dos33fsprogs/hgr/snow3.s
2020-12-07 16:28:09 -05:00

181 lines
3.0 KiB
ArmAsm

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