3 * $Id: crc32.h,v 1.1 1998/06/17 23:44:42 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 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.
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.
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.
29 /*----- Revision history --------------------------------------------------*
32 * Revision 1.1 1998/06/17 23:44:42 mdw
44 /*----- External values ---------------------------------------------------*/
46 extern unsigned long crc32_table[256];
48 /*----- Macros ------------------------------------------------------------*/
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
57 * Use: A restartable CRC calculator wrapped up in a macro.
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; \
66 _crc = (_crc >> 8) ^ crc32_table[(*_p++ ^ _crc) & 0xffu]; \
67 (result) = ~_crc & 0xffffffffu; \
70 /*----- Functions provided ------------------------------------------------*/
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
78 * Returns: The CRC updated by the new buffer.
80 * Use: A restartable CRC calculator. This is just a function
81 * wrapper for the macro version.
84 extern unsigned long crc32(unsigned long /*crc*/,
85 const void */*buf*/, size_t /*sz*/);
87 /*----- That's all, folks -------------------------------------------------*/