crc4.c

Error checking CRC and CRC TABLE GENERATORS in C Language

#include <stdio.h>

const unsigned char tab_crc4[16] = {
0, 3, 6, 5,
12, 15, 10, 9,
11, 8, 13, 14,
7, 4, 1, 2 };

unsigned char crc4(unsigned char buf[])
{
	char k=0, crc=0;

	for(k=0;buf[k]!=NULL;k++)
	{
		crc^=buf[k]>>4;		//PARTE ALTA
		crc=tab_crc4[crc];
		crc^=buf[k]&0xF;	//PARTE BAIXA
		crc=tab_crc4[crc];
	}

	return crc;
}

int main()
{
	unsigned char buf[80];

	printf("DIGITE OS DADOS PARA O CALCULO DO CRC\n");
	scanf("%s", buf);

	printf("\n%X\n", crc4(buf));

	return 0;
}