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crc.h
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1 /*
2  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #ifndef AVUTIL_CRC_H
22 #define AVUTIL_CRC_H
23 
24 #include <stdint.h>
25 #include <stddef.h>
26 #include "attributes.h"
27 #include "version.h"
28 
29 /**
30  * @defgroup lavu_crc32 CRC32
31  * @ingroup lavu_crypto
32  * @{
33  */
34 
35 typedef uint32_t AVCRC;
36 
37 typedef enum {
42  AV_CRC_32_IEEE_LE, /*< reversed bitorder version of AV_CRC_32_IEEE */
43  AV_CRC_16_ANSI_LE, /*< reversed bitorder version of AV_CRC_16_ANSI */
44 #if FF_API_CRC_BIG_TABLE
46 #else
48 #endif /* FF_API_CRC_BIG_TABLE */
49  AV_CRC_MAX, /*< Not part of public API! Do not use outside libavutil. */
50 }AVCRCId;
51 
52 /**
53  * Initialize a CRC table.
54  * @param ctx must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
55  * @param le If 1, the lowest bit represents the coefficient for the highest
56  * exponent of the corresponding polynomial (both for poly and
57  * actual CRC).
58  * If 0, you must swap the CRC parameter and the result of av_crc
59  * if you need the standard representation (can be simplified in
60  * most cases to e.g. bswap16):
61  * av_bswap32(crc << (32-bits))
62  * @param bits number of bits for the CRC
63  * @param poly generator polynomial without the x**bits coefficient, in the
64  * representation as specified by le
65  * @param ctx_size size of ctx in bytes
66  * @return <0 on failure
67  */
68 int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size);
69 
70 /**
71  * Get an initialized standard CRC table.
72  * @param crc_id ID of a standard CRC
73  * @return a pointer to the CRC table or NULL on failure
74  */
75 const AVCRC *av_crc_get_table(AVCRCId crc_id);
76 
77 /**
78  * Calculate the CRC of a block.
79  * @param crc CRC of previous blocks if any or initial value for CRC
80  * @return CRC updated with the data from the given block
81  *
82  * @see av_crc_init() "le" parameter
83  */
84 uint32_t av_crc(const AVCRC *ctx, uint32_t crc,
85  const uint8_t *buffer, size_t length) av_pure;
86 
87 /**
88  * @}
89  */
90 
91 #endif /* AVUTIL_CRC_H */
uint32_t poly
Definition: crc.c:297
#define av_pure
Definition: attributes.h:70
AVFormatContext * ctx
Definition: movenc-test.c:48
Macro definitions for various function/variable attributes.
uint8_t bits
Definition: crc.c:296
uint8_t
int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size)
Initialize a CRC table.
Definition: crc.c:310
AVCRCId
Definition: crc.h:37
GLsizei GLsizei * length
Definition: opengl_enc.c:115
Libavutil version macros.
uint32_t av_crc(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length) av_pure
Calculate the CRC of a block.
Definition: crc.c:357
uint8_t le
Definition: crc.c:295
const AVCRC * av_crc_get_table(AVCRCId crc_id)
Get an initialized standard CRC table.
Definition: crc.c:343
Definition: crc.h:49
uint32_t AVCRC
Definition: crc.h:35
GLuint buffer
Definition: opengl_enc.c:102