source: code/trunk/src/util/CRC32.cc @ 1767

/*
 *   ORXONOX - the hottest 3D action shooter ever to exist
 *                    > www.orxonox.net <
 *
 *
 *   License notice:
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation; either version 2
 *   of the License, or (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 *   Author:
 *      Fabian 'x3n' Landau
 *   Co-authors:
 *      ...
 *
 */

#include "CRC32.h"


void calcCRCBit(uint32_t &crc32, int bit){
    int hbit;
 
    hbit=(crc32 & 0x80000000) ? 1 : 0;
    if (hbit != bit)
      crc32=(crc32<<1) ^ UTIL_CRC32POLY;
    else
      crc32=crc32<<1;
  }

  uint32_t calcCRC(unsigned char *data, unsigned int dataLength){
    uint32_t crc32=0;
    for(unsigned int i=0; i<dataLength; i++){
      calcCRCBit(crc32, (data[i]&0x1)>>0); // 1st bit
      calcCRCBit(crc32, (data[i]&0x2)>>1); // 2nd bit
      calcCRCBit(crc32, (data[i]&0x3)>>2); // 3rd bit
      calcCRCBit(crc32, (data[i]&0x4)>>3); // 4th bit
      calcCRCBit(crc32, (data[i]&0x5)>>4); // 5th bit
      calcCRCBit(crc32, (data[i]&0x6)>>5); // 6th bit
      calcCRCBit(crc32, (data[i]&0x7)>>6); // 7th bit
      calcCRCBit(crc32, (data[i]&0x8)>>7); // 8th bit
    }
    return crc32;
  }