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99 lines
3.0 KiB
99 lines
3.0 KiB
/* |
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* copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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/** |
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* @file |
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* @ingroup lavu_crc32 |
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* Public header for CRC hash function implementation. |
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*/ |
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#ifndef AVUTIL_CRC_H |
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#define AVUTIL_CRC_H |
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#include <stdint.h> |
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#include <stddef.h> |
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#include "attributes.h" |
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/** |
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* @defgroup lavu_crc32 CRC |
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* @ingroup lavu_hash |
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* CRC (Cyclic Redundancy Check) hash function implementation. |
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* |
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* This module supports numerous CRC polynomials, in addition to the most |
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* widely used CRC-32-IEEE. See @ref AVCRCId for a list of available |
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* polynomials. |
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* |
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* @{ |
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*/ |
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typedef uint32_t AVCRC; |
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typedef enum { |
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AV_CRC_8_ATM, |
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AV_CRC_16_ANSI, |
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AV_CRC_16_CCITT, |
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AV_CRC_32_IEEE, |
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AV_CRC_32_IEEE_LE, /*< reversed bitorder version of AV_CRC_32_IEEE */ |
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AV_CRC_16_ANSI_LE, /*< reversed bitorder version of AV_CRC_16_ANSI */ |
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AV_CRC_24_IEEE, |
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AV_CRC_8_EBU, |
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AV_CRC_MAX, /*< Not part of public API! Do not use outside libavutil. */ |
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}AVCRCId; |
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/** |
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* Initialize a CRC table. |
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* @param ctx must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024 |
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* @param le If 1, the lowest bit represents the coefficient for the highest |
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* exponent of the corresponding polynomial (both for poly and |
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* actual CRC). |
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* If 0, you must swap the CRC parameter and the result of av_crc |
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* if you need the standard representation (can be simplified in |
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* most cases to e.g. bswap16): |
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* av_bswap32(crc << (32-bits)) |
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* @param bits number of bits for the CRC |
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* @param poly generator polynomial without the x**bits coefficient, in the |
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* representation as specified by le |
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* @param ctx_size size of ctx in bytes |
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* @return <0 on failure |
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*/ |
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int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size); |
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/** |
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* Get an initialized standard CRC table. |
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* @param crc_id ID of a standard CRC |
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* @return a pointer to the CRC table or NULL on failure |
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*/ |
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const AVCRC *av_crc_get_table(AVCRCId crc_id); |
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/** |
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* Calculate the CRC of a block. |
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* @param crc CRC of previous blocks if any or initial value for CRC |
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* @return CRC updated with the data from the given block |
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* |
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* @see av_crc_init() "le" parameter |
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*/ |
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uint32_t av_crc(const AVCRC *ctx, uint32_t crc, |
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const uint8_t *buffer, size_t length) av_pure; |
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/** |
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* @} |
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*/ |
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#endif /* AVUTIL_CRC_H */
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