mirror of
https://github.com/deater/dos33fsprogs.git
synced 2025-02-06 14:30:18 +00:00
252 lines
3.1 KiB
ArmAsm
252 lines
3.1 KiB
ArmAsm
; Interference Pattern
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.include "hardware.inc"
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; zero page
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COLOR = $30
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YY = $69
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COLOR_MASK=$F8
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XPOS = $F9
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YPOS = $FA
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DRAW_PAGE=$FB
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FRAME = $FC
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SUM = $FD
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SAVEX = $FE
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SAVEY = $FF
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;================================
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; Clear screen and setup graphics
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;================================
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oval:
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bit SET_GR
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bit LORES
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bit FULLGR ; make it 40x48
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bit PAGE1
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lda #4
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sta DRAW_PAGE
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draw_oval_loop:
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inc FRAME ; increment frame
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ldx #47 ; YY from 47 downto zero
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create_yloop:
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txa
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jsr plot_setup
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ldy #39
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create_xloop:
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; lda #128
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lda FRAME
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sta SUM
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tya ; XX
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jsr calcsine_div2
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txa ; YY
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jsr calcsine
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; X (YY) is in SAVEX
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clc
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; sty SAVEY ; XX
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tya
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adc SAVEX ; XX + YY
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jsr calcsine_div2
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; clc
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; adc FRAME
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lsr ; double colors
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and #$7 ; mask
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tax
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lda colorlookup,X
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; jsr SETCOL
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sta COLOR
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txa
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pha
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tya
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pha
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jsr plot1
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pla
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tay
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pla
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tax
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; jsr PLOT1 ; PLOT (GBASL),Y
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ldx SAVEX
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dey
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bpl create_xloop
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dex
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bpl create_yloop
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lda DRAW_PAGE
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beq flip_to_2
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bit PAGE2
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lda #0
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beq done_flip
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flip_to_2:
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bit PAGE1
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lda #4
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done_flip:
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sta DRAW_PAGE
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; X and Y both $FF
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jmp draw_oval_loop ; bra
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calcsine_div2:
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lsr
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calcsine:
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stx SAVEX
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and #$3f
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tax
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rol
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rol
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rol
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bcc sinadd
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sinsub:
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lda #0
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lda SUM
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sec
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sbc sinetable-32,X
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jmp sindone
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sinadd:
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lda SUM
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clc
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adc sinetable,X
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sindone:
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sta SUM
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ldx SAVEX
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rts
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colorlookup:
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; pink
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.byte $55,$11,$33,$bb,$ff,$bb,$55
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.byte $00
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sinetable:
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; this is actually (32*sin(x))
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.byte $00,$03,$06,$09,$0C,$0F,$11,$14
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.byte $16,$18,$1A,$1C,$1D,$1E,$1F,$1F
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.byte $20,$1F,$1F,$1E,$1D,$1C,$1A,$18
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.byte $16,$14,$11,$0F,$0C,$09,$06,$03
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;.byte $00,$FD,$FA,$F7,$F4,$F1,$EF,$EC
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;.byte $EA,$E8,$E6,$E4,$E3,$E2,$E1,$E1
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;.byte $E0,$E1,$E1,$E2,$E3,$E4,$E6,$E8
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;.byte $EA,$EC,$EF,$F1,$F4,$F7,$FA,$FD
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;================================
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; plot_setup
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;================================
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; sets up GBASL/GBASH and MASK
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; Ycoord in A
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; trashes Y/A
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plot_setup:
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lsr ; shift bottom bit into carry ; 2
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tay
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bcc plot_even ; 2nt/3
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plot_odd:
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lda #$f0 ; 2
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bcs plot_c_done ; 2nt/3
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plot_even:
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lda #$0f ; 2
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plot_c_done:
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sta mask_smc1+1 ;
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sta mask_smc2+1 ;
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lda gr_offsets_l,Y ; lookup low-res memory address ; 4
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sta gbasl_smc1+1
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sta gbasl_smc2+1
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lda gr_offsets_h,Y ; 4
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clc
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adc DRAW_PAGE ; add in draw page offset ; 3
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sta gbasl_smc1+2
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sta gbasl_smc2+2
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rts
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;================================
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; plot1
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;================================
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; plots pixel of COLOR at GBASL/GBASH:Y
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; Xcoord in Y
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plot1:
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mask_smc1:
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lda #$ff ; 2
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eor #$ff ; 2
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gbasl_smc1:
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and $400,Y ; 4+
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sta COLOR_MASK ; 3
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lda COLOR ; 3
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mask_smc2:
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and #$FF ; 2
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ora COLOR_MASK ; 3
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gbasl_smc2:
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sta $400,Y ; 5
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rts ; 6
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gr_offsets_l:
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.byte <$400,<$480,<$500,<$580,<$600,<$680,<$700,<$780
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.byte <$428,<$4a8,<$528,<$5a8,<$628,<$6a8,<$728,<$7a8
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.byte <$450,<$4d0,<$550,<$5d0,<$650,<$6d0,<$750,<$7d0
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gr_offsets_h:
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.byte >$400,>$480,>$500,>$580,>$600,>$680,>$700,>$780
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.byte >$428,>$4a8,>$528,>$5a8,>$628,>$6a8,>$728,>$7a8
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.byte >$450,>$4d0,>$550,>$5d0,>$650,>$6d0,>$750,>$7d0
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