repositories / deb_ffmpeg.git / blame
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| 2ba45a60 DM |
1 | /* |
| 2 | * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> | |
| 3 | * | |
| 4 | * This file is part of FFmpeg. | |
| 5 | * | |
| 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. | |
| 10 | * | |
| 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. | |
| 15 | * | |
| 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 | |
| 19 | */ | |
| 20 | ||
| 21 | #ifndef AVUTIL_CRC_H | |
| 22 | #define AVUTIL_CRC_H | |
| 23 | ||
| 24 | #include <stdint.h> | |
| 25 | #include <stddef.h> | |
| 26 | #include "attributes.h" | |
| 27 | ||
| 28 | /** | |
| 29 | * @defgroup lavu_crc32 CRC32 | |
| 30 | * @ingroup lavu_crypto | |
| 31 | * @{ | |
| 32 | */ | |
| 33 | ||
| 34 | typedef uint32_t AVCRC; | |
| 35 | ||
| 36 | typedef enum { | |
| 37 | AV_CRC_8_ATM, | |
| 38 | AV_CRC_16_ANSI, | |
| 39 | AV_CRC_16_CCITT, | |
| 40 | AV_CRC_32_IEEE, | |
| 41 | AV_CRC_32_IEEE_LE, /*< reversed bitorder version of AV_CRC_32_IEEE */ | |
| 42 | AV_CRC_16_ANSI_LE, /*< reversed bitorder version of AV_CRC_16_ANSI */ | |
| 43 | AV_CRC_24_IEEE = 12, | |
| 44 | AV_CRC_MAX, /*< Not part of public API! Do not use outside libavutil. */ | |
| 45 | }AVCRCId; | |
| 46 | ||
| 47 | /** | |
| 48 | * Initialize a CRC table. | |
| 49 | * @param ctx must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024 | |
| 50 | * @param le If 1, the lowest bit represents the coefficient for the highest | |
| 51 | * exponent of the corresponding polynomial (both for poly and | |
| 52 | * actual CRC). | |
| 53 | * If 0, you must swap the CRC parameter and the result of av_crc | |
| 54 | * if you need the standard representation (can be simplified in | |
| 55 | * most cases to e.g. bswap16): | |
| 56 | * av_bswap32(crc << (32-bits)) | |
| 57 | * @param bits number of bits for the CRC | |
| 58 | * @param poly generator polynomial without the x**bits coefficient, in the | |
| 59 | * representation as specified by le | |
| 60 | * @param ctx_size size of ctx in bytes | |
| 61 | * @return <0 on failure | |
| 62 | */ | |
| 63 | int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size); | |
| 64 | ||
| 65 | /** | |
| 66 | * Get an initialized standard CRC table. | |
| 67 | * @param crc_id ID of a standard CRC | |
| 68 | * @return a pointer to the CRC table or NULL on failure | |
| 69 | */ | |
| 70 | const AVCRC *av_crc_get_table(AVCRCId crc_id); | |
| 71 | ||
| 72 | /** | |
| 73 | * Calculate the CRC of a block. | |
| 74 | * @param crc CRC of previous blocks if any or initial value for CRC | |
| 75 | * @return CRC updated with the data from the given block | |
| 76 | * | |
| 77 | * @see av_crc_init() "le" parameter | |
| 78 | */ | |
| 79 | uint32_t av_crc(const AVCRC *ctx, uint32_t crc, | |
| 80 | const uint8_t *buffer, size_t length) av_pure; | |
| 81 | ||
| 82 | /** | |
| 83 | * @} | |
| 84 | */ | |
| 85 | ||
| 86 | #endif /* AVUTIL_CRC_H */ |