mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
99 lines
3.0 KiB
99 lines
3.0 KiB
/* |
|
* 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_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 */
|
|
|