.word GETPIXEL
.word LINE
.word BAR
- .word CIRCLE
.word TEXTSTYLE
.word OUTTEXT
+ .word 0 ; IRQ entry is unused
; ------------------------------------------------------------------------
; Data.
Y1 = ptr2
X2 = ptr3
Y2 = ptr4
-RADIUS = tmp1
-
-ADDR = tmp1
-TEMP = tmp3
-TEMP2 = tmp4
-TEMP3 = sreg
-TEMP4 = sreg+1
-
-; Circle stuff
-XX = ptr3 ; (2) CIRCLE
-YY = ptr4 ; (2) CIRCLE
-MaxO = sreg ; (overwritten by TEMP3+TEMP4, but restored from OG/OU anyway)
-XS = regsave ; (2) CIRCLE
-YS = regsave+2 ; (2) CIRCLE
; Absolute variables used in the code
OLDCOLOR: .res 1 ; colors before entering gfx mode
-; Line routine stuff (combined with CIRCLE to save space)
+; Line routine stuff
OGora: .res 2
OUkos: .res 2
; Must set an error code: NO
;
-SETPIXELCLIP:
- lda Y1+1
- bmi @finito ; y<0
- lda X1+1
- bmi @finito ; x<0
- lda X1
- ldx X1+1
- sta ADDR
- stx ADDR+1
- ldx #ADDR
- lda xres
- ldy xres+1
- jsr icmp ; ( x < xres ) ...
- bcs @finito
- lda Y1
- ldx Y1+1
- sta ADDR
- stx ADDR+1
- ldx #ADDR
- lda yres
- ldy yres+1
- jsr icmp ; ... && ( y < yres )
- bcc SETPIXEL
-@finito:rts
-
SETPIXEL:
lda X1
ldx X1+1
sty r2H
jmp Rectangle
-; ------------------------------------------------------------------------
-; CIRCLE: Draw a circle around the center X1/Y1 (= ptr1/ptr2) with the
-; radius in tmp1 and the current drawing color.
-;
-; Must set an error code: NO
-;
-
-CIRCLE:
- lda RADIUS
- bne @L1
- jmp SETPIXELCLIP ; Plot as a point
-
-@L1: sta XX
- ; x = r;
- lda #0
- sta XX+1
- sta YY
- sta YY+1
- sta MaxO
- sta MaxO+1
- ; y =0; mo=0;
- lda X1
- ldx X1+1
- sta XS
- stx XS+1
- lda Y1
- ldx Y1+1
- sta YS
- stx YS+1 ; XS/YS to remember the center
-
- ; while (y<x) {
-@L013B: ldx #YY
- lda XX
- ldy XX+1
- jsr icmp
- bcc @L12
- rts
-@L12: ; plot points in 8 slices...
- lda XS
- clc
- adc XX
- sta X1
- lda XS+1
- adc XX+1
- sta X1+1 ; x1 = xs+x
- lda YS
- clc
- adc YY
- sta Y1
- pha
- lda YS+1
- adc YY+1
- sta Y1+1 ; (stack)=ys+y, y1=(stack)
- pha
- jsr SETPIXELCLIP ; plot(xs+x,ys+y)
- lda YS
- sec
- sbc YY
- sta Y1
- sta Y3
- lda YS+1
- sbc YY+1
- sta Y1+1 ; y3 = y1 = ys-y
- sta Y3+1
- jsr SETPIXELCLIP ; plot(xs+x,ys-y)
- pla
- sta Y1+1
- pla
- sta Y1 ; y1 = ys+y
- lda XS
- sec
- sbc XX
- sta X1
- lda XS+1
- sbc XX+1
- sta X1+1
- jsr SETPIXELCLIP ; plot (xs-x,ys+y)
- lda Y3
- sta Y1
- lda Y3+1
- sta Y1+1
- jsr SETPIXELCLIP ; plot (xs-x,ys-y)
-
- lda XS
- clc
- adc YY
- sta X1
- lda XS+1
- adc YY+1
- sta X1+1 ; x1 = xs+y
- lda YS
- clc
- adc XX
- sta Y1
- pha
- lda YS+1
- adc XX+1
- sta Y1+1 ; (stack)=ys+x, y1=(stack)
- pha
- jsr SETPIXELCLIP ; plot(xs+y,ys+x)
- lda YS
- sec
- sbc XX
- sta Y1
- sta Y3
- lda YS+1
- sbc XX+1
- sta Y1+1 ; y3 = y1 = ys-x
- sta Y3+1
- jsr SETPIXELCLIP ; plot(xs+y,ys-x)
- pla
- sta Y1+1
- pla
- sta Y1 ; y1 = ys+x(stack)
- lda XS
- sec
- sbc YY
- sta X1
- lda XS+1
- sbc YY+1
- sta X1+1
- jsr SETPIXELCLIP ; plot (xs-y,ys+x)
- lda Y3
- sta Y1
- lda Y3+1
- sta Y1+1
- jsr SETPIXELCLIP ; plot (xs-y,ys-x)
-
- ; og = mo+y+y+1
- lda MaxO
- ldx MaxO+1
- clc
- adc YY
- tay
- txa
- adc YY+1
- tax
- tya
- clc
- adc YY
- tay
- txa
- adc YY+1
- tax
- tya
- clc
- adc #1
- bcc @L0143
- inx
-@L0143: sta OGora
- stx OGora+1
- ; ou = og-x-x+1
- sec
- sbc XX
- tay
- txa
- sbc XX+1
- tax
- tya
- sec
- sbc XX
- tay
- txa
- sbc XX+1
- tax
- tya
- clc
- adc #1
- bcc @L0146
- inx
-@L0146: sta OUkos
- stx OUkos+1
- ; ++y
- inc YY
- bne @L0148
- inc YY+1
-@L0148: ; if (abs(ou)<abs(og))
- lda OUkos
- ldy OUkos+1
- jsr abs
- sta TEMP3
- sty TEMP4
- lda OGora
- ldy OGora+1
- jsr abs
- ldx #TEMP3
- jsr icmp
- bpl @L0149
- ; { --x;
- sec
- lda XX
- sbc #1
- sta XX
- bcs @L014E
- dec XX+1
-@L014E: ; mo = ou; }
- lda OUkos
- ldx OUkos+1
- jmp @L014G
- ; else { mo = og }
-@L0149: lda OGora
- ldx OGora+1
-@L014G: sta MaxO
- stx MaxO+1
- ; }
- jmp @L013B
-
; ------------------------------------------------------------------------
; TEXTSTYLE: Set the style used when calling OUTTEXT. Text scaling in X and Y
; direction is passend in X/Y, the text direction is passed in A.
bne @vertical
@end: rts
-;-------------
-; copies of some runtime routines
-
-abs:
- ; a/y := abs(a/y)
- dey
- iny
- bpl @L1
- ; negay
- clc
- eor #$ff
- adc #1
- pha
- tya
- eor #$ff
- adc #0
- tay
- pla
-@L1: rts
-
-icmp:
- ; compare a/y to zp,x
- sta TEMP ; TEMP/TEMP2 - arg2
- sty TEMP2
- lda $0,x
- pha
- lda $1,x
- tay
- pla
- tax
- tya ; x/a - arg1 (a=high)
-
- sec
- sbc TEMP2
- bne @L4
- cpx TEMP
- beq @L3
- adc #$ff
- ora #$01
-@L3: rts
-@L4: bvc @L3
- eor #$ff
- ora #$01
- rts
-
;-------------
; VDC helpers
projects / cc65 / commitdiff