clr a
	mov r0, a
	mov p2, a
	cpl a

lp1:
	movx @r0, a  ;P2 = 0
	inc p2
	movx @r0, a  ;P2 = 1
	inc p2
	movx @r0, a  ;P2 = 2
	inc p2
	movx @r0, a  ;P2 = 3
	dec r0
	movx @r0, a  ;P2 = 3
	dec p2
	movx @r0, a  ;P2 = 2
	dec p2
	movx @r0, a  ;P2 = 1
	dec p2
	movx @r0, a  ;P2 = 0
	djnz r0, lp1