Source to ./crc.c
/*
* Cisco router simulation platform.
* Copyright (c) 2006 Christophe Fillot ([email protected])
*
* CRC functions.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <signal.h>
#include <fcntl.h>
#include <assert.h>
#include "utils.h"
#include "crc.h"
#define CRC12_POLY 0x0f01
#define CRC16_POLY 0xa001
#define CRC32_POLY 0xedb88320L
/* CRC tables */
m_uint16_t crc12_array[256],crc16_array[256];
m_uint32_t crc32_array[256];
/* Initialize CRC-12 algorithm */
static void crc12_init(void)
{
m_uint16_t crc,c;
int i,j;
for(i=0;i<256;i++) {
crc = 0;
c = (m_uint16_t)i;
for(j=0;j<8;j++) {
if ((crc ^ c) & 0x0001)
crc = (crc >> 1) ^ CRC12_POLY;
else
crc = crc >> 1;
c = c >> 1;
}
crc12_array[i] = crc;
}
}
/* Initialize CRC-16 algorithm */
static void crc16_init(void)
{
m_uint16_t crc,c;
int i,j;
for(i=0;i<256;i++) {
crc = 0;
c = (m_uint16_t)i;
for(j=0;j<8;j++) {
if ((crc ^ c) & 0x0001)
crc = (crc >> 1) ^ CRC16_POLY;
else
crc = crc >> 1;
c = c >> 1;
}
crc16_array[i] = crc;
}
}
/* Initialize CRC-32 algorithm */
static void crc32_init(void)
{
unsigned long c;
int n, k;
for (n=0;n<256;n++) {
c = (unsigned long) n;
for (k = 0; k < 8; k++) {
if (c & 1)
c = CRC32_POLY ^ (c >> 1);
else
c = c >> 1;
}
crc32_array[n] = c;
}
}
/* Initialize CRC algorithms */
void crc_init(void)
{
crc12_init();
crc16_init();
crc32_init();
}