diff options
Diffstat (limited to 'gst/rtp/fnv1hash.c')
-rw-r--r-- | gst/rtp/fnv1hash.c | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/gst/rtp/fnv1hash.c b/gst/rtp/fnv1hash.c new file mode 100644 index 0000000..a7926e4 --- /dev/null +++ b/gst/rtp/fnv1hash.c @@ -0,0 +1,63 @@ +/* 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); +} |