cxmin:		equ	96
cxmax:		equ	302
cymin:		equ	10
cymax:		equ	188
cbits:	blk.w	1,0
cbits2:	blk.w	1,0
xsav:	blk.w	1,0
ysav:	blk.w	1,0
*dx:	blk.w	1,0
*dy:	blk.w	1,0
*/**//*/*//*//*/*//*//*/*/*//*/*/*/*//*/*/*/*//*//*//*///*/*/
bitcode:clr.l   d4
        cmpi.w  #cxmin,d0
        bge     b1
        or.b    #8,d4
b1:     cmpi.w  #cxmax,d0
        ble     b2
        or.b    #4,d4
b2:     cmpi.w  #cymin,d1
        bge     b3
        or.b    #1,d4
b3:     cmpi.w  #cymax,d1
        ble     b4
        or.b    #2,d4
b4:     move.w  d4,cbits
        rts
*****
bitc2:   clr.l   d5
        cmpi.w  #cxmin,d2
        bge     b5
        or.b    #8,d5
b5:     cmpi.w  #cxmax,d2
        ble     b6
        or.b    #4,d5
b6:     cmpi.w  #cymin,d3
        bge     b7
        or.b    #1,d5
b7:     cmpi.w  #cymax,d3
        ble     b8
        or.b    #2,d5
b8:     move.w  d5,cbits2
        rts
********************************************************
clipit:
	move.w	d7,-(sp)
	bsr     bitcode
        bsr     bitc2
clipit2:or.b    d4,d5
        tst.b   d5
        beq     cliphome        ;finish if
        move.w  cbits,d4
        move.w  d2,xsav
        move.w  d3,ysav
        move.w  cbits2,d5
clip1:  and.b   d4,d5
        tst.b   d5
        bgt     clipb           ;home if line completely out
        move.w  cbits,d4
        move.w  cbits2,d5
        sub.w   d0,d2           ;d1 has dx
        move.w  d2,dx
        sub.w   d1,d3           ;d3 has dy
        move.w  d3,dy
        move.w  xsav,d2
        move.w  ysav,d3
        tst.w   d4
        beq     clip2   	;if x1<xmin
        cmpi.w  #cxmin,d0 	;y1=y1+dy*(xmin-x1)/dx
        bge     c1      
        move.w  #cxmin,d7         ;put xmin in d7
        sub.w   d0,d7
        muls    dy,d7           ;multiply by dy
        divs    dx,d7
        add.w   d1,d7
        move.w  d7,d1
        move.w  #cxmin,d0         ;x1=xmin
        bra     c4
c1:     cmpi.w  #cxmax,d0         ;if x1>xmax
        ble     c2              ;y1=y1+dy*(xmax-x1)/dx
        move.w  #cxmax,d7         ;put xmax in d7
        sub.w   d0,d7
        muls    dy,d7           ;multiply by dy
        divs    dx,d7
        add.w   d1,d7
        move.w  d7,d1
        move.w  #cxmax,d0         ;x1=xmax
        bra     c4
c2:     cmpi.w  #cymin,d1         ;if y1<ymin
        bge     c3
        move.w  #cymin,d7         ;put ymin in d7
        sub.w   d1,d7
        muls    dx,d7           ;multiply by dx
        divs    dy,d7
        add.w   d0,d7
        move.w  d7,d0
        move.w  #cymin,d1         ;y1=ymin
        bra     c4
c3:     cmpi.w  #cymax,d1         ;if y1>xmax
        ble     c4
        move.w  #cymax,d7         ;put ymax in d7
        sub.w   d1,d7
        muls    dx,d7           ;multiply by dy
        divs    dy,d7
        add.w   d0,d7
        move.w  d7,d0
        move.w  #cymax,d1         ;y1=ymax
c4:     bsr     bitcode
        bra     cliploop
******
clip2:  cmpi.w  #cxmin,d2 ;	y1=y1+dy*(xmin-x1)/dx
        bge     cc1     
        move.w  #cxmin,d7         ;put xmin in d7
        sub.w   d2,d7
        muls    dy,d7           ;multiply by dy
        divs    dx,d7
        add.w   d3,d7
        move.w  d7,d3
        move.w  #cxmin,d2         ;x2=xmin
        bra     cc4
cc1:    cmpi.w  #cxmax,d2         ;if x2>xmax
        ble     cc2
        move.w  #cxmax,d7         ;put xmax in d7
        sub.w   d2,d7
        muls    dy,d7           ;multiply by dy
        divs    dx,d7
        add.w   d3,d7
        move.w  d7,d3
        move.w  #cxmax,d2         ;x1=xmax
        bra     cc4
cc2:    cmpi.w  #cymin,d3         ;if y1<ymin
        bge     cc3
        move.w  #cymin,d7         ;put ymin in d7
        sub.w   d3,d7
        muls    dx,d7           ;multiply by dx
        divs    dy,d7
        add.w   d2,d7
        move.w  d7,d2
        move.w  #cymin,d3         ;y1=ymin
        bra     cc4
cc3:    cmpi.w  #cymax,d3         ;if y1>xmax
        ble     cc4
        move.w  #cymax,d7         ;put ymax in d7
        sub.w   d3,d7
        muls    dx,d7           ;multiply by dy
        divs    dy,d7
        add.w   d2,d7
        move.w  d7,d2
        move.w  #cymax,d3         ;y1=ymax
*       bra     cliploop        
cc4:    bsr     bitc2
        bra     cliploop

cliploop:
        bra     clipit2
cliphome:
*        move.l  linepar,a0
        move.w  d0,x1
        move.w  d1,y1
        move.w  d2,x2
        move.w  d3,y2
	bsr	myline
clipb:
	move.w	(sp)+,d7
	rts
*********************************************************
linecolor:
	blk.w	1,0
***********************************************
*	lets plot a fucking line
*	but lets do it fast
*	first some conventions
*	draws line on hiden screen
*	between x1,y1,x2,y2 
***********************************************
myline:
	movem.l	d4-d7/a0,-(sp)
calcdx:
	move.w	x2,d0
	sub.w	x1,d0	;x2-x1
	move.w	d0,dx	;d0 is dx
	bpl	calcdy
	neg	d0
calcdy:
	move.w	y2,d1
	sub.w	y1,d1	;y2-y1	
	move.w	d1,dy	;d6 is dy
	bpl	cmparedxdy
	neg	d1
cmparedxdy:
	cmp.w	d0,d1
	bgt	ymajor	;if dy is greater then ymajor
xmajor:
*	tst.w	dy
*	beq	horizontal	;special case
	tst.w	dx
	bpl	noswapx
	move.w	x2,d0
	move.w	x1,x2
	move.w	d0,x1
	move.w	y2,d0
	move.w	y1,y2
	move.w	d0,y1
	neg	dx
	neg	dy
noswapx:
	move.l	#0,d0
	move.w	dx,d0
	divs	dy,d0
	bmi	xpositive

xnegative:
	move.l	hiden,a0	;screen ad
	move.w	dx,d0
	move.w	d0,d7	;counter is d7
	subq.w	#1,d7
bp:	asr.w	#1,d0	;div by 2
	move.w	d0,d6	;dump is d6
	move.w	x1,d0	;will hold bitpattern
	move.w	d0,d2
	move.w	y1,d1
	lsl.w	#5,d1	;mult y by 128
	adda.w	d1,a0	;add it to screen address
	lsl.w	#2,d1	;mult by 32 makes mult by 160
	add.w	d1,a0	;a0 now has start screen address
	and.w	#$fff0,d0	;mask off last 4 bits gives word across
	lsr.w	#1,d0
	add.w	d0,a0
	moveq	#0,d4
	tst.w	d7
	bmi	specxneg
xmnloop:
	addq.w	#1,d2
	move.w	d2,d3
	and.w	#15,d3
	bne	xmnla
	bsr	putlinein
	moveq	#0,d4
	addq.l	#8,a0
xmnla:	sub.w	#15,d3
	neg	d3
	bset	d3,d4
	sub.w	dy,d6	;sub dy from dump
	bpl	xmn
	add.w	dx,d6
	bsr	putlinein
	adda.l	#160,a0		;moveit to next line
	moveq	#0,d4
xmn:
	dbf	d7,xmnloop
specxneg:
	move.w	d2,d3
	and.w	#15,d3
	sub.w	#15,d3
	neg	d3
	bset	d3,d4
	bsr	putlinein
	movem.l	(sp)+,d4-d7/a0
	rts

putlinein:
	move.w	d4,d5
	eor.w	#$ffff,d5
	and.w	d5,(a0)		;clearout old pixels
	and.w	d5,2(a0)
	and.w	d5,4(a0)
	and.w	d5,6(a0)
	move.w	linecolor,d5
plane1:
	btst	#0,d5
	beq	plane2
	or.w	d4,(a0)
plane2:
	btst	#1,d5
	beq	plane3
	or.w	d4,2(a0)
plane3:
	btst	#2,d5
	beq	plane4
	or.w	d4,4(a0)
plane4:
	btst	#3,d5
	beq	plane5
	or.w	d4,6(a0)
plane5:
	rts



xpositive:
	move.l	hiden,a0	;screen ad
	move.w	dx,d0
	move.w	d0,d7	;counter is d7
	subq.w	#1,d7
	asr.w	#1,d0	;div by 2
	move.w	d0,d6	;dump is d6
	move.w	x1,d0	;will hold bitpattern
	move.w	d0,d2
	move.w	y1,d1
	lsl.w	#5,d1	;mult y by 128
	adda.w	d1,a0	;add it to screen address
	lsl.w	#2,d1	;mult by 32 makes mult by 160
	add.w	d1,a0	;a0 now has start screen address
	and.w	#$fff0,d0	;mask off last 4 bits gives word across
	lsr.w	#1,d0
	add.w	d0,a0
	moveq	#0,d4
xmploop:
	addq.w	#1,d2
	move.w	d2,d3
	and.w	#15,d3
	bne	xmpla
	bsr	putlinein
	moveq	#0,d4
	addq.l	#8,a0
xmpla:	sub.w	#15,d3
	neg	d3
	bset	d3,d4
	add.w	dy,d6	;sub dy from dump
	bpl	xmp
	add.w	dx,d6
	bsr	putlinein
	moveq	#0,d4
	suba.l	#160,a0		;moveit to next line
xmp:
	dbf	d7,xmploop
	move.w	d2,d3
	and.w	#15,d3
	sub.w	#15,d3
	neg	d3
	bset	d3,d4
	bsr	putlinein
	movem.l	(sp)+,d4-d7/a0
	rts

ymajor:
	tst.w	dy
	bpl	noswapy
	move.w	x2,d0
	move.w	x1,x2
	move.w	d0,x1
	move.w	y2,d0
	move.w	y1,y2
	move.w	d0,y1
	neg	dx
	neg	dy
noswapy:
	move.l	#0,d0
	move.w	dy,d0
	divs	dx,d0
	bmi	ypositive
ynegative:
	tst.w	dx
	beq	straightup1	;special case vertical line
	move.l	hiden,a0	;screen ad
	move.w	dy,d0
	move.w	d0,d7	;counter is d7
*	subq.w	#1,d7
	asr.w	#1,d0	;div by 2
	move.w	d0,d6	;dump is d6
	move.w	x1,d0	;will hold bitpattern
	move.w	d0,d3
	move.w	y1,d1
	move.w	d1,d2
	lsl.w	#5,d1	;mult y by 128
	adda.w	d1,a0	;add it to screen address
	lsl.w	#2,d1	;mult by 32 makes mult by 160
	add.w	d1,a0	;a0 now has start screen address
	and.w	#$fff0,d0	;mask off last 4 bits gives word across
	lsr.w	#1,d0
	add.w	d0,a0
	move.w	d3,d0	;x
	moveq	#0,d4
	move.w	d0,d3
	and.w	#15,d3
	move.w	#$8000,d4
	lsr.w	d3,d4
ymnloop:
	bsr	putlinein
	add.w	#160,a0	;y+1
	sub.w	dx,d6	;sub dy from dump
	bpl	ymn
	add.w	dy,d6
	addq.w	#1,d0	;x+1
	move.w	d0,d3
	and.w	#15,d3
	bne	ymnla
	addq.l	#8,a0
ymnla:	move.w	#$8000,d4
	lsr.w	d3,d4
ymn:
	dbf	d7,ymnloop
	movem.l	(sp)+,d4-d7/a0
	rts

ypositive:
	tst.w	dx
	beq	straightup	;special case vertical line
	move.l	hiden,a0	;screen ad
	move.w	dy,d0
	move.w	d0,d7	;counter is d7
	subq.w	#1,d7
	asr.w	#1,d0	;div by 2
	move.w	d0,d6	;dump is d6
	move.w	x1,d0	;will hold bitpattern
	move.w	d0,d3
	move.w	y1,d1
	move.w	d1,d2
	lsl.w	#5,d1	;mult y by 128
	adda.w	d1,a0	;add it to screen address
	lsl.w	#2,d1	;mult by 32 makes mult by 160
	add.w	d1,a0	;a0 now has start screen address
	and.w	#$fff0,d0	;mask off last 4 bits gives word across
	lsr.w	#1,d0
	add.w	d0,a0
	move.w	d3,d0	;x
	moveq	#0,d4
*	move.w	d0,d3
	and.w	#15,d3
	move.w	#$8000,d4
	lsr.w	d3,d4

ymploop:
	bsr	putlinein
	add.w	#160,a0	;y+1
	add.w	dx,d6	;sub dy from dump
	bpl	ymp
	add.w	dy,d6
	subq.w	#1,d0	;x+1
	move.w	d0,d3
	and.w	#15,d3
	cmpi.w	#15,d3
	bne	ympla
	subq.l	#8,a0
ympla:	move.w	#$8000,d4
	lsr.w	d3,d4
ymp:
	dbf	d7,ymploop
	movem.l	(sp)+,d4-d7/a0
	rts

straightup:
	move.l	hiden,a0	;screen ad
	move.w	dy,d7
	move.w	x1,d0	;will hold bitpattern
	move.w	d0,d3
	move.w	y1,d1
	lsl.w	#5,d1	;mult y by 128
	adda.w	d1,a0	;add it to screen address
	lsl.w	#2,d1	;mult by 32 makes mult by 160
	add.w	d1,a0	;a0 now has start screen address
	and.w	#$fff0,d0	;mask off last 4 bits gives word across
	lsr.w	#1,d0
	add.w	d0,a0	;now a0 is ready
	moveq	#0,d4
	and.w	#15,d3
	move.w	#$8000,d4
	lsr.w	d3,d4	;d4 has proper bit pattern
	add.l	#160,a0
stuploop:
	bsr	putlinein
	add.l	#160,a0
	dbf	d7,stuploop
	movem.l	(sp)+,d4-d7/a0
	rts	

straightup1:
	move.l	hiden,a0	;screen ad
	move.w	dy,d7
	move.w	x1,d0	;will hold bitpattern
	move.w	d0,d3
	move.w	y1,d1
	lsl.w	#5,d1	;mult y by 128
	adda.w	d1,a0	;add it to screen address
	lsl.w	#2,d1	;mult by 32 makes mult by 160
	add.w	d1,a0	;a0 now has start screen address
	and.w	#$fff0,d0	;mask off last 4 bits gives word across
	lsr.w	#1,d0
	add.w	d0,a0	;now a0 is ready
	moveq	#0,d4
	and.w	#15,d3
	move.w	#$8000,d4
	lsr.w	d3,d4	;d4 has proper bit pattern
	add.l	#160,a0

stuploop1:
	bsr	putlinein
	sub.l	#160,a0
	dbf	d7,stuploop
	movem.l	(sp)+,d4-d7/a0
	rts	


dump:	blk.w	1,0
gradient:	blk.w	1,0
x1:	blk.w	1,0
x2:	blk.w	1,0
y1:	blk.w	1,0
y2:	blk.w	1,0
dx:	blk.w	1,0
dy:	blk.w	1,0

