XLIB	pointxy

	LIB pixeladdress

; ******************************************************************
;
; Check if pixel at	(x,y) coordinate is	set or not.
;
; Design & programming by Gunther Strube, Copyright (C) InterLogic 1995
;
; (0,0) origin	is defined as the bottom	left	corner.
;
;  in:	hl =	(x,y) coordinate of	pixel to test
; out:	Fz =	0, if pixel is	set,	otherwise	Fz =	1.
;
; registers changed	after return:
;  ..bcdehl/ixiy same
;  af....../.... different
;
.pointxy			push	bc
				push	de
				push	hl
				ld	a,l
				xor	@00111111			; (0,0) is hardware	(0,63)
				ld	l,a

				call	pixeladdress
				ld	b,a
				ld	a,1
				jr	z, test_pixel		; pixel is at bit 0...
.pixel_position	rlca
				djnz	pixel_position
.test_pixel		ex	de,hl
				and	(hl)
				pop	hl
				pop	de
				pop	bc
				ret