* Copyright 2000-2004 The OpenLDAP Foundation.
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* Portions Copyright 2000-2003 Kurt D. Zeilenga.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted only as authorized by the OpenLDAP
* Public License.
*
* A copy of this license is available in the file LICENSE in the
* top-level directory of the distribution or, alternatively, at
* <http://www.OpenLDAP.org/license.html>.
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*/
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/* This implements the Fowler / Noll / Vo (FNV-1) hash algorithm.
* A summary of the algorithm can be found at:
* http://www.isthe.com/chongo/tech/comp/fnv/index.html
*/
#include "portable.h"
#include <lutil_hash.h>
/* offset and prime for 32-bit FNV-1 */
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#define HASH_OFFSET 0x811c9dc5U
#define HASH_PRIME 16777619
/*
* Initialize context
*/
void
lutil_HASHInit( struct lutil_HASHContext *ctx )
{
ctx->hash = HASH_OFFSET;
}
/*
* Update hash
*/
void
lutil_HASHUpdate(
struct lutil_HASHContext *ctx,
const unsigned char *buf,
ber_len_t len
)
{
const unsigned char *p, *e;
ber_uint_t h;
p = buf;
e = &buf[len];
h = ctx->hash;
while( p < e ) {
h *= HASH_PRIME;
h ^= *p++;
}
ctx->hash = h;
}
/*
* Save hash
*/
void
lutil_HASHFinal( unsigned char *digest, struct lutil_HASHContext *ctx )
{
ber_uint_t h = ctx->hash;
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digest[0] = h & 0xffU;
digest[1] = (h>>8) & 0xffU;
digest[2] = (h>>16) & 0xffU;
digest[3] = (h>>24) & 0xffU;
}