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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 4349 | Serge | 1 | /* |
| 2 | * copyright (c) 2006 Michael Niedermayer |
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| 3 | * |
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| 4 | * This file is part of FFmpeg. |
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| 5 | * |
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| 6 | * FFmpeg is free software; you can redistribute it and/or |
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| 7 | * modify it under the terms of the GNU Lesser General Public |
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| 8 | * License as published by the Free Software Foundation; either |
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| 9 | * version 2.1 of the License, or (at your option) any later version. |
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| 10 | * |
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| 11 | * FFmpeg is distributed in the hope that it will be useful, |
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| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 14 | * Lesser General Public License for more details. |
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| 15 | * |
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| 16 | * You should have received a copy of the GNU Lesser General Public |
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| 17 | * License along with FFmpeg; if not, write to the Free Software |
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| 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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| 19 | */ |
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| 20 | |||
| 21 | #ifndef AVUTIL_CRC_H |
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| 22 | #define AVUTIL_CRC_H |
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| 23 | |||
| 24 | #include |
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| 25 | #include |
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| 26 | #include "attributes.h" |
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| 27 | |||
| 28 | /** |
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| 29 | * @defgroup lavu_crc32 CRC32 |
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| 30 | * @ingroup lavu_crypto |
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| 31 | * @{ |
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| 32 | */ |
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| 33 | |||
| 34 | typedef uint32_t AVCRC; |
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| 35 | |||
| 36 | typedef enum { |
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| 37 | AV_CRC_8_ATM, |
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| 38 | AV_CRC_16_ANSI, |
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| 39 | AV_CRC_16_CCITT, |
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| 40 | AV_CRC_32_IEEE, |
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| 41 | AV_CRC_32_IEEE_LE, /*< reversed bitorder version of AV_CRC_32_IEEE */ |
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| 42 | AV_CRC_24_IEEE = 12, |
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| 43 | AV_CRC_MAX, /*< Not part of public API! Do not use outside libavutil. */ |
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| 44 | }AVCRCId; |
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| 45 | |||
| 46 | /** |
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| 47 | * Initialize a CRC table. |
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| 48 | * @param ctx must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024 |
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| 49 | * @param le If 1, the lowest bit represents the coefficient for the highest |
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| 50 | * exponent of the corresponding polynomial (both for poly and |
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| 51 | * actual CRC). |
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| 52 | * If 0, you must swap the CRC parameter and the result of av_crc |
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| 53 | * if you need the standard representation (can be simplified in |
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| 54 | * most cases to e.g. bswap16): |
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| 55 | * av_bswap32(crc << (32-bits)) |
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| 56 | * @param bits number of bits for the CRC |
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| 57 | * @param poly generator polynomial without the x**bits coefficient, in the |
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| 58 | * representation as specified by le |
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| 59 | * @param ctx_size size of ctx in bytes |
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| 60 | * @return <0 on failure |
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| 61 | */ |
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| 62 | int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size); |
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| 63 | |||
| 64 | /** |
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| 65 | * Get an initialized standard CRC table. |
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| 66 | * @param crc_id ID of a standard CRC |
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| 67 | * @return a pointer to the CRC table or NULL on failure |
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| 68 | */ |
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| 69 | const AVCRC *av_crc_get_table(AVCRCId crc_id); |
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| 70 | |||
| 71 | /** |
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| 72 | * Calculate the CRC of a block. |
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| 73 | * @param crc CRC of previous blocks if any or initial value for CRC |
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| 74 | * @return CRC updated with the data from the given block |
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| 75 | * |
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| 76 | * @see av_crc_init() "le" parameter |
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| 77 | */ |
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| 78 | uint32_t av_crc(const AVCRC *ctx, uint32_t crc, |
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| 79 | const uint8_t *buffer, size_t length) av_pure; |
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| 80 | |||
| 81 | /** |
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| 82 | * @} |
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| 83 | */ |
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| 84 | |||
| 85 | #endif /* AVUTIL_CRC_H */ |