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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: crc32.h,v 1.7 2004/04/08 01:36:11 mdw Exp $ |
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4 | * |
5 | * Calculating cyclic redundancy values (non-cryptographic!) |
6 | * |
7 | * (c) 1998 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
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15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
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19 | * mLib is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
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25 | * License along with mLib; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
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28 | */ |
29 | |
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30 | #ifndef MLIB_CRC32_H |
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31 | #define MLIB_CRC32_H |
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32 | |
33 | #ifdef __cplusplus |
34 | extern "C" { |
35 | #endif |
36 | |
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37 | /*----- Header files ------------------------------------------------------*/ |
38 | |
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39 | #ifndef MLIB_BITS_H |
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40 | # include "bits.h" |
41 | #endif |
42 | |
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43 | /*----- External values ---------------------------------------------------*/ |
44 | |
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45 | extern uint32 crc32_table[256]; |
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46 | |
47 | /*----- Macros ------------------------------------------------------------*/ |
48 | |
49 | /* --- @CRC32@ --- * |
50 | * |
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51 | * Arguments: @uint32 result@ = where to put the result |
52 | * @uint32 crc@ = carryover from previous call, or zero |
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53 | * @void *buf@ = pointer to buffer to check |
54 | * @size_t sz@ = size of the buffer |
55 | * |
56 | * Use: A restartable CRC calculator wrapped up in a macro. |
57 | */ |
58 | |
59 | #define CRC32(result, crc, buf, sz) do { \ |
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60 | const octet *_p = (const octet *)(buf); \ |
61 | const octet *_l = _p + (sz); \ |
62 | uint32 _crc = U32(~(crc)); \ |
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63 | \ |
64 | while (_p < _l) \ |
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65 | _crc = (_crc >> 8) ^ crc32_table[U8(*_p++ ^ _crc)]; \ |
66 | (result) = U32(~_crc); \ |
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67 | } while (0) |
68 | |
69 | /*----- Functions provided ------------------------------------------------*/ |
70 | |
71 | /* --- @crc32@ --- * |
72 | * |
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73 | * Arguments: @uint32 crc@ = carryover from previous call, or zero |
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74 | * @const void *buf@ = pointer to buffer to check |
75 | * @size_t sz@ = size of the buffer |
76 | * |
77 | * Returns: The CRC updated by the new buffer. |
78 | * |
79 | * Use: A restartable CRC calculator. This is just a function |
80 | * wrapper for the macro version. |
81 | */ |
82 | |
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83 | extern uint32 crc32(uint32 /*crc*/, const void */*buf*/, size_t /*sz*/); |
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84 | |
85 | /*----- That's all, folks -------------------------------------------------*/ |
86 | |
87 | #ifdef __cplusplus |
88 | } |
89 | #endif |
90 | |
91 | #endif |