Eeems: Fixed formatting errors

2010-07-31T04:49:29Z

Fixed formatting errors

Galandros: fix

2010-05-16T13:53:19Z

fix

Galandros: created

2010-05-16T13:52:00Z

created

New page

[[Category:Z80 Routines:Graphic|LineDraw]]
[[Category:Z80 Routines|LineDraw]]

== Code ==

These routines are the best line draws routines around for z80.

=== Small (and fast for its size) ===

<nowiki>
; Small and quite fast
; by Patai Gergely, thanks
DrawLineCompact ; This routine draws an unclipped line on an IX-pointed screen from (d,e) to (h,l)
ld a,h ; Calculating delta X and swapping points if negative
sub d ; (Lines are always drawn from left to right)
jp nc,DL_okaydx
ex de,hl
neg
DL_okaydx:
push af ; Saving DX (it will be popped into DE below)
ld b,0 ; Calculating the position of the first pixel to be drawn
ld c,d ; IX+=D/8+E*12 (actually E*4+E*4+E*4)
srl c
srl c
srl c
add ix,bc
ld c,e
sla c
sla c
add ix,bc
add ix,bc
add ix,bc
ld a,d ; Calculating the starting pixel mask
ld c,$80
and 7
jp z,DL_okaymask
DL_calcmask:
srl c
dec a
jp nz,DL_calcmask
DL_okaymask:
ld a,l ; Calculating delta Y and negating the Y increment if necessary
sub e ; This is the last instruction for which we need the original data
ld hl,12
jp nc,DL_okaydy
ld hl,-12
neg
DL_okaydy:
pop de ; Recalling DX
ld e,a ; D=DX, E=DY
cp d
jp c,DL_horizontal ; Line is rather horizontal than vertical
ld (DL_VLinc+1),hl ; Modifying y increment
push ix ; Loading IX to HL for speed; we don't need the old value of HL any more
pop hl
ld b,e ; Pixel counter
inc b
srl a ; Setting up gradient counter (A=E/2)
ld (DL_HLinc+1),sp ; Backing up SP to a safe place
di ; Interrupts are undesirable when we play around with SP :)
DL_VLinc:
ld sp,0 ; This value is replaced by +/- 12
DL_Vloop:
ex af,af' ; Saving A to alternative register
ld a,(hl)
or c ; Writing pixel to current position
ld (hl),a
ex af,af' ; Recalling A (faster than push-pop, and there's no need for SP)
add hl,sp
sub d ; Handling gradient
jp nc,DL_VnoSideStep
rrc c ; Rotating mask
jp nc,DL_VnoByte ; Handling byte boundary
inc hl
DL_VnoByte:
add a,e
DL_VnoSideStep:
djnz DL_Vloop
ld sp,(DL_HLinc+1)
ret
DL_horizontal:
ld (DL_HLinc+1),hl ; Modifying y increment
push ix ; Loading IX to HL for speed; we don't need the old value of HL any more
pop hl
ld b,d ; Pixel counter
inc b
ld a,d ; Setting up gradient counter
srl a
ld (DL_VLinc+1),sp ; Backing up SP to a safe place
di ; Interrupts again...
DL_HLinc:
ld sp,0 ; This value is replaced by +/- 12
DL_Hloop:
ex af,af' ; Saving A to alternative register
ld a,(hl)
or c ; Writing pixel to current position
ld (hl),a
ex af,af' ; Recalling A
rrc c ; Rotating mask
jp nc,DL_HnoByte ; Handling byte boundary
inc hl
DL_HnoByte:
sub e ; Handling gradient
jp nc,DL_HnoSideStep
add hl,sp
add a,d
DL_HnoSideStep:
djnz DL_Hloop
ld sp,(DL_VLinc+1)
ret
</nowiki>

=== Fast Version ===

;Fast line routine, only sets pixels
;(d,e),(h,l) = (x1,y1),(x2,y2)
;NO clipping
;James Montelongo
FastLine:
ld a,h
cp d
jp nc,noswapx
ex de,hl
noswapx:

ld a,h
sub d
jp nc,posx
neg
posx:
ld b,a
ld a,l
sub e
jp nc,posy
neg
posY:
ld c,a
ld a,l
ld hl,-12
cp e
jp c,lineup
ld hl,12
lineup:
ld ix,xbit
ld a,b
cp c
jp nc,xline
ld b,c
ld c,a
ld ix,ybit
xline:
push hl
ld a,d
ld d,0
ld h,d
sla e
sla e
ld l,e
add hl,de
add hl,de
ld e,a
and %00000111
srl e
srl e
srl e
add hl,de
ld de,gbuf
add hl,de
add a,a
ld e,a
ld d,0
add ix,de
ld e,(ix)
ld d,(ix+1)
push hl
pop ix
ex de,hl
pop de
push hl
ld h,b
ld l,c
ld a,h
srl a
inc b
ret

Xbit:
.dw drawX0,drawX1,drawX2,drawX3
.dw drawX4,drawX5,drawX6,drawX7
Ybit:
.dw drawY0,drawY1,drawY2,drawY3
.dw drawY4,drawY5,drawY6,drawY7

DrawX0:
set 7,(ix)
add a,c
cp h
jp c,$+3+2+1
add ix,de
sub h
djnz DrawX1
ret
DrawX1:
set 6,(ix)
add a,c
cp h
jp c,$+3+2+1
add ix,de
sub h
djnz DrawX2
ret
DrawX2:
set 5,(ix)
add a,c
cp h
jp c,$+3+2+1
add ix,de
sub h
djnz DrawX3
ret
DrawX3:
set 4,(ix)
add a,c
cp h
jp c,$+3+2+1
add ix,de
sub h
djnz DrawX4
ret
DrawX4:
set 3,(ix)
add a,c
cp h
jp c,$+3+2+1
add ix,de
sub h
djnz DrawX5
ret
DrawX5:
set 2,(ix)
add a,c
cp h
jp c,$+3+2+1
add ix,de
sub h
djnz DrawX6
ret
DrawX6:
set 1,(ix)
add a,c
cp h
jp c,$+3+2+1
add ix,de
sub h
djnz DrawX7
ret
DrawX7:
set 0,(ix)
inc ix
add a,c
cp h
jp c,$+3+2+1
add ix,de
sub h
djnz DrawX0
ret

DrawY0_:
inc ix
sub h
dec b
ret z
DrawY0:
set 7,(ix)
add ix,de
add a,l
cp h
jp nc,DrawY1_
djnz DrawY0
ret
DrawY1_:
sub h
dec b
ret z
DrawY1:
set 6,(ix)
add ix,de
add a,l
cp h
jp nc,DrawY2_
djnz DrawY1
ret
DrawY2_:
sub h
dec b
ret z
DrawY2:
set 5,(ix)
add ix,de
add a,l
cp h
jp nc,DrawY3_
djnz DrawY2
ret
DrawY3_:
sub h
dec b
ret z
DrawY3:
set 4,(ix)
add ix,de
add a,l
cp h
jp nc,DrawY4_
djnz DrawY3
ret
DrawY4_:
sub h
dec b
ret z
DrawY4:
set 3,(ix)
add ix,de
add a,l
cp h
jp nc,DrawY5_
djnz DrawY4
ret
DrawY5_:
sub h
dec b
ret z
DrawY5:
set 2,(ix)
add ix,de
add a,l
cp h
jp nc,DrawY6_
djnz DrawY5
ret
DrawY6_:
sub h
dec b
ret z
DrawY6:
set 1,(ix)
add ix,de
add a,l
cp h
jp nc,DrawY7_
djnz DrawY6
ret
DrawY7_:
sub h
dec b
ret z
DrawY7:
set 0,(ix)
add ix,de
add a,l
cp h
jp nc,DrawY0_
djnz DrawY7
ret

=== Special case of vertical lines ===

=== Special case of horizontal lines ===

== Examples ==

For the compact version.
<nowiki>
ld hl,plotsscreen
call ClearScreen
ld de,$0000 ; Hint: top left corner is at 0,0 and the bottom right at 95,63
ld hl,$1008
ld ix,plotsscreen
call DrawLineCompact
ld hl,SAVESSCREEN
call ifastcopy
call _getkey
ret
</wiki>

== Comments ==
There are benchmarks of some of this routines here: http://www.junemann.nl/maxcoderz/viewtopic.php?f=5&t=1940&start=15

@@ Line 386: / Line 386: @@
   call _getkey
   ret
-  </wiki>
+  </nowiki>
 == Comments ==
 There are benchmarks of some of this routines here: http://www.junemann.nl/maxcoderz/viewtopic.php?f=5&t=1940&start=15

@@ Line 114: / Line 114: @@
 === Fast Version ===
 ;Fast line routine, only sets pixels
 ;(d,e),(h,l) = (x1,y1),(x2,y2)
@@ Line 364: / Line 365: @@
 	djnz DrawY7
 	ret
 === Special case of vertical lines ===

Z80 Routines:Graphic:LineDraw - Revision history

Eeems: Fixed formatting errors

Galandros: fix

Galandros: created