mirror of
https://github.com/deater/dos33fsprogs.git
synced 2025-02-12 08:32:08 +00:00
130 lines
1.6 KiB
ArmAsm
130 lines
1.6 KiB
ArmAsm
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; circle
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; zero page
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GBASL = $26
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GBASH = $27
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YY = $69
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ROW_SUM = $70
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HGR_X = $E0
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HGR_XH = $E1
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HGR_Y = $E2
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HGR_COLOR = $E4
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HGR_PAGE = $E6
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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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; soft-switches
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FULLGR = $C052
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PAGE1 = $C054
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; ROM routines
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HGR2 = $F3D8
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HPOSN = $F411 ; (Y,X),(A) (values stores in HGRX,XH,Y)
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HPLOT0 = $F457 ; plot at (Y,X), (A)
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;================================
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; Clear screen and setup graphics
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;================================
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thick_sine:
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jsr HGR2 ; set hi-res 140x192, page2, fullscreen
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; A and Y both 0 at end
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;==================
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; create sinetable
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;ldy #0 ; Y is 0
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sinetable_loop:
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tya ; 2
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and #$3f ; wrap sine at 63 entries ; 2
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cmp #$20
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php ; save pos/negative for later
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and #$1f
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cmp #$10
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bcc sin_left ; blt
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sin_right:
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; sec carry should be set here
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eor #$FF
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adc #$20 ; 32-X
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sin_left:
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tax
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lda sinetable_base,X ; 4+
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plp
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bcc sin_done
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sin_negate:
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; carry set here
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eor #$ff
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adc #0 ; FIXME: this makes things off by 1
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sin_done:
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sta sinetable,Y
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iny
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bne sinetable_loop
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;============================
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; main loop
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;============================
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draw_circle:
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ldx #0
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stx SAVEX
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circle_loop:
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lda SAVEX
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clc
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adc #$10
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tax
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lda sinetable,X
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clc
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adc #$80
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sta SAVEY
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ldx SAVEX
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lda sinetable,X
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; asl
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; $60 is midscreen
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adc #$60
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ldx SAVEY
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ldy #0
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jsr HPLOT0 ; plot at (Y,X), (A)
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inc SAVEX
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bne circle_loop
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done:
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blah:
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jmp blah
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sinetable_base:
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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
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; for bot
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; 3F5 - 7d = 378
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; jmp oval
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sinetable=$6000
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