lea	Number_A,a0
	lea	Number_B,a1
	movem.l	(a0),d0-d3		; unpack 128-bit number
	add.l	(a1)+,d0
	addx.l	(a1)+,d1
	addx.l	(a1)+,d2
	addx.l	(a1)+,d3
	movem.l	d0-d3,(a0)		; pack 128-bit number