CYMIN	equ	0
CYMAX	equ	199
CXMIN	equ	0
CXMAX	equ	319

clipline PROC NEAR
	;entry: (ax,bx)-(dx,cx)
	;exit: (ax,bx)-(dx,cx) [clipped]
	;(si,bx)-(di,cx)
	mov	cs:clipleft,0
	cmp	bx,cx
	jle	@@2
	mov	si,dx
	mov	di,ax
	xchg	bx,cx
	jmp	@@1
@@2:	mov	si,ax
	mov	di,dx
@@1:	;--- bx<=cx
	cmp	bx,CYMIN
	jge	@@3
	cmp	cx,CYMIN
	jl	@@hid
	mov	ax,di
	sub	ax,si
	mov	bp,CYMIN
	sub	bp,bx
	imul	bp
	mov	bp,cx
	sub	bp,bx
	idiv	bp
	mov	bx,CYMIN
	add	si,ax
@@3:	cmp	cx,CYMAX
	jle	@@4
	cmp	bx,CYMAX
	jg	@@hid
	mov	ax,si
	sub	ax,di
	mov	bp,cx
	sub	bp,CYMAX
	imul	bp
	mov	bp,cx
	sub	bp,bx
	idiv	bp
	mov	cx,CYMAX
	add	di,ax
@@4:	;--- si<=di
	cmp	si,di
	jle	@@5
	xchg	si,di
	xchg	bx,cx
@@5:	cmp	si,CXMIN
	jge	@@6
	cmp	di,CXMIN
	jl	@@hid2
	mov	ax,cx
	sub	ax,bx
	mov	bp,CXMIN
	sub	bp,si
	imul	bp
	mov	bp,di
	sub	bp,si
	idiv	bp
	mov	si,CXMIN
	add	bx,ax
	mov	cs:clipleft,ax
@@6:	cmp	di,CXMAX
	jle	@@7
	cmp	si,CXMAX
	jg	@@hid
	mov	ax,bx
	sub	ax,cx
	mov	bp,di
	sub	bp,CXMAX
	imul	bp
	mov	bp,di
	sub	bp,si
	idiv	bp
	mov	di,CXMAX
	add	cx,ax
@@7:	mov	ax,si
	mov	dx,di
	cmp	bx,cx
	je	@@hid
	clc
	ret
@@hid:	stc
	ret
@@hid2:	;hidden to left
	mov	bp,cx
	sub	bp,bx
	mov	cs:clipleft,bp
	mov	ax,si
	mov	dx,di
	mov	cx,bx
	clc
	ret
clipline ENDP