--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/libavutil/crc.h	Tue Dec 31 14:52:14 2013 +0000
@@ -0,0 +1,74 @@
+/*
+ * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_CRC_H
+#define AVUTIL_CRC_H
+
+#include <stdint.h>
+#include <stddef.h>
+#include "attributes.h"
+
+typedef uint32_t AVCRC;
+
+typedef enum {
+    AV_CRC_8_ATM,
+    AV_CRC_16_ANSI,
+    AV_CRC_16_CCITT,
+    AV_CRC_32_IEEE,
+    AV_CRC_32_IEEE_LE,  /*< reversed bitorder version of AV_CRC_32_IEEE */
+    AV_CRC_MAX,         /*< Not part of public API! Do not use outside libavutil. */
+}AVCRCId;
+
+/**
+ * Initialize a CRC table.
+ * @param ctx must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
+ * @param le If 1, the lowest bit represents the coefficient for the highest
+ *           exponent of the corresponding polynomial (both for poly and
+ *           actual CRC).
+ *           If 0, you must swap the CRC parameter and the result of av_crc
+ *           if you need the standard representation (can be simplified in
+ *           most cases to e.g. bswap16):
+ *           av_bswap32(crc << (32-bits))
+ * @param bits number of bits for the CRC
+ * @param poly generator polynomial without the x**bits coefficient, in the
+ *             representation as specified by le
+ * @param ctx_size size of ctx in bytes
+ * @return <0 on failure
+ */
+int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size);
+
+/**
+ * Get an initialized standard CRC table.
+ * @param crc_id ID of a standard CRC
+ * @return a pointer to the CRC table or NULL on failure
+ */
+const AVCRC *av_crc_get_table(AVCRCId crc_id);
+
+/**
+ * Calculate the CRC of a block.
+ * @param crc CRC of previous blocks if any or initial value for CRC
+ * @return CRC updated with the data from the given block
+ *
+ * @see av_crc_init() "le" parameter
+ */
+uint32_t av_crc(const AVCRC *ctx, uint32_t crc,
+                const uint8_t *buffer, size_t length) av_pure;
+
+#endif /* AVUTIL_CRC_H */