2 * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
4 * This file is part of FFmpeg.
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 #include "attributes.h"
30 * @defgroup lavu_crc32 CRC32
31 * @ingroup lavu_crypto
35 typedef uint32_t AVCRC;
42 AV_CRC_32_IEEE_LE, /*< reversed bitorder version of AV_CRC_32_IEEE */
43 AV_CRC_16_ANSI_LE, /*< reversed bitorder version of AV_CRC_16_ANSI */
44 #if FF_API_CRC_BIG_TABLE
48 #endif /* FF_API_CRC_BIG_TABLE */
49 AV_CRC_MAX, /*< Not part of public API! Do not use outside libavutil. */
53 * Initialize a CRC table.
54 * @param ctx must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
55 * @param le If 1, the lowest bit represents the coefficient for the highest
56 * exponent of the corresponding polynomial (both for poly and
58 * If 0, you must swap the CRC parameter and the result of av_crc
59 * if you need the standard representation (can be simplified in
60 * most cases to e.g. bswap16):
61 * av_bswap32(crc << (32-bits))
62 * @param bits number of bits for the CRC
63 * @param poly generator polynomial without the x**bits coefficient, in the
64 * representation as specified by le
65 * @param ctx_size size of ctx in bytes
66 * @return <0 on failure
68 int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size);
71 * Get an initialized standard CRC table.
72 * @param crc_id ID of a standard CRC
73 * @return a pointer to the CRC table or NULL on failure
75 const AVCRC *av_crc_get_table(AVCRCId crc_id);
78 * Calculate the CRC of a block.
79 * @param crc CRC of previous blocks if any or initial value for CRC
80 * @return CRC updated with the data from the given block
82 * @see av_crc_init() "le" parameter
84 uint32_t av_crc(const AVCRC *ctx, uint32_t crc,
85 const uint8_t *buffer, size_t length) av_pure;
91 #endif /* AVUTIL_CRC_H */