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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: crc32.h,v 1.6 2000/07/02 22:20:42 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 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: crc32.h,v $ |
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33 | * Revision 1.6 2000/07/02 22:20:42 mdw |
34 | * Fix constant name. |
35 | * |
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36 | * Revision 1.5 1999/12/10 23:42:04 mdw |
37 | * Change header file guard names. |
38 | * |
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39 | * Revision 1.4 1999/06/01 09:47:22 mdw |
40 | * Make the return type of `crc32' a `uint32' now that we have `bits.h'. |
41 | * |
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42 | * Revision 1.3 1999/05/06 19:51:35 mdw |
43 | * Reformatted the LGPL notice a little bit. |
44 | * |
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45 | * Revision 1.2 1999/05/05 18:50:31 mdw |
46 | * Change licensing conditions to LGPL. |
47 | * |
48 | * Revision 1.1.1.1 1998/06/17 23:44:42 mdw |
49 | * Initial version of mLib |
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50 | * |
51 | */ |
52 | |
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53 | #ifndef MLIB_CRC32_H |
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54 | #define MLIB_CRC32_H |
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55 | |
56 | #ifdef __cplusplus |
57 | extern "C" { |
58 | #endif |
59 | |
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60 | /*----- Header files ------------------------------------------------------*/ |
61 | |
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62 | #ifndef MLIB_BITS_H |
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63 | # include "bits.h" |
64 | #endif |
65 | |
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66 | /*----- External values ---------------------------------------------------*/ |
67 | |
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68 | extern uint32 crc32_table[256]; |
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69 | |
70 | /*----- Macros ------------------------------------------------------------*/ |
71 | |
72 | /* --- @CRC32@ --- * |
73 | * |
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74 | * Arguments: @uint32 result@ = where to put the result |
75 | * @uint32 crc@ = carryover from previous call, or zero |
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76 | * @void *buf@ = pointer to buffer to check |
77 | * @size_t sz@ = size of the buffer |
78 | * |
79 | * Use: A restartable CRC calculator wrapped up in a macro. |
80 | */ |
81 | |
82 | #define CRC32(result, crc, buf, sz) do { \ |
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83 | const octet *_p = (const octet *)(buf); \ |
84 | const octet *_l = _p + (sz); \ |
85 | uint32 _crc = U32(~(crc)); \ |
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86 | \ |
87 | while (_p < _l) \ |
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88 | _crc = (_crc >> 8) ^ crc32_table[U8(*_p++ ^ _crc)]; \ |
89 | (result) = U32(~_crc); \ |
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90 | } while (0) |
91 | |
92 | /*----- Functions provided ------------------------------------------------*/ |
93 | |
94 | /* --- @crc32@ --- * |
95 | * |
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96 | * Arguments: @uint32 crc@ = carryover from previous call, or zero |
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97 | * @const void *buf@ = pointer to buffer to check |
98 | * @size_t sz@ = size of the buffer |
99 | * |
100 | * Returns: The CRC updated by the new buffer. |
101 | * |
102 | * Use: A restartable CRC calculator. This is just a function |
103 | * wrapper for the macro version. |
104 | */ |
105 | |
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106 | extern uint32 crc32(uint32 /*crc*/, const void */*buf*/, size_t /*sz*/); |
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107 | |
108 | /*----- That's all, folks -------------------------------------------------*/ |
109 | |
110 | #ifdef __cplusplus |
111 | } |
112 | #endif |
113 | |
114 | #endif |