; langton's ant ------- [

		lxi	s,16384	; stack
		lxi	h,0x707	; xy
		push h
		
ant1:	lxi	h,16382	; fetch x+y*16
		push h		; ( we'll need this later )
		mov	a,m
		add	a
		add	a
		add	a
		add	a
		inx	h
		add m
		inx h		; now points to start of screen
		
		mov	e,a
		mov	d,l		; d = 0
		dad d		
		dad d		; hl += 2*de
		
		lxi	d,dlist	
		call draw	; draw ant, toggle border, erase ant

		; turn left/right
		mov a,m
		ani	2
		dcr	a
		add	c
		;;ani 3
		mov c,a
		
		; move forward
		pop	h		; hl = 16382
		ani	1		; bit 0 = modify x or y?
		add	l
		mov	l,a
		mov	a,c
		ani	2		; bit 1 = add 1 or subtract 1?
		dcr	a
		add	m
		ani	15
		mov	m,a
		
		jmp	ant1

; draw ant at hl
draw:	ldax d
		xra	m
		mov m,a
		inx	h
		ldax d
		xra	m
		mov m,a
		dcx	h
; if ant's been erased, we're done
		ani	0x44
		rz
		inx d 
; pause
pause1:	hlt
		jmp	draw

; display-list

dlist:	db	0x44	; draw ant
		db	0x33	; toggle box
		db	0x44	; erase ant
		
; ---------- ] ant