mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-06-09 07:29:32 +00:00
205 lines
2.1 KiB
ArmAsm
205 lines
2.1 KiB
ArmAsm
; web -- 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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BLAH = $F5
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COUNT = $F6
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XX = $F7
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MINUSXX = $F8
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YY = $F9
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MINUSYY = $FA
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D = $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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KEYPRESS = $C000
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KEYRESET = $C010
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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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web:
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jsr HGR2
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ldx #90
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draw_next:
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stx R
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; center
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; lda #128
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; sta CX
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; lda #96
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; sta CY
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;===============================
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; draw circle
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;===============================
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; draw circle at (CX,CY) of radius R
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; signed 8-bit math so problems if R > 64?
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; XX=0 YY=R
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; D=3-2*R
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; GOTO6
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lda #0
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sta XX
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; lda R
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stx YY
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lda #3
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sec
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sbc R
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sbc R
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sta D
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jmp do_plots
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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 #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 #6
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store_D:
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adc D
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sta D
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do_plots:
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; setup constants
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lda XX
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eor #$FF
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sta MINUSXX
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inc MINUSXX
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lda YY
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eor #$FF
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sta MINUSYY
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inc MINUSYY
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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-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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; calc X co-ord
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lda #7
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sta COUNT
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pos_loop:
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lda COUNT
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and #$4
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lsr
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tay
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lda COUNT
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lsr
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bcc xnoc
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iny
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xnoc:
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; lda CX
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lda #128
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clc
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adc XX,Y
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tax
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; calc y co-ord
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lda COUNT
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lsr
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eor #$2
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tay
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; lda CY
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lda #96
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clc
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adc XX,Y
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ldy #0
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jsr HPLOT0 ; plot at (Y,X), (A)
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dec COUNT
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bpl pos_loop
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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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done:
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ldx R
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; sec
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; sbc #3
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dex
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dex
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dex
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bpl draw_next
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stop:
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jsr WAIT
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txa
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jsr WAIT
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; for once we get this for free, even though we don't need it
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jmp web
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