mirror of
https://github.com/cc65/cc65.git
synced 2024-12-25 02:29:52 +00:00
311 lines
5.6 KiB
PHP
311 lines
5.6 KiB
PHP
;
|
|
; Oliver Schmidt <ol.sc@web.de>
|
|
;
|
|
; Generic LINE implementation based on SETPIXEL for TGI driver inclusion
|
|
; Code previously present in a2.lo.tgi, c128-vdc.tgi and c128-vdc2.tgi
|
|
;
|
|
|
|
; ------------------------------------------------------------------------
|
|
|
|
; LINE: Draw a line from X1/Y1 to X2/Y2, where X1/Y1 = ptr1/ptr2 and
|
|
; X2/Y2 = ptr3/ptr4 using the current drawing color.
|
|
; Must set an error code: NO
|
|
|
|
.proc LINE
|
|
|
|
; Used for passing parameters to the driver.
|
|
|
|
X1 := ptr1
|
|
Y1 := ptr2
|
|
X2 := ptr3
|
|
Y2 := ptr4
|
|
|
|
; These ones must be on zpage.
|
|
|
|
TEMP1 := tmp3
|
|
TEMP2 := tmp4
|
|
TEMP3 := sreg
|
|
TEMP4 := sreg+1
|
|
PB := ptr3
|
|
UB := ptr4
|
|
ERR := regsave
|
|
NX := regsave+2
|
|
|
|
; ------------------------------------------------------------------------
|
|
|
|
.bss
|
|
|
|
COUNT: .res 2
|
|
NY: .res 2
|
|
DX: .res 1
|
|
DY: .res 1
|
|
AX: .res 1
|
|
AY: .res 1
|
|
|
|
; ------------------------------------------------------------------------
|
|
|
|
.code
|
|
|
|
; nx = abs (x2 - x1)
|
|
sec
|
|
lda X2
|
|
sbc X1
|
|
sta NX
|
|
lda X2+1
|
|
sbc X1+1
|
|
tay
|
|
lda NX
|
|
jsr abs
|
|
sta NX
|
|
sty NX+1
|
|
|
|
; ny = abs (y2 - y1)
|
|
sec
|
|
lda Y2
|
|
sbc Y1
|
|
sta NY
|
|
lda Y2+1
|
|
sbc Y1+1
|
|
tay
|
|
lda NY
|
|
jsr abs
|
|
sta NY
|
|
sty NY+1
|
|
|
|
; if (x2 >= x1)
|
|
ldx #X2
|
|
lda X1
|
|
ldy X1+1
|
|
jsr icmp
|
|
bcc :+
|
|
|
|
; dx = 1
|
|
lda #$01
|
|
bne :++
|
|
|
|
; else
|
|
; dx = -1
|
|
: lda #$FF
|
|
: sta DX
|
|
|
|
; if (y2 >= y1)
|
|
ldx #Y2
|
|
lda Y1
|
|
ldy Y1+1
|
|
jsr icmp
|
|
bcc :+
|
|
|
|
; dy = 1
|
|
lda #$01
|
|
bne :++
|
|
|
|
; else
|
|
; dy = -1
|
|
: lda #$FF
|
|
: sta DY
|
|
|
|
; err = ax = ay = 0
|
|
lda #$00
|
|
sta ERR
|
|
sta ERR+1
|
|
sta AX
|
|
sta AY
|
|
|
|
; if (nx < ny) {
|
|
ldx #NX
|
|
lda NY
|
|
ldy NY+1
|
|
jsr icmp
|
|
bcs :+
|
|
|
|
; nx <-> ny
|
|
lda NX
|
|
ldx NY
|
|
sta NY
|
|
stx NX
|
|
lda NX+1
|
|
ldx NY+1
|
|
sta NY+1
|
|
stx NX+1
|
|
|
|
; ax = dx
|
|
lda DX
|
|
sta AX
|
|
|
|
; ay = dy
|
|
lda DY
|
|
sta AY
|
|
|
|
; dx = dy = 0 }
|
|
lda #$00
|
|
sta DX
|
|
sta DY
|
|
|
|
; ny = - ny
|
|
: lda NY
|
|
ldy NY+1
|
|
jsr neg
|
|
sta NY
|
|
sty NY+1
|
|
|
|
; for (count = nx; count > 0; --count) {
|
|
lda NX
|
|
ldx NX+1
|
|
sta COUNT
|
|
stx COUNT+1
|
|
for: lda COUNT ; count > 0
|
|
ora COUNT+1
|
|
bne :+
|
|
rts
|
|
|
|
; setpixel (X1, Y1)
|
|
: jsr SETPIXEL
|
|
|
|
; pb = err + ny
|
|
clc
|
|
lda ERR
|
|
adc NY
|
|
sta PB
|
|
lda ERR+1
|
|
adc NY+1
|
|
sta PB+1
|
|
tax
|
|
|
|
; ub = pb + nx
|
|
clc
|
|
lda PB
|
|
adc NX
|
|
sta UB
|
|
txa
|
|
adc NX+1
|
|
sta UB+1
|
|
|
|
; x1 = x1 + dx
|
|
ldx #$00
|
|
lda DX
|
|
bpl :+
|
|
dex
|
|
: clc
|
|
adc X1
|
|
sta X1
|
|
txa
|
|
adc X1+1
|
|
sta X1+1
|
|
|
|
; y1 = y1 + ay
|
|
ldx #$00
|
|
lda AY
|
|
bpl :+
|
|
dex
|
|
: clc
|
|
adc Y1
|
|
sta Y1
|
|
txa
|
|
adc Y1+1
|
|
sta Y1+1
|
|
|
|
; if (abs (pb) < abs (ub)) {
|
|
lda PB
|
|
ldy PB+1
|
|
jsr abs
|
|
sta TEMP3
|
|
sty TEMP4
|
|
lda UB
|
|
ldy UB+1
|
|
jsr abs
|
|
ldx #TEMP3
|
|
jsr icmp
|
|
bpl :+
|
|
|
|
; err = pb }
|
|
lda PB
|
|
ldx PB+1
|
|
jmp next
|
|
|
|
; else { x1 = x1 + ax
|
|
: ldx #$00
|
|
lda AX
|
|
bpl :+
|
|
dex
|
|
: clc
|
|
adc X1
|
|
sta X1
|
|
txa
|
|
adc X1+1
|
|
sta X1+1
|
|
|
|
; y1 = y1 + dy
|
|
ldx #$00
|
|
lda DY
|
|
bpl :+
|
|
dex
|
|
: clc
|
|
adc Y1
|
|
sta Y1
|
|
txa
|
|
adc Y1+1
|
|
sta Y1+1
|
|
|
|
; err = ub }
|
|
lda UB
|
|
ldx UB+1
|
|
next: sta ERR
|
|
stx ERR+1
|
|
|
|
; } (--count)
|
|
lda COUNT
|
|
sec
|
|
sbc #$01
|
|
sta COUNT
|
|
bcc :+
|
|
jmp for
|
|
: dec COUNT+1
|
|
jmp for
|
|
|
|
|
|
; Copies of some runtime routines
|
|
|
|
abs:
|
|
; A/Y := abs (A/Y)
|
|
cpy #$00
|
|
bpl :+
|
|
|
|
; A/Y := neg (A/Y)
|
|
neg: clc
|
|
eor #$FF
|
|
adc #$01
|
|
pha
|
|
tya
|
|
eor #$FF
|
|
adc #$00
|
|
tay
|
|
pla
|
|
: rts
|
|
|
|
icmp:
|
|
; Compare A/Y to zp,X
|
|
sta TEMP1 ; TEMP1/TEMP2 - arg2
|
|
sty TEMP2
|
|
lda $00,x
|
|
pha
|
|
lda $01,x
|
|
tay
|
|
pla
|
|
tax
|
|
tya ; X/A - arg1 (a = high)
|
|
|
|
sec
|
|
sbc TEMP2
|
|
bne :++
|
|
cpx TEMP1
|
|
beq :+
|
|
adc #$FF
|
|
ora #$01
|
|
: rts
|
|
: bvc :+
|
|
eor #$FF
|
|
ora #$01
|
|
: rts
|
|
|
|
.endproc
|