/*
* cyclic redundancy check 32 bit
* Copyright (C) 1999 Christian Wolff, 2004 Oskar Schirmer
* for Convergence Integrated Media GmbH (http://www.convergence.de)
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <stdint.h>
#include "crc32.h"
uint32_t crc_32_table[256];
// generate the tables of CRC-32 remainders for all possible bytes
void gen_crc32_table() {
register int i,j;
register uint32_t crc32;
for (i=0; i<256; i++) {
crc32=(uint32_t)i << 24;
for (j=0; j<8; j++) {
crc32 = (crc32 << 1) ^ ((crc32 & (1<<31)) ? POLYNOMIAL_32_MSBF : 0);
}
crc_32_table[i]=crc32;
}
}
// update the CRC on the data block one byte at a time
uint32_t update_crc_32_block(uint32_t crc, char *data_block_ptr, int data_block_size)
{
register int i;
for (i=data_block_size; i>0; i--)
crc=update_crc_32(crc, *data_block_ptr++);
return crc;
}
void crc32_calc (char *data,
int size,
char *crc)
{
uint32_t c;
c = CRC_INIT_32;
while (--size >= 0) {
c = update_crc_32 (c,*data++);
}
crc[3] = c; c >>= 8;
crc[2] = c; c >>= 8;
crc[1] = c; c >>= 8;
crc[0] = c;
}
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