/******************************************************************************
 * Jonathan Sawyer
 * jonmsawyer AT gmail DOT com
 * Oct. 9, 2007
 * Arch: Motorola 68HC11 Micro-controller
 * Language: C
 *
 * This calculates the greatest common divisor between two 8-bit unsigned
 * integers using Euclid's algorithm.
 */

/* mod
 * a: takes an 8-bit unsigned integer
 * b: takes an 8-bit unsigned integer
 * returns: an unsigned 8-bit integer that is the remainder of division between
 *          a and b: a / b.
 */
unsigned int mod (unsigned int a, unsigned int b) {
	if (a < b) return a;
	
	if (a == b) return 0;
	
	while (a >= b) {
		a -= b;
	}
	
	return a;
}

/* gcd
 * Computes the greatest common divisor of two unsigned integers by Euclid's
 * algorithm.
 * m: 8-bit unsigned integer (non-negative -- this is important)
 * n: 8-bit unsigned integer (non-negative -- this is important)
 * returns: greatest common divisor of m and n.
 */
int gcd (unsigned int m, unsigned int n) {
	unsigned int r;
	while (n > 0) {
		r = mod(m, n);
		m = n;
		n = r;
	}
	return m;
}

int main() {
	unsigned int a = 600;
	unsigned int b = 17;
	unsigned int c = 0;
	
	c = gcd(a, b);
	
	while (1) { ; }
	return 0;
}