yading@11: /*
yading@11:  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #ifndef AVUTIL_CRC_H
yading@11: #define AVUTIL_CRC_H
yading@11: 
yading@11: #include <stdint.h>
yading@11: #include <stddef.h>
yading@11: #include "attributes.h"
yading@11: 
yading@11: typedef uint32_t AVCRC;
yading@11: 
yading@11: typedef enum {
yading@11:     AV_CRC_8_ATM,
yading@11:     AV_CRC_16_ANSI,
yading@11:     AV_CRC_16_CCITT,
yading@11:     AV_CRC_32_IEEE,
yading@11:     AV_CRC_32_IEEE_LE,  /*< reversed bitorder version of AV_CRC_32_IEEE */
yading@11:     AV_CRC_MAX,         /*< Not part of public API! Do not use outside libavutil. */
yading@11: }AVCRCId;
yading@11: 
yading@11: /**
yading@11:  * Initialize a CRC table.
yading@11:  * @param ctx must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
yading@11:  * @param le If 1, the lowest bit represents the coefficient for the highest
yading@11:  *           exponent of the corresponding polynomial (both for poly and
yading@11:  *           actual CRC).
yading@11:  *           If 0, you must swap the CRC parameter and the result of av_crc
yading@11:  *           if you need the standard representation (can be simplified in
yading@11:  *           most cases to e.g. bswap16):
yading@11:  *           av_bswap32(crc << (32-bits))
yading@11:  * @param bits number of bits for the CRC
yading@11:  * @param poly generator polynomial without the x**bits coefficient, in the
yading@11:  *             representation as specified by le
yading@11:  * @param ctx_size size of ctx in bytes
yading@11:  * @return <0 on failure
yading@11:  */
yading@11: int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size);
yading@11: 
yading@11: /**
yading@11:  * Get an initialized standard CRC table.
yading@11:  * @param crc_id ID of a standard CRC
yading@11:  * @return a pointer to the CRC table or NULL on failure
yading@11:  */
yading@11: const AVCRC *av_crc_get_table(AVCRCId crc_id);
yading@11: 
yading@11: /**
yading@11:  * Calculate the CRC of a block.
yading@11:  * @param crc CRC of previous blocks if any or initial value for CRC
yading@11:  * @return CRC updated with the data from the given block
yading@11:  *
yading@11:  * @see av_crc_init() "le" parameter
yading@11:  */
yading@11: uint32_t av_crc(const AVCRC *ctx, uint32_t crc,
yading@11:                 const uint8_t *buffer, size_t length) av_pure;
yading@11: 
yading@11: #endif /* AVUTIL_CRC_H */