| /* | |
| * copyright (c) 2006 Michael Niedermayer <[email protected]> | |
| * | |
| * 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 | |
| */ | |
| /** | |
| * @file | |
| * @ingroup lavu_crc32 | |
| * Public header for CRC hash function implementation. | |
| */ | |
| /** | |
| * @defgroup lavu_crc32 CRC | |
| * @ingroup lavu_hash | |
| * CRC (Cyclic Redundancy Check) hash function implementation. | |
| * | |
| * This module supports numerous CRC polynomials, in addition to the most | |
| * widely used CRC-32-IEEE. See @ref AVCRCId for a list of available | |
| * polynomials. | |
| * | |
| * @{ | |
| */ | |
| 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_16_ANSI_LE, /*< reversed bitorder version of AV_CRC_16_ANSI */ | |
| AV_CRC_24_IEEE, | |
| AV_CRC_8_EBU, | |
| 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 ctx initialized AVCRC array (see av_crc_init()) | |
| * @param crc CRC of previous blocks if any or initial value for CRC | |
| * @param buffer buffer whose CRC to calculate | |
| * @param length length of the buffer | |
| * @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; | |
| /** | |
| * @} | |
| */ | |