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1 | /* -*-c-*- |
2 | * |
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3 | * Calculating cyclic redundancy values (non-cryptographic!) |
4 | * |
5 | * (c) 1998 Straylight/Edgeware |
6 | */ |
7 | |
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8 | /*----- Licensing notice --------------------------------------------------* |
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9 | * |
10 | * This file is part of the mLib utilities library. |
11 | * |
12 | * mLib is free software; you can redistribute it and/or modify |
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13 | * it under the terms of the GNU Library General Public License as |
14 | * published by the Free Software Foundation; either version 2 of the |
15 | * License, or (at your option) any later version. |
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16 | * |
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17 | * mLib is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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20 | * GNU Library General Public License for more details. |
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21 | * |
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22 | * You should have received a copy of the GNU Library General Public |
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23 | * License along with mLib; if not, write to the Free |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
25 | * MA 02111-1307, USA. |
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26 | */ |
27 | |
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28 | #ifndef MLIB_CRC32_H |
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29 | #define MLIB_CRC32_H |
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30 | |
31 | #ifdef __cplusplus |
32 | extern "C" { |
33 | #endif |
34 | |
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35 | /*----- Header files ------------------------------------------------------*/ |
36 | |
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37 | #ifndef MLIB_BITS_H |
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38 | # include "bits.h" |
39 | #endif |
40 | |
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41 | /*----- External values ---------------------------------------------------*/ |
42 | |
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43 | extern const uint32 crc32_table[256]; |
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44 | |
45 | /*----- Macros ------------------------------------------------------------*/ |
46 | |
47 | /* --- @CRC32@ --- * |
48 | * |
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49 | * Arguments: @uint32 result@ = where to put the result |
50 | * @uint32 crc@ = carryover from previous call, or zero |
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51 | * @void *buf@ = pointer to buffer to check |
52 | * @size_t sz@ = size of the buffer |
53 | * |
54 | * Use: A restartable CRC calculator wrapped up in a macro. |
55 | */ |
56 | |
57 | #define CRC32(result, crc, buf, sz) do { \ |
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58 | const octet *_p = (const octet *)(buf); \ |
59 | const octet *_l = _p + (sz); \ |
60 | uint32 _crc = U32(~(crc)); \ |
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61 | \ |
62 | while (_p < _l) \ |
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63 | _crc = (_crc >> 8) ^ crc32_table[U8(*_p++ ^ _crc)]; \ |
64 | (result) = U32(~_crc); \ |
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65 | } while (0) |
66 | |
67 | /*----- Functions provided ------------------------------------------------*/ |
68 | |
69 | /* --- @crc32@ --- * |
70 | * |
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71 | * Arguments: @uint32 crc@ = carryover from previous call, or zero |
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72 | * @const void *buf@ = pointer to buffer to check |
73 | * @size_t sz@ = size of the buffer |
74 | * |
75 | * Returns: The CRC updated by the new buffer. |
76 | * |
77 | * Use: A restartable CRC calculator. This is just a function |
78 | * wrapper for the macro version. |
79 | */ |
80 | |
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81 | extern uint32 crc32(uint32 /*crc*/, const void */*buf*/, size_t /*sz*/); |
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82 | |
83 | /*----- That's all, folks -------------------------------------------------*/ |
84 | |
85 | #ifdef __cplusplus |
86 | } |
87 | #endif |
88 | |
89 | #endif |