;; Greatest Common Divisor
;; Problem 8.3
;; CS 312
;; Adam Smyth


	INCLUDE	PCMAC.INC 

        .MODEL  SMALL

        .CODE
	PUBLIC	FindGCD
FindGCD PROC
		;; Find the GCD of bx and cx
	cmp	cx, 0
	jne	out2
	mov	ax, bx
	ret
Out2:
	cmp	bx, 0
	jne	out3
	mov	ax, cx
	ret
Out3:
	cmp	bx, -32768
	jne	Out4
	cmp	cx, -32768
	jne	Out5
	mov	ax, -32768
	ret
Out5:
	push	bx
	push	cx
	mov	bx, 16384
	jmp	while1

Out4:	
	push	bx
	push	cx

	cmp	bx, 0
	jnl	While1
	neg	bx


while1:
	cmp	bx, cx
	je	out1
	jnl	else1
	sub	cx, bx
	jmp	while1
else1:
	sub	bx, cx
	jmp	while1
out1:
	mov	ax, cx	; Return GCD in Ax register
	pop	cx
	pop	bx

	ret

FindGCD ENDP

        END