3 * $Id: crc32.h,v 1.3 1999/05/06 19:51:35 mdw Exp $
5 * Calculating cyclic redundancy values (non-cryptographic!)
7 * (c) 1998 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
14 * mLib is free software; you can redistribute it and/or modify
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.
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 Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.3 1999/05/06 19:51:35 mdw
34 * Reformatted the LGPL notice a little bit.
36 * Revision 1.2 1999/05/05 18:50:31 mdw
37 * Change licensing conditions to LGPL.
39 * Revision 1.1.1.1 1998/06/17 23:44:42 mdw
40 * Initial version of mLib
51 /*----- External values ---------------------------------------------------*/
53 extern unsigned long crc32_table[256];
55 /*----- Macros ------------------------------------------------------------*/
59 * Arguments: @unsigned long result@ = where to put the result
60 * @unsigned long crc@ = carryover from previous call, or zero
61 * @void *buf@ = pointer to buffer to check
62 * @size_t sz@ = size of the buffer
64 * Use: A restartable CRC calculator wrapped up in a macro.
67 #define CRC32(result, crc, buf, sz) do { \
68 const unsigned char *_p = (const unsigned char *)(buf); \
69 const unsigned char *_l = _p + (sz); \
70 unsigned long _crc = ~(crc) & 0xffffffffu; \
73 _crc = (_crc >> 8) ^ crc32_table[(*_p++ ^ _crc) & 0xffu]; \
74 (result) = ~_crc & 0xffffffffu; \
77 /*----- Functions provided ------------------------------------------------*/
81 * Arguments: @unsigned long crc@ = carryover from previous call, or zero
82 * @const void *buf@ = pointer to buffer to check
83 * @size_t sz@ = size of the buffer
85 * Returns: The CRC updated by the new buffer.
87 * Use: A restartable CRC calculator. This is just a function
88 * wrapper for the macro version.
91 extern unsigned long crc32(unsigned long /*crc*/,
92 const void */*buf*/, size_t /*sz*/);
94 /*----- That's all, folks -------------------------------------------------*/