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-rw-r--r--gst/rtp/fnv1hash.c63
1 files changed, 63 insertions, 0 deletions
diff --git a/gst/rtp/fnv1hash.c b/gst/rtp/fnv1hash.c
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+++ b/gst/rtp/fnv1hash.c
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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);
+}