;;; Authors: MCS-178 gang -- 02/10/2006
;;; 
;;; gcd.s -- find the gcd of two nonnegative integers a and b
;;; 
;;; Registers Used:
;;;   a -- input, output
;;;   b -- input
;;; both a and b may be clobbered

allocate-registers a, b       ; inputs
allocate-registers aremb      ; temporary
allocate-registers loop, bis0 ; labels

	read a
	read b

Lloop:
	li bis0, Lbis0
	jeqz b, bis0
	rem aremb, a, b
	li a, 0
	add a, a, b
	li b, 0
	add b, b, aremb
	li loop, Lloop
	j loop

Lbis0:
	write a
	halt