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63 lines
1.6 KiB
C
63 lines
1.6 KiB
C
/* GStreamer
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* Copyright (C) 2007 Thomas Vander Stichele <thomas at apestaart dot org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <glib.h>
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#include "fnv1hash.h"
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/* This file implements FNV-1 hashing used in the Ogg payload encoders
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* to generate the 24-bit ident value based on the header pages.
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* See http://isthe.com/chongo/tech/comp/fnv/
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*/
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#define MASK_24 (((guint32) 1 << 24) -1)
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#define FNV1_HASH_32_INIT ((guint32) 0x811C9DC5L)
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//2166136261L)
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#define FNV1_HASH_32_PRIME 16777619
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guint32
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fnv1_hash_32_new (void)
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{
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return FNV1_HASH_32_INIT;
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}
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guint32
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fnv1_hash_32_update (guint32 hash, const guchar * data, guint length)
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{
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guint i;
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const guchar *p = data;
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for (i = 0; i < length; ++i, ++p) {
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hash *= FNV1_HASH_32_PRIME;
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hash ^= *p;
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}
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return hash;
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}
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guint32
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fnv1_hash_32_to_24 (guint32 hash)
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{
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return (hash >> 24) ^ (hash & MASK_24);
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}
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