181 lines
3.0 KiB
ArmAsm
181 lines
3.0 KiB
ArmAsm
; a snowflake
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; 216 bytes
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; 209 -- remove extraneous call to HGR
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; 207 -- use bvc to check page
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; 203 -- hardcode x coords
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; 199 -- line in ZP
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; 192 -- ybase in ZP
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; 171 -- remove self-modifying code
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; 167 -- remove YBASE ininitialization
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; 161 -- only fall to 128 then recycle
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; 156 -- use lookup table
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; 145 -- drop page flipping
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; 142 -- only need one row of zeros
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GBASL = $26
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GBASH = $27
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HGRPAGE = $E6
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YLO = $FC
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XIDX = $FD
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YBASE = $FE
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LINE = $FF
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PAGE0 = $C054
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PAGE1 = $C055
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HGR = $F3E2
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HGR2 = $F3D8
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HCLR = $F3F2
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HPOSN = $F411
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snow:
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; jsr HGR
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jsr HGR2 ; 3
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move_snow:
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; 17 bytes to set page
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; bit HGRPAGE ; V set if $40 ; 3
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; bvc show_page1 ; 2
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show_page2:
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; bit PAGE1 ; 3
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; lsr HGRPAGE ; 2
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; bne doit ; 2
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show_page1:
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; bit PAGE0 ; 3
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; asl HGRPAGE ; 2
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doit:
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; jsr HCLR
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lda #24
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sta LINE
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lda YBASE ; be sure gets init at start
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and #$7f ; wrap at 128
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sta YBASE
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inc YBASE
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sta YLO
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snow_loop:
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ldy #$0 ; xhi
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ldx #130 ; xlo -- (mult of 16)+2 for code to work
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lda YLO ; ylo
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jsr HPOSN
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; y is xlo div 7
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ldx LINE
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lda offsets,X
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tax
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line_loop:
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lda flake,X
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sta (GBASL),Y
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inx
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iny
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cpy #$18
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; tya
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; and #$8
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bne line_loop
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inc YLO
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inc_smc:
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dec LINE
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bmi move_snow
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bpl snow_loop
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; 6*12 = 72 bytes
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;flake:
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; .byte $00,$00,$40,$01,$00,$00
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; .byte $00,$00,$0C,$18,$00,$00
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; .byte $00,$00,$70,$07,$00,$00
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; .byte $00,$00,$43,$61,$00,$00
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; .byte $00,$00,$4C,$19,$00,$00
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; .byte $33,$00,$70,$07,$00,$66
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; .byte $30,$06,$40,$01,$30,$06
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; .byte $3f,$06,$40,$01,$30,$7e
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; .byte $40,$07,$30,$06,$70,$01
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; .byte $7c,$07,$30,$06,$70,$1f
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; .byte $00,$18,$0F,$78,$0C,$00
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; .byte $00,$60,$40,$01,$03,$00
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flake:
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.byte $00,$00,$00,$00 ; 0
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.byte $00,$00,$40,$01,$00,$00 ; 4,8
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.byte $0C,$18,$00,$00 ;
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.byte $70,$07,$00,$00 ;
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.byte $43,$61,$00,$00 ;
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.byte $4C,$19,$00,$00 ;
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.byte $33,$00,$70,$07,$00,$66 ; 26
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.byte $30,$06,$40,$01,$30,$06 ; 32
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.byte $3f,$06,$40,$01,$30,$7e ; 38
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.byte $40,$07,$30,$06,$70,$01 ; 44
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.byte $7c,$07,$30,$06,$70,$1f ; 50
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.byte $00,$18,$0F,$78,$0C,$00 ; 56
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.byte $60,$40,$01,$03 ; 61
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offsets:
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.byte 0,4,8,12,16,20,26,32,38,44,50,56,61
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.byte 56,50,44,38,32,26,20,16,12,8,4 ; ,0
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; want to be at $3f5 to get called by &
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; jmp snow
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;floke:
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; .byte $0,$0,$1,$2,$0,$0
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; .byte $0,$0,$3,$4,$0,$0
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; .byte $0,$0,$5,$6,$0,$0
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; .byte $0,$0,$7,$8,$0,$0
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; .byte $0,$0,$9,$A,$0,$0
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; .byte $B,$0,$5,$6,$0,$C
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; .byte $D,$E,$1,$2,$d,$E
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; .byte $F,$E,$1,$2,$d,$7e
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; .byte $1,$6,$d,$e,$5,$01
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; .byte $7c,$6,$d,$e,$5,$1f
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; .byte $0,$4,$0F,$78,$3,$0
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; .byte $0,$60,$1,$2,$03,$0
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;tokens:
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; .byte $00,$40,$01,$0C
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; .byte $18,$70,$07,$43
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; .byte $61,$4C,$19,$33
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; .byte $66,$30,$06,$3F
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; 00 000000 -> 0 0 00 00 00 - 0 00 00 00 0
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; 08 000100 -> 0 1 00 00 00 - 0 00 00 00 1
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; lda flake2,X
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; asl
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; php
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; ror out
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; plp
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; ror out
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;flake2:
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; .byte $00,$08,$00
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; .byte $00,$22,$00
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; .byte $00,$1C,$00
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; .byte $00,$49,$00
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; .byte $00,$2A,$00
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; .byte $60,$1C,$05
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; .byte $14,$08,$14
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; .byte $74,$08,$17
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; .byte $0C,$14,$18
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; .byte $3C,$14,$1E
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; .byte $02,$63,$20
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; .byte $01,$08,$40
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