61 lines
1007 B
ArmAsm
61 lines
1007 B
ArmAsm
; Spiraling Shape
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; o/~ Down, Down, Down You Go o/~
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; by Vince `deater` Weaver / DsR
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; Lovebyte 2024
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; zero page locations
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GBASL = $26
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GBASH = $27
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HGR_SCALE = $E7
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HGR_COLLISION = $EA
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HGR_ROTATION = $FE ; IMPORTANT! set this right!
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; ROM locations
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HGR2 = $F3D8
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HPOSN = $F411
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XDRAW0 = $F65D
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XDRAW1 = $F661
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HPLOT0 = $F457
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spiraling_shape:
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jsr HGR2 ; Hi-res, full screen ; 3
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; Y=0, A=0 after this call
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; A and Y are 0 here.
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; X is left behind by the boot process?
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tiny_loop:
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bit $C030
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tay ; ldy #0 ; A always 0 here
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ldx #140
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lda #96
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jsr HPOSN ; set screen position to X= (y,x) Y=(a)
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; saves X,Y,A to zero page
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; after Y= orig X/7
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; A and X are ??
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ldx #<our_shape ; load $E2DF
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ldy #>our_shape ;
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inc HGR_ROTATION
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lda #1 ; HGR_ROTATION is HERE ($FE)
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and #$7f ; cut off before it gets too awful
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sta HGR_SCALE
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jsr XDRAW0 ; XDRAW 1 AT X,Y
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; Both A and X are 0 at exit
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; Z flag set on exit
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; Y varies
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beq tiny_loop ; bra
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our_shape = $E2DF
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