SRI512 ISO 14443 Type B CRC calculation
Doc ID 13263 Rev 5 43/47
Appendix A ISO 14443 Type B CRC calculation
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#define BYTE unsigned char
#define USHORT unsigned short
unsigned short UpdateCrc(BYTE ch, USHORT *lpwCrc)
{
ch = (ch^(BYTE)((*lpwCrc) & 0x00FF));
ch = (ch^(ch<<4));
*lpwCrc = (*lpwCrc >> 8)^((USHORT)ch <<
8)^((USHORT)ch<<3)^((USHORT)ch>>4);
return(*lpwCrc);
}
void ComputeCrc(char *Data, int Length, BYTE *TransmitFirst, BYTE
*TransmitSecond)
{
BYTE chBlock; USHORTt wCrc;
wCrc = 0xFFFF; // ISO 3309
do
{
chBlock = *Data++;
UpdateCrc(chBlock, &wCrc);
} while (--Length);
wCrc = ~wCrc; // ISO 3309
*TransmitFirst = (BYTE) (wCrc & 0xFF);
*TransmitSecond = (BYTE) ((wCrc >> 8) & 0xFF);
return;
}
int main(void)
{
BYTE BuffCRC_B[10] = {0x0A, 0x12, 0x34, 0x56}, First, Second, i;
printf("Crc-16 G(x) = x^16 + x^12 + x^5 + 1”);
printf("CRC_B of [ ");
for(i=0; i<4; i++)
printf("%02X ",BuffCRC_B[i]);
ComputeCrc(BuffCRC_B, 4, &First, &Second);
printf("] Transmitted: %02X then %02X.”, First, Second);
return(0);
