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1 | /* -*-c-*- |
2 | * |
3 | * $Id: crc32.h,v 1.1 1998/06/17 23:44:42 mdw Exp $ |
4 | * |
5 | * Calculating cyclic redundancy values (non-cryptographic!) |
6 | * |
7 | * (c) 1998 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
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 |
22 | * GNU General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with mLib; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: crc32.h,v $ |
32 | * Revision 1.1 1998/06/17 23:44:42 mdw |
33 | * Initial revision |
34 | * |
35 | */ |
36 | |
37 | #ifndef CRC32_H |
38 | #define CRC32_h |
39 | |
40 | #ifdef __cplusplus |
41 | extern "C" { |
42 | #endif |
43 | |
44 | /*----- External values ---------------------------------------------------*/ |
45 | |
46 | extern unsigned long crc32_table[256]; |
47 | |
48 | /*----- Macros ------------------------------------------------------------*/ |
49 | |
50 | /* --- @CRC32@ --- * |
51 | * |
52 | * Arguments: @unsigned long result@ = where to put the result |
53 | * @unsigned long crc@ = carryover from previous call, or zero |
54 | * @void *buf@ = pointer to buffer to check |
55 | * @size_t sz@ = size of the buffer |
56 | * |
57 | * Use: A restartable CRC calculator wrapped up in a macro. |
58 | */ |
59 | |
60 | #define CRC32(result, crc, buf, sz) do { \ |
61 | const unsigned char *_p = (const unsigned char *)(buf); \ |
62 | const unsigned char *_l = _p + (sz); \ |
63 | unsigned long _crc = ~(crc) & 0xffffffffu; \ |
64 | \ |
65 | while (_p < _l) \ |
66 | _crc = (_crc >> 8) ^ crc32_table[(*_p++ ^ _crc) & 0xffu]; \ |
67 | (result) = ~_crc & 0xffffffffu; \ |
68 | } while (0) |
69 | |
70 | /*----- Functions provided ------------------------------------------------*/ |
71 | |
72 | /* --- @crc32@ --- * |
73 | * |
74 | * Arguments: @unsigned long crc@ = carryover from previous call, or zero |
75 | * @const void *buf@ = pointer to buffer to check |
76 | * @size_t sz@ = size of the buffer |
77 | * |
78 | * Returns: The CRC updated by the new buffer. |
79 | * |
80 | * Use: A restartable CRC calculator. This is just a function |
81 | * wrapper for the macro version. |
82 | */ |
83 | |
84 | extern unsigned long crc32(unsigned long /*crc*/, |
85 | const void */*buf*/, size_t /*sz*/); |
86 | |
87 | /*----- That's all, folks -------------------------------------------------*/ |
88 | |
89 | #ifdef __cplusplus |
90 | } |
91 | #endif |
92 | |
93 | #endif |