dos33fsprogs/demos/trogdor/flame.s

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2024-01-30 03:53:37 +00:00
; flames -- Apple II Hires
flames:
;==================================================
; clear both graphics screens, set to display page1
; lda #$20
; sta HGR_PAGE
;=============================================
; setup (draw white line at bottom of screen)
ldy #39
lda #$f
white_line_loop:
sta $5DD0,Y
dey
bpl white_line_loop
;====================
;====================
; main loop
;====================
;====================
fire_loop:
lda #$20
sta DRAW_PAGE
;====================
; move fire
;====================
move_fire:
ldx #159 ; start at bottom of screen
burn_loop:
;======================
; input in BASL/BASH
lda hposn_low,X
sta BASL
lda hposn_high,X
clc
adc DRAW_PAGE
sta BASH
;========================
; output in GBASL:GBASH
dex ; point to line above
stx XSAVE
lda hposn_low,X
sta GBASL ; put the line address into input
lda hposn_high,X
clc
adc DRAW_PAGE
sta GBASH
ldy #39 ; 39 columns across screen
burn_inner:
random_smc:
lda $900 ; our "RANDOM" numbers
; lda $E000 ; our "RANDOM" numbers
bpl dont_invert_dex ; is top bit random enough?
lda dex_smc
eor #$20
sta dex_smc
dont_invert_dex:
;burn_in_smc:
lda (BASL),Y
tax
; ldx $4000,Y
beq skip_if_zero
dex_smc: ; DEX = $CA, NOP = $EA
dex
skip_if_zero:
txa
;burn_out_smc:
; sta $4000,Y
sta (GBASL),Y
inc random_smc+1 ; update "RNG"
bne no_oflo
inc random_smc+2
lda random_smc+2
cmp #$0c
bne no_oflo
lda #$09 ; wrap to "ROM"
sta random_smc+2
no_oflo:
dey
bpl burn_inner
ldx XSAVE ; finish early as top of screen empty
cpx #120
bne burn_loop
;====================
; copy to visible
copy_to_page1:
; X should already be 150 here
; ldx #150 ; only on bottom of screen
copy_loop:
; txa
; jsr HPOSN ; puts addr of line in A into GBASL:GBASH
lda hposn_low,X ; output on page1
sta BASL
sta GBASL
lda hposn_high,X
sta BASH
clc
adc #$20
sta GBASH
stx XSAVE
; lda GBASL
; sta BASL
; sta copy_inner_smc+1
; lda GBASH
; eor #$60 ; flip to page 1
; sta BASH
; sta copy_inner_smc+2
ldy #39
copy_inner:
lda (GBASL),Y
tax
lda color_lookup,X
; sec ; or ora $80?
ror_smc:
; ror ; ROR = $6A 0110 1010
; NOP = $EA 1110 1010
copy_inner_smc:
sta (BASL),Y
; lda ror_smc
; eor $80
; sta ror_smc
dey
bpl copy_inner
ldx XSAVE
inx
cpx #160
bne copy_loop
;====================
; loop forever
check_flame_keypress:
lda KEYPRESS
bmi done_flames
jmp fire_loop ; bra
done_flames:
bit KEYRESET
rts
;=====================
color_lookup:
.byte $00 ; 1 0 00 00 00 BBBB 0
.byte $84 ; 1 0 00 01 00 BB0B 1
.byte $90 ; 1 0 01 00 00 BOBB 2
.byte $81 ; 1 0 00 00 01 BBBO 3
.byte $91 ; 1 0 01 00 01 BOBO 4
.byte $C4 ; 1 1 00 01 00 OBOB 5
.byte $D1 ; 1 1 01 00 01 OOBO 6
.byte $DA ; 1 1 01 01 01 OOOO 7
.byte $F5 ; 1 1 11 01 01 OWOO 8
.byte $DD ; 1 1 01 11 01 WOWO 9
.byte $FE ; 1 1 11 01 11 OWOW 10
.byte $DF ; 1 1 01 11 11 OOWW 11
.byte $F5 ; 1 1 11 01 01 WWOO 12
.byte $FD ; 1 1 11 11 01 WWWO 13
.byte $DF ; 1 1 01 11 11 WOWW 14
.byte $ff ; 1 1 11 11 11 WWWW 15