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/* Chrysalide - Outil d'analyse de fichiers binaires
* fnv1a.c - implémentaton du calcul rapide d'empreintes de chaînes
*
* Copyright (C) 2012 Cyrille Bagard
*
* This file is part of Chrysalide.
*
* Chrysalide is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* Chrysalide is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Foobar. If not, see <http://www.gnu.org/licenses/>.
*/
#include "fnv1a.h"
/* Constante d'initialisation */
#define FNV1A_64_INIT 0xcbf29ce484222325ull
/* Coefficient magique ! */
#define FNV_64_PRIME 0x100000001b3ull
/******************************************************************************
* *
* Paramètres : a = première empreinte à manipuler. *
* b = seconde empreinte à manipuler. *
* *
* Description : Détermine si deux empreintes FNV1a sont indentiques ou non. *
* *
* Retour : Bilan de la comparaison : -1, 0 ou 1. *
* *
* Remarques : - *
* *
******************************************************************************/
int cmp_fnv_64a(fnv64_t a, fnv64_t b)
{
int result; /* Bilan à retourner */
if (a < b) result = -1;
else if (a == b) result = 0;
else result = 1;
return result;
}
/******************************************************************************
* *
* Paramètres : str = chaîne de caractères à traiter. *
* *
* Description : Détermine l'empreinte FNV1a d'une chaîne de caractères. *
* *
* Retour : Valeur calculée. *
* *
* Remarques : - *
* *
******************************************************************************/
fnv64_t fnv_64a_hash(const char *str)
{
fnv64_t result; /* Valeur à retourner */
unsigned char *iter; /* Boucle de parcours */
result = FNV1A_64_INIT;
for (iter = (unsigned char *)str; *iter; iter++)
{
result ^= (fnv64_t)*iter;
result *= FNV_64_PRIME;
}
return result;
}
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