1-Wire CRC: A CLI tool to calculate or verify CRC for device ROM IDs

owcrc.c

/*
	Simply command line tool to calculate CRC
	of device ROM IDs for dallas 1-wire devices
	(or compatible)
*/
#include <stdio.h>
#include <stdint.h>

static uint8_t crcUpdate8(uint8_t crc, uint8_t data) {
	uint8_t j;
	crc = crc ^ data;
	for (j = 0; j < 8; j=j+1) {
		if ((crc & 0x01) != 0) {
			crc = (crc >> 1) ^ 0x8C;
		} else {
			crc = crc >> 1;
		}
	}
	return crc;
}

int main(int argc, char* argv[]) {
	uint8_t data[8];
	unsigned int nextValue;
	uint8_t crc = 0;
	uint8_t i;

	/*
		Command line argument:	7 bytes hexadecimal
	*/
	if((argc != 8) && (argc != 9)) {
		printf("Calculate or validate Dallas 1-wire ROM ID CRC\n");
		printf("Usage:\n");
		printf("\tValidation: %s B0 B1 B2 B3 B4 B5 B6 B7\n", argv[0]);
		printf("\tCalculation: %s B0 B1 B2 B3 B4 B5 B6\n", argv[0]);
		return -1;
	}

	for(i = 1; i < argc; i=i+1) {
		// Read hex value
		if(sscanf(argv[i], "%x ", &nextValue) < 1) {
			printf("Invalid argument\n");
			return -1;
		}

		if(nextValue > 255) {
			printf("Invalid argument %x\n", nextValue);
			return;
		}
		data[i-1] = (uint8_t)nextValue;
		crc = crcUpdate8(crc, data[i-1]);
	}

	if(argc == 8) {
		data[7] = crc;
		for(i = 0; i < 8; i=i+1) {
			if(i != 7) {
				printf("0x%x, ", data[i]);
			} else {
				printf("0x%x\n", data[i]);
			}
		}
	} else if(argc == 9) {
		if(crc == 0) {
			printf("Ok\n");
			return 0;
		} else {
			printf("Failed\n");
			return -1;
		}
	}
}