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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 | ||
28 | /** | |
29 | * @defgroup lavu_crc32 CRC32 | |
30 | * @ingroup lavu_crypto | |
31 | * @{ | |
32 | */ | |
33 | ||
34 | typedef uint32_t AVCRC; | |
35 | ||
36 | typedef enum { | |
37 | AV_CRC_8_ATM, | |
38 | AV_CRC_16_ANSI, | |
39 | AV_CRC_16_CCITT, | |
40 | AV_CRC_32_IEEE, | |
41 | AV_CRC_32_IEEE_LE, /*< reversed bitorder version of AV_CRC_32_IEEE */ | |
42 | AV_CRC_16_ANSI_LE, /*< reversed bitorder version of AV_CRC_16_ANSI */ | |
43 | AV_CRC_24_IEEE = 12, | |
44 | AV_CRC_MAX, /*< Not part of public API! Do not use outside libavutil. */ | |
45 | }AVCRCId; | |
46 | ||
47 | /** | |
48 | * Initialize a CRC table. | |
49 | * @param ctx must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024 | |
50 | * @param le If 1, the lowest bit represents the coefficient for the highest | |
51 | * exponent of the corresponding polynomial (both for poly and | |
52 | * actual CRC). | |
53 | * If 0, you must swap the CRC parameter and the result of av_crc | |
54 | * if you need the standard representation (can be simplified in | |
55 | * most cases to e.g. bswap16): | |
56 | * av_bswap32(crc << (32-bits)) | |
57 | * @param bits number of bits for the CRC | |
58 | * @param poly generator polynomial without the x**bits coefficient, in the | |
59 | * representation as specified by le | |
60 | * @param ctx_size size of ctx in bytes | |
61 | * @return <0 on failure | |
62 | */ | |
63 | int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size); | |
64 | ||
65 | /** | |
66 | * Get an initialized standard CRC table. | |
67 | * @param crc_id ID of a standard CRC | |
68 | * @return a pointer to the CRC table or NULL on failure | |
69 | */ | |
70 | const AVCRC *av_crc_get_table(AVCRCId crc_id); | |
71 | ||
72 | /** | |
73 | * Calculate the CRC of a block. | |
74 | * @param crc CRC of previous blocks if any or initial value for CRC | |
75 | * @return CRC updated with the data from the given block | |
76 | * | |
77 | * @see av_crc_init() "le" parameter | |
78 | */ | |
79 | uint32_t av_crc(const AVCRC *ctx, uint32_t crc, | |
80 | const uint8_t *buffer, size_t length) av_pure; | |
81 | ||
82 | /** | |
83 | * @} | |
84 | */ | |
85 | ||
86 | #endif /* AVUTIL_CRC_H */ |