crc_gen.cpp

该CRC校验仿真完全符合国际标签卡协议ISO/IEC 14443所规定的CRC_A。是一种按字节进行运算的CRC校验法

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#define BYTE unsigned char
#define WORD unsigned short

WORD UpdataCrc(BYTE ch, WORD *lpwCrc)		//以字节为单位进行计算
{
	ch = (ch ^ (BYTE)((*lpwCrc) & 0x00ff));
	ch = (ch ^ (ch<<4));
	*lpwCrc = (*lpwCrc>>8) ^ ((WORD)ch<<8)
			^ ((WORD)ch<<3) ^ ((WORD)ch>>4);
	return(*lpwCrc);
}

void ComputeCrc(BYTE *Data, int Sum, BYTE *TransmitFirst, BYTE *TransmitSecond)
{
	BYTE chBlock;
	WORD wCrc = 0x6363;			//寄存器初始化

	do{
		chBlock = *Data++;
		UpdataCrc(chBlock, &wCrc);
	}while(--Sum);

	*TransmitFirst = (BYTE)(wCrc & 0xff);
	*TransmitSecond=(BYTE)((wCrc>>8) & 0xff);

	return;
}

BYTE BuffCRC_A[10];
BYTE First, Second;
int Byte_sum;
int i;


int main()
{
	printf("CRC_16 reference results ISO/IEC 14443-3\n");
	printf("Crc-16 G(x)=x^16+x^12+x^5+1\n\n");
	printf("Please input the number and the content of raw data:\n");
	scanf("%d", &Byte_sum);
	for(i=0; i<Byte_sum; i++)
		scanf("%02X", &BuffCRC_A[i]);

	printf("CRC_A of [");
	for(i=0; i<Byte_sum; i++)
		printf("%02X", BuffCRC_A[i]);
	ComputeCrc(BuffCRC_A, Byte_sum, &First, &Second);
	printf("] Transmitted:%02X then %02X.\n", First, Second);

	scanf("%d", &i);
	return 0;
}