3 * $Id: crc32.h,v 1.5 1999/12/10 23:42:04 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 1.5 1999/12/10 23:42:04 mdw
34 * Change header file guard names.
36 * Revision 1.4 1999/06/01 09:47:22 mdw
37 * Make the return type of `crc32' a `uint32' now that we have `bits.h'.
39 * Revision 1.3 1999/05/06 19:51:35 mdw
40 * Reformatted the LGPL notice a little bit.
42 * Revision 1.2 1999/05/05 18:50:31 mdw
43 * Change licensing conditions to LGPL.
45 * Revision 1.1.1.1 1998/06/17 23:44:42 mdw
46 * Initial version of mLib
57 /*----- Header files ------------------------------------------------------*/
63 /*----- External values ---------------------------------------------------*/
65 extern uint32 crc32_table[256];
67 /*----- Macros ------------------------------------------------------------*/
71 * Arguments: @uint32 result@ = where to put the result
72 * @uint32 crc@ = carryover from previous call, or zero
73 * @void *buf@ = pointer to buffer to check
74 * @size_t sz@ = size of the buffer
76 * Use: A restartable CRC calculator wrapped up in a macro.
79 #define CRC32(result, crc, buf, sz) do { \
80 const octet *_p = (const octet *)(buf); \
81 const octet *_l = _p + (sz); \
82 uint32 _crc = U32(~(crc)); \
85 _crc = (_crc >> 8) ^ crc32_table[U8(*_p++ ^ _crc)]; \
86 (result) = U32(~_crc); \
89 /*----- Functions provided ------------------------------------------------*/
93 * Arguments: @uint32 crc@ = carryover from previous call, or zero
94 * @const void *buf@ = pointer to buffer to check
95 * @size_t sz@ = size of the buffer
97 * Returns: The CRC updated by the new buffer.
99 * Use: A restartable CRC calculator. This is just a function
100 * wrapper for the macro version.
103 extern uint32 crc32(uint32 /*crc*/, const void */*buf*/, size_t /*sz*/);
105 /*----- That's all, folks -------------------------------------------------*/