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source: code/branches/questsystem/src/util/CRC32.cc @ 2258

Last change on this file since 2258 was 1791, checked in by landauf, 16 years ago

added comments to all my classes in util

  • Property svn:eol-style set to native
File size: 1.7 KB
Line 
1/*
2 *   ORXONOX - the hottest 3D action shooter ever to exist
3 *                    > www.orxonox.net <
4 *
5 *
6 *   License notice:
7 *
8 *   This program is free software; you can redistribute it and/or
9 *   modify it under the terms of the GNU General Public License
10 *   as published by the Free Software Foundation; either version 2
11 *   of the License, or (at your option) any later version.
12 *
13 *   This program is distributed in the hope that it will be useful,
14 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
15 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 *   GNU General Public License for more details.
17 *
18 *   You should have received a copy of the GNU General Public License
19 *   along with this program; if not, write to the Free Software
20 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
21 *
22 *   Author:
23 *      ...
24 *   Co-authors:
25 *      ...
26 *
27 */
28
29#include "CRC32.h"
30
31
32void calcCRCBit(uint32_t &crc32, int bit){
33    int hbit;
34
35    hbit=(crc32 & 0x80000000) ? 1 : 0;
36    if (hbit != bit)
37      crc32=(crc32<<1) ^ UTIL_CRC32POLY;
38    else
39      crc32=crc32<<1;
40  }
41
42  uint32_t calcCRC(unsigned char *data, unsigned int dataLength){
43    uint32_t crc32=0;
44    for(unsigned int i=0; i<dataLength; i++){
45      calcCRCBit(crc32, (data[i]&0x1)>>0); // 1st bit
46      calcCRCBit(crc32, (data[i]&0x2)>>1); // 2nd bit
47      calcCRCBit(crc32, (data[i]&0x3)>>2); // 3rd bit
48      calcCRCBit(crc32, (data[i]&0x4)>>3); // 4th bit
49      calcCRCBit(crc32, (data[i]&0x5)>>4); // 5th bit
50      calcCRCBit(crc32, (data[i]&0x6)>>5); // 6th bit
51      calcCRCBit(crc32, (data[i]&0x7)>>6); // 7th bit
52      calcCRCBit(crc32, (data[i]&0x8)>>7); // 8th bit
53    }
54    return crc32;
55  }
56
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