| /* |
| * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> |
| * |
| * 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. |
| */ |
| |
| #ifndef AVUTIL_CRC_H |
| #define AVUTIL_CRC_H |
| |
| #include <stdint.h> |
| #include <stddef.h> |
| #include "attributes.h" |
| #include "version.h" |
| |
| /** |
| * @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 crc CRC of previous blocks if any or initial value for CRC |
| * @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; |
| |
| /** |
| * @} |
| */ |
| |
| #endif /* AVUTIL_CRC_H */ |
