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/* GStreamer
* Copyright (C) 2007 Thomas Vander Stichele <thomas at apestaart dot org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <glib.h>
#include "fnv1hash.h"
/* This file implements FNV-1 hashing used in the Ogg payload encoders
* to generate the 24-bit ident value based on the header pages.
* See http://isthe.com/chongo/tech/comp/fnv/
*/
#define MASK_24 (((guint32) 1 << 24) -1)
#define FNV1_HASH_32_INIT ((guint32) 0x811C9DC5L)
//2166136261L)
#define FNV1_HASH_32_PRIME 16777619
guint32
fnv1_hash_32_new (void)
{
return FNV1_HASH_32_INIT;
}
guint32
fnv1_hash_32_update (guint32 hash, const guchar * data, guint length)
{
guint i;
const guchar *p = data;
for (i = 0; i < length; ++i, ++p) {
hash *= FNV1_HASH_32_PRIME;
hash ^= *p;
}
return hash;
}
guint32
fnv1_hash_32_to_24 (guint32 hash)
{
return (hash >> 24) ^ (hash & MASK_24);
}
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