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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: crc32.h,v 1.2 1999/05/05 18:50:31 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 |
25 | * License along with mLib; if not, write to the Free Software |
26 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: crc32.h,v $ |
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32 | * Revision 1.2 1999/05/05 18:50:31 mdw |
33 | * Change licensing conditions to LGPL. |
34 | * |
35 | * Revision 1.1.1.1 1998/06/17 23:44:42 mdw |
36 | * Initial version of mLib |
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37 | * |
38 | */ |
39 | |
40 | #ifndef CRC32_H |
41 | #define CRC32_h |
42 | |
43 | #ifdef __cplusplus |
44 | extern "C" { |
45 | #endif |
46 | |
47 | /*----- External values ---------------------------------------------------*/ |
48 | |
49 | extern unsigned long crc32_table[256]; |
50 | |
51 | /*----- Macros ------------------------------------------------------------*/ |
52 | |
53 | /* --- @CRC32@ --- * |
54 | * |
55 | * Arguments: @unsigned long result@ = where to put the result |
56 | * @unsigned long crc@ = carryover from previous call, or zero |
57 | * @void *buf@ = pointer to buffer to check |
58 | * @size_t sz@ = size of the buffer |
59 | * |
60 | * Use: A restartable CRC calculator wrapped up in a macro. |
61 | */ |
62 | |
63 | #define CRC32(result, crc, buf, sz) do { \ |
64 | const unsigned char *_p = (const unsigned char *)(buf); \ |
65 | const unsigned char *_l = _p + (sz); \ |
66 | unsigned long _crc = ~(crc) & 0xffffffffu; \ |
67 | \ |
68 | while (_p < _l) \ |
69 | _crc = (_crc >> 8) ^ crc32_table[(*_p++ ^ _crc) & 0xffu]; \ |
70 | (result) = ~_crc & 0xffffffffu; \ |
71 | } while (0) |
72 | |
73 | /*----- Functions provided ------------------------------------------------*/ |
74 | |
75 | /* --- @crc32@ --- * |
76 | * |
77 | * Arguments: @unsigned long crc@ = carryover from previous call, or zero |
78 | * @const void *buf@ = pointer to buffer to check |
79 | * @size_t sz@ = size of the buffer |
80 | * |
81 | * Returns: The CRC updated by the new buffer. |
82 | * |
83 | * Use: A restartable CRC calculator. This is just a function |
84 | * wrapper for the macro version. |
85 | */ |
86 | |
87 | extern unsigned long crc32(unsigned long /*crc*/, |
88 | const void */*buf*/, size_t /*sz*/); |
89 | |
90 | /*----- That's all, folks -------------------------------------------------*/ |
91 | |
92 | #ifdef __cplusplus |
93 | } |
94 | #endif |
95 | |
96 | #endif |