CRC32 계산

#include <stdio.h>

unsigned int crc32b(unsigned char *message) {
	int i, j;
	unsigned int byte, crc, mask;

	i = 0;
	crc = 0xFFFFFFFF;
	while (message[i] != 0) {
		byte = message[i];            // Get next byte.
		crc = crc ^ byte;
		for (j = 7; j >= 0; j--) {    // Do eight times.
			mask = -(crc & 1);
			crc = (crc >> 1) ^ (0xEDB88320 & mask);
		}
		i = i + 1;
	}
	
	return ~crc;
}

int main () {
	unsigned long crc;
	char in_frame[12];
	
	in_frame[0] = 0x55;
	in_frame[1] = 0xA1;
	in_frame[2] = 0x12;
	in_frame[3] = 0x34;
	in_frame[4] = 0x55;
	in_frame[5] = 0xA1;
	in_frame[6] = 0x12;
	in_frame[7] = 0x34;
	in_frame[8] = 0x55;
	in_frame[9] = 0xA1;
	in_frame[10] = 0x12;
	in_frame[11] = 0x34;
	crc = crc32b(in_frame);
	
	printf("CRC : %lX", crc);

	return 0;
}

CRC On-line 계산기

• www.lammertbies.nl/comm/info/crc-calculation
• crccalc.com/