chiark / gitweb /
Test universal hashing and fix bugs.
[mLib] / crc32.h
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0875b58f 1/* -*-c-*-
2 *
573c5b46 3 * $Id: crc32.h,v 1.6 2000/07/02 22:20:42 mdw Exp $
0875b58f 4 *
5 * Calculating cyclic redundancy values (non-cryptographic!)
6 *
7 * (c) 1998 Straylight/Edgeware
8 */
9
c846879c 10/*----- Licensing notice --------------------------------------------------*
0875b58f 11 *
12 * This file is part of the mLib utilities library.
13 *
14 * mLib is free software; you can redistribute it and/or modify
c846879c 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 *
0875b58f 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
c846879c 22 * GNU Library General Public License for more details.
23 *
24 * You should have received a copy of the GNU Library General Public
0bd98442 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.
0875b58f 28 */
29
30/*----- Revision history --------------------------------------------------*
31 *
32 * $Log: crc32.h,v $
573c5b46 33 * Revision 1.6 2000/07/02 22:20:42 mdw
34 * Fix constant name.
35 *
c6e0eaf0 36 * Revision 1.5 1999/12/10 23:42:04 mdw
37 * Change header file guard names.
38 *
7b4b46a7 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 *
0bd98442 42 * Revision 1.3 1999/05/06 19:51:35 mdw
43 * Reformatted the LGPL notice a little bit.
44 *
c846879c 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
0875b58f 50 *
51 */
52
c6e0eaf0 53#ifndef MLIB_CRC32_H
573c5b46 54#define MLIB_CRC32_H
0875b58f 55
56#ifdef __cplusplus
57 extern "C" {
58#endif
59
7b4b46a7 60/*----- Header files ------------------------------------------------------*/
61
c6e0eaf0 62#ifndef MLIB_BITS_H
7b4b46a7 63# include "bits.h"
64#endif
65
0875b58f 66/*----- External values ---------------------------------------------------*/
67
7b4b46a7 68extern uint32 crc32_table[256];
0875b58f 69
70/*----- Macros ------------------------------------------------------------*/
71
72/* --- @CRC32@ --- *
73 *
7b4b46a7 74 * Arguments: @uint32 result@ = where to put the result
75 * @uint32 crc@ = carryover from previous call, or zero
0875b58f 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 { \
7b4b46a7 83 const octet *_p = (const octet *)(buf); \
84 const octet *_l = _p + (sz); \
85 uint32 _crc = U32(~(crc)); \
0875b58f 86 \
87 while (_p < _l) \
7b4b46a7 88 _crc = (_crc >> 8) ^ crc32_table[U8(*_p++ ^ _crc)]; \
89 (result) = U32(~_crc); \
0875b58f 90} while (0)
91
92/*----- Functions provided ------------------------------------------------*/
93
94/* --- @crc32@ --- *
95 *
7b4b46a7 96 * Arguments: @uint32 crc@ = carryover from previous call, or zero
0875b58f 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
7b4b46a7 106extern uint32 crc32(uint32 /*crc*/, const void */*buf*/, size_t /*sz*/);
0875b58f 107
108/*----- That's all, folks -------------------------------------------------*/
109
110#ifdef __cplusplus
111 }
112#endif
113
114#endif