mov	ax,es:[bx-2]
	xor	ax,8000h
	test	ax,4000h
	jz	@@5
	mov	dl,al
	and	dl,1
	shl	dl,5
	mov	al,dl
@@5:	mov	es:[bx-2],ax
@@7:	pop	ax
	;lightsource
		;push	es
		;push	bx
		;mov	bx,0a000h
		;mov	es,bx
		;mov	bx,ax
		;sar	bx,8
		;add	bx,320
		;inc	byte ptr es:[bx]
		;pop	bx
		;pop	es
	mov	cl,cs:_lightshift
	shrd	ax,dx,cl
	cmp	ax,0
	jge	@@s1
	mov	ax,0
@@s1:	cmp	ax,15
	jle	@@s2
	mov	ax,15
@@s2:	;mov	dx,15
	;sub	dx,ax
	mov	dx,ax
;	mov	ax,es:[bx-2]
;	and	ax,not 15
;	or	ax,dx
;	mov	es:[bx-2],ax
	ret