142 lines
1.6 KiB
ArmAsm
142 lines
1.6 KiB
ArmAsm
; circles tiny -- Apple II Hires
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; D0+ used by HGR routines
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HGR_COLOR = $E4
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HGR_PAGE = $E6
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D = $F9
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XX = $FA
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YY = $FB
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R = $FC
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CX = $FD
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CY = $FE
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FRAME = $FF
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; soft-switches
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; ROM routines
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HGR2 = $F3D8 ; set hires page2 and clear $4000-$5fff
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HGR = $F3E2 ; set hires page1 and clear $2000-$3fff
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HPLOT0 = $F457 ; plot at (Y,X), (A)
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HCOLOR1 = $F6F0 ; set HGR_COLOR to value in X
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COLORTBL = $F6F6
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PLOT = $F800 ; PLOT AT Y,A (A colors output, Y preserved)
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NEXTCOL = $F85F ; COLOR=COLOR+3
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SETCOL = $F864 ; COLOR=A
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SETGR = $FB40 ; set graphics and clear LO-RES screen
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BELL2 = $FBE4
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WAIT = $FCA8 ; delay 1/2(26+27A+5A^2) us
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circles:
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jsr HGR2
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draw_next:
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inc FRAME
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ldy FRAME
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; Random Color
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; HCOLOR=1+RND(1)*7
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lda $F000,Y
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and #$7 ; mask to 0...7
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tax
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lda COLORTBL,X
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sta HGR_COLOR
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; CX
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lda $F100,Y
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and #$7f
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sta CX
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clc
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adc #$40
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; CY
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lda $F100,Y
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and #$7f
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sta CY
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clc
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adc #$40
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; R
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lda $F100,Y
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and #$3f
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sta R
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; A=40+RND(1)*200:B=40+RND(1)*100:Y=RND(1)*40
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; 3X=0:D=3-2*Y:GOTO6
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lda #0
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sta XX
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lda R
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asl
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sta YY
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lda #3
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sec
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sbc YY
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sta D
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circle_loop:
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; X=X+1
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inc XX
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; IF D>0 THEN Y=Y-1:D=D+4*(X-Y)+10
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lda D
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bmi else
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dec YY
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lda XX
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sec
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sbc YY
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asl
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asl
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clc
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adc D
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adc #10
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jmp store_D
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else:
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; ELSE D=D+4*X+6
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lda XX
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asl
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asl
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clc
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adc D
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adc #6
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store_D:
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sta D
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; HPLOT CX+X,CY+Y
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lda CX
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clc
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adc XX
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tax
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ldy #0
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lda CY
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clc
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adc YY
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jsr HPLOT0 ; plot at (Y,X), (A)
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; HPLOT CX-X,CY+Y
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; HPLOT CX+X,CY-Y
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; HPLOT CX-X,CY-Y
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; HPLOT CX+Y,CY+X
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; HPLOT CX-Y,CY+X
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; HPLOT CX+Y,CY-X
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; HPLOT CX-Y,CY-X
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; IFY>=XTHEN4
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lda YY
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cmp XX
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bcs circle_loop
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; GOTO1
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bcc draw_next
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