ys2-intro/loader/samples/minexample/minexample.s

.feature c_comments
.include "../../build/loadersymbols-c64.inc"

.ZEROPAGE
.org $10
bmp_delay: .res 1
bmp_addr: .res 2
bmp_ptr: .res 2
scr_ptr_lo: .res 1
scr_ptr: .res 2
cram_ptr: .res 2
chr_count: .res 1
vbl: .res 1
frame: .res 1
cur_frame: .res 1
frame_delay: .res 1
frame_until: .res 1
text_ptr: .res 2
timer: .res 2
timer_limit: .res 2
timer_reached: .res 2
timer_mode: .res 1
temp: .res 3

aart_lz_buffer := $fd00
.include "lz_zp.asm"

CODE_START_ADDR = $e000

.segment "CODE"

ZP=$e0
offset          = ZP+0
ZX0_src         = ZP+2
ZX0_dst         = ZP+4
bitr            = ZP+6
pntr            = ZP+7


    .org $080d

copy_start:
    sei
    lda #$35
    sta $01
    lda #>(code_end-CODE_START_ADDR)
    sta $ff
    lda #<(code_end-CODE_START_ADDR)
    sta $fe

    lda #<CODE_START_ADDR
    sta $fc
    lda #>CODE_START_ADDR
    sta $fd

    lda #<code_start
    sta $fa
    lda #>code_start
    sta $fb

@copy_loop:
    ldy #0
    lda ($fa), y
    sta ($fc), y
    inc $fc
    bne :+
    inc $fd
:
    inc $fa
    bne :+
    inc $fb
:
    lda $fe
    bne :+
    dec $ff
:
    dec $fe
    lda $fe
    ora $ff
    bne @copy_loop

    lda #$36
    sta $01
    cli
    jsr install
    sei
    lda #$35
    sta $01
    jmp CODE_START_ADDR

    .res loadraw - *
.incbin "../../build/loader-c64.prg", 2

    .res install - *
.incbin "../../build/install-c64.prg", 2

code_start:
    .org CODE_START_ADDR

    sei

    ldx #<fontname
    ldy #>fontname
    jsr loadraw

    lda #$34
    sta $01

    ldx #0
:
    lda $8000, x
    sta $d800, x
    eor #$ff
    sta $c00, x
    lda $8100, x
    sta $d900, x
    eor #$ff
    sta $d00, x
    inx
    bne :-

    lda #0
    tax
:
    .repeat 4, I
    sta $d000+(I*250), x
    .endrepeat
    inx
    cpx #250
    bne :-

    lda #$35
    sta $01

    lda #0
    sta ZX0_dst+0

    ldx #<badguy
    ldy #>badguy
    jsr loadraw

    lda #0
    sta ZX0_src
    lda #$80
    sta ZX0_src+1
    lda #0
    sta ZX0_dst
    lda #$20
    jsr zx02

    lda #127
    sta $dc0d

    and $d011
    sta $d011

    lda $dc0d
    lda $dd0d

    lda #<irq_badguy
    sta $fffe
    lda #>irq_badguy
    sta $ffff
    
    lda #$1b
    sta $d011
    lda #$d0
    sta $d012

    lda #1
    sta $d01a
    sta bmp_delay
    jsr init_bmp

    lda #0
    sta vbl

    cli

    ;lda #64
    ;sta frame_delay
    ;jsr wait_loop

    jsr intro

    lda #$0b
    sta $d011

    sei
    ldx #<introname
    ldy #>introname
    jsr loadraw

    lda #0
    sta ZX0_src
    lda #$80
    sta ZX0_src+1
    lda #0
    sta ZX0_dst
    lda #$10
    jsr zx02

    ldx #<sidname
    ldy #>sidname
    jsr loadraw

    ldx #<towername
    ldy #>towername
    jsr loadraw

    lda #<fake_kernal_irq
    sta $fffe
    lda #>fake_kernal_irq
    sta $ffff

    lda #1
    sta $d01a

    jsr run_nufli_bmp
    sei
    jsr init_2x
    lda #$0b
    sta $d011

    jsr clr_txt
    ldx #<story_writ
    ldy #>story_writ
    jsr write_txt3
    ldx #$30
    ldy #$01
    jsr init_timer
    lda #1
    sta timer_mode

    lda #0
    sta ZX0_src
    lda #$80
    sta ZX0_src+1
    lda #0
    sta ZX0_dst
    lda #$20
    jsr zx02

:
    lda timer_reached
    beq :-

    ldx #$b8
    ldy #$01
    jsr init_timer
    lda #2
    sta timer_mode
:
    lda timer_reached
    beq :-

    jsr init_bmp

    lda #0
    sta vbl

    lda #$11
    sta frame_until
    jsr wait_frame_until_2x

    ldx #$6c
:
    jsr wait_frame
    jsr wait_frame
    dex
    bpl :-

    lda #$0b
    sta $d011

    jsr clr_txt
    ldx #<scenario_writ
    ldy #>scenario_writ
    jsr write_txt2
    ldx #$80
    ldy #$01
    jsr init_timer
    lda #1
    sta timer_mode

    ldx #<towerbeamname
    ldy #>towerbeamname
    jsr loadraw
    lda #0
    sta ZX0_src
    lda #$80
    sta ZX0_src+1
    lda #0
    sta ZX0_dst
    lda #$20
    jsr zx02

:
    lda timer_reached
    beq :-

    ldx #$90
    ldy #$01
    jsr init_timer
    lda #2
    sta timer_mode
:
    lda timer_reached
    beq :-

    jsr init_bmp

    lda #0
    sta vbl

    lda #$0d
    sta frame_until
    jsr wait_frame_until_2x
    lda bmp_addr
    sta temp
    lda bmp_addr+1
    sta temp+1
    lda cur_frame
    sta temp+2

    ldx #17
:
    txa
    pha
    lda temp+2
    sta cur_frame
    lda temp
    sta bmp_addr
    lda temp+1
    sta bmp_addr+1
    lda #$0d+3
    sta frame_until
    jsr wait_frame_until_2x    
    pla
    tax
    dex
    bpl :-
    
    lda #$0b
    sta $d011

    jsr clr_txt
    ldx #<prog_writ
    ldy #>prog_writ
    jsr write_txt2
    ldx #$a8
    ldy #$01
    jsr init_timer
    lda #1
    sta timer_mode

    ldx #<fieldname
    ldy #>fieldname
    jsr loadraw
    lda #0
    sta ZX0_src
    lda #$80
    sta ZX0_src+1
    lda #0
    sta ZX0_dst
    lda #$20
    jsr zx02

:
    lda timer_reached
    beq :-

    ldx #$48
    ldy #$01
    jsr init_timer
    lda #2
    sta timer_mode

:
    lda timer_reached
    beq :-

    jsr init_bmp

    lda #0
    sta vbl

    lda #$08
    sta frame_until
    jsr wait_frame_until_2x
    lda bmp_addr
    sta temp
    lda bmp_addr+1
    sta temp+1
    lda cur_frame
    sta temp+2

    ldx #2
:
    txa
    pha
    lda temp+2
    sta cur_frame
    lda temp
    sta bmp_addr
    lda temp+1
    sta bmp_addr+1
    lda #$08+8
    sta frame_until
    jsr wait_frame_until_2x    
    pla
    tax
    dex
    bpl :-


    lda #0
    sta vbl
    lda #$27
    sta frame_until
    jsr wait_frame_until_2x    

    ldx #25
:
    jsr wait_frame
    dex
    bpl :-

    lda #$0b
    sta $d011

    jsr clr_txt
    ldx #<gart_writ
    ldy #>gart_writ
    jsr write_txt5
    ldx #$80
    ldy #$01
    jsr init_timer
    lda #1
    sta timer_mode

    ldx #<fallingstarname
    ldy #>fallingstarname
    jsr loadraw
    lda #0
    sta ZX0_src
    lda #$80
    sta ZX0_src+1
    lda #0
    sta ZX0_dst
    lda #$20
    jsr zx02

:
    lda timer_reached
    beq :-

    ldx #$48
    ldy #$01
    jsr init_timer
    lda #2
    sta timer_mode

:
    lda timer_reached
    beq :-

    jsr init_bmp

    lda #$1d
    sta frame_until
    jsr wait_frame_until_2x

    ldx #5
:
    jsr wait_frame
    dex
    bpl :-

    lda #$0b
    sta $d011

    jsr clr_txt
    ldx #<music_writ
    ldy #>music_writ
    jsr write_txt4
    ldx #$80
    ldy #$01
    jsr init_timer
    lda #1
    sta timer_mode

    ldx #<lilianame
    ldy #>lilianame
    jsr loadraw
    lda #0
    sta ZX0_src
    lda #$80
    sta ZX0_src+1
    lda #0
    sta ZX0_dst
    lda #$20
    jsr zx02

:
    lda timer_reached
    beq :-

    ldx #$10
    ldy #$01
    jsr init_timer
    lda #8*11
    sta timer
    lda #2
    sta timer_mode

:
    lda timer_reached
    beq :-

    ldx #$c4
    ldy #$01
    jsr init_timer

    jsr init_bmp

    lda #$08
    sta frame_until
    jsr wait_frame_until_2x

:
    lda timer_reached
    beq :-

    lda #$0b
    sta $d011

    jsr clr_txt
    ldx #<scene_writ
    ldy #>scene_writ
    jsr write_txt3
    ldx #$80
    ldy #$01
    jsr init_timer
    lda #1
    sta timer_mode

    ldx #<liliaheroname
    ldy #>liliaheroname
    jsr loadraw
    lda #0
    sta ZX0_src
    lda #$80
    sta ZX0_src+1
    lda #0
    sta ZX0_dst
    lda #$20
    jsr zx02

:
    lda timer_reached
    beq :-

    ldx #$20
    ldy #$01
    jsr init_timer
    lda #2
    sta timer_mode

:
    lda timer_reached
    beq :-

    jsr init_bmp
    jmp *


intro:
    lda #0
    jsr sfx_init

    lda #7
    sta frame_until
    jsr wait_frame_until

    lda #64
    sta frame_delay
    jsr wait_loop

    lda #1
    jsr sfx_init

    ldx #<darmtower_txt
    ldy #>darmtower_txt
    jsr upload_text

    lda #50*5
    sta frame_delay
    jsr wait_loop

    ldx #<empty_txt
    ldy #>empty_txt
    jsr upload_text

    lda #$0d
    sta frame_until
    jsr wait_frame_until

    ldx #<adol_win
    ldy #>adol_win
    jsr upload_text

    lda #50*5
    sta frame_delay
    jsr wait_loop

    ldx #<too_bad_txt
    ldy #>too_bad_txt
    jsr upload_text

    lda #50*5
    sta frame_delay
    jsr wait_loop

    ldx #<empty_txt
    ldy #>empty_txt
    jsr upload_text

    lda #$13
    sta frame_until
    jsr wait_frame_until

    lda #0
    jsr sfx_init

    lda #$1a
    sta frame_until
    jsr wait_frame_until

    lda #120
    sta frame_delay
    jsr wait_loop
    rts

wait_frame:
@loop:
    bit $d011
    bpl @loop
@loop2:
    bit $d011
    bmi @loop2
    rts

init_2x:
    lda #127
    sta $dc0d

    and $d011
    sta $d011

    lda $dc0d
    lda $dd0d

    lda #<irq_music
    sta $fffe
    lda #>irq_music
    sta $ffff

    lda #$0b
    sta $d011
    lda #$00
    sta $d012

    lda #0
    sta $d01a

    lda #$63; <(985248/100)
    sta $dc04
    lda #$26;>(985248/100)
    sta $dc05

    lda $dc0d
    and #$81
    sta $dc0d

    lda #$40
    sta $dc0c

    lda #$81
    sta $dc0d

@loop:
    bit $d011
    bpl @loop
@loop2:
    bit $d011
    bmi @loop2
    cli
    rts

init_timer:
    lda #0
    sta timer_reached
    sta timer_mode
    sta timer
    sta timer+1
    stx timer_limit
    sty timer_limit+1
    rts

fade_cols:
    .byte 0, 0
    .byte $0, $0, $0, $0, $b, $c, $f, $1
    .res 32-10, $1

irq_music:
	pha
    txa
    pha
    tya
    pha

    lda $dd00
    and #3
    sta @dd00_arc+1
    lda #3
    sta $dd00

    inc vbl

    ;inc $d020
    jsr $a003
    ;dec $d020

    lda timer_mode
    cmp #1
    bne :+
    lda timer+1
    bne :+
    lda timer
    lsr
    lsr
    lsr
    tax
    lda fade_cols, x
    sta $d021
:
    lda timer_mode
    cmp #2
    bne :+
    lda timer+1
    bne :+
    lda timer
    lsr
    lsr
    lsr
    eor #31
    tax
    lda fade_cols, x
    sta $d021
:

    inc timer
    bne :+
    inc timer+1
:
    lda timer
    cmp timer_limit
    bne :+
    lda timer+1
    cmp timer_limit+1
    bne :+
    lda #1
    sta timer_reached
:

@dd00_arc:
    lda #0
    sta $dd00

    pla
    tay
    pla
    tax
    pla
    jmp $dc0c
  

fake_kernal_irq:
	pha
    txa
    pha
    tya
    pha
    tsx
    lda $0104, x
    and #$10
    beq :+
    jmp ($0314)
:
    jmp ($0314) ; fuck you

wait_loop:
@loop2:
    lda vbl
    beq @loop2

    lda #0
    sta vbl

    jsr sfx_play

    dec frame_delay
    lda frame_delay
    beq :+
    jmp @loop2
:
    rts

wait_frame_until:
@loop:
    lda vbl
    beq @loop

    lda #0
    sta vbl

    lda cur_frame
    cmp #2
    bcc :+
    jsr sfx_play
:

    dec bmp_delay
    bpl :+
    jsr update_bmp
:

    lda cur_frame
    cmp frame_until
    beq :+

    jmp @loop
:
    rts


wait_loop_2x:
@loop:
    lda vbl
    cmp #2
    bcc @loop

    lda #0
    sta vbl

    dec frame_delay
    lda frame_delay
    beq :+
    jmp @loop
:
    rts

wait_frame_until_2x:
@loop:
    lda vbl
    cmp #2
    bcc @loop

    lda #0
    sta vbl

    dec bmp_delay
    bpl :+
    jsr update_bmp
:

    lda cur_frame
    cmp frame_until
    beq :+
    jmp @loop
:
    rts


init_bmp:
    lda #$0b
    sta $d011
    lda #$19
    sta $d018
    lda #$d8
    sta $d016

    lda $4710
    lsr
    lsr
    lsr
    lsr
    sta $d020

    lda $4710
    and #$0f
    sta $d021

    lda #0
    sta cur_frame
    sta bmp_delay

    lda #$11
    sta bmp_addr
    lda #$47
    sta bmp_addr+1

    ldx #0
:
    .repeat 4, I
        lda $3f40+(I*250), x
        sta $400+(I*250), x
        lda $4328+(I*250), x
        sta $d800+(I*250), x
    .endrepeat
    inx
    cpx #250
    bne :-

    lda #$3b
    sta $d011
    rts

inc_bmp_addr:
    inc bmp_addr
    bne :+
    inc bmp_addr+1
:
    rts

update_bmp:
    ldy #0
    sty scr_ptr
    sty cram_ptr
    lda (bmp_addr), y
    jsr inc_bmp_addr
    sta chr_count
    cmp #0 ; tfw flags update in inc_bmp_addr
    bne @skip_frame_end
    lda (bmp_addr), y
    jsr inc_bmp_addr
    sta bmp_delay
    inc cur_frame
    rts    
@skip_frame_end:

    lda (bmp_addr), y   
    sta bmp_ptr
    iny
    lda (bmp_addr), y   
    clc
    adc #$20
    sta bmp_ptr+1

    iny
    lda (bmp_addr), y   
    sta scr_ptr_lo
    iny
    lda (bmp_addr), y   
    clc
    adc #$04
    sta scr_ptr+1
    clc
    adc #$d8-$04
    sta cram_ptr+1

    ldy #0
    lda bmp_addr
    clc 
    adc #4
    sta bmp_addr
    bcc :+
    inc bmp_addr+1
:

    ldx #0
@loop:
    ldy #0
    lda (bmp_addr), y
    sta (bmp_ptr), y
    iny 
    lda (bmp_addr), y
    sta (bmp_ptr), y
    iny 
    lda (bmp_addr), y
    sta (bmp_ptr), y
    iny 
    lda (bmp_addr), y
    sta (bmp_ptr), y
    iny 
    lda (bmp_addr), y
    sta (bmp_ptr), y
    iny 
    lda (bmp_addr), y
    sta (bmp_ptr), y
    iny 
    lda (bmp_addr), y
    sta (bmp_ptr), y
    iny 
    lda (bmp_addr), y
    sta (bmp_ptr), y

    lda bmp_ptr
    clc
    adc #8
    sta bmp_ptr
    bcc :+
    inc bmp_ptr+1
:

    ldy #8
    lda (bmp_addr), y
    ldy scr_ptr_lo
    sta (scr_ptr), y
    
    ldy #9
    lda (bmp_addr), y
    ldy scr_ptr_lo
    sta (cram_ptr), y

    inc scr_ptr_lo
    bne :+
    inc scr_ptr+1
    inc cram_ptr+1
:

    lda bmp_addr
    clc
    adc #10
    sta bmp_addr
    bcc :+
    inc bmp_addr+1
:

    dec chr_count
    ldx chr_count
    bne @loop
    jmp update_bmp

irq_badguy:
	pha
    txa
    pha
    tya
    pha

    inc vbl
    ;inc $d020

    lda #$1b
    sta $d011
    lda #$19
    sta $d018
    lda #$c8
    sta $d016
    lda $dd00
    and #3
    sta @dd00_arc+1
    lda #0
    sta $dd00
    lda #$47
    sta $d018

:
    lda $d012
    cmp #$fb
    bcc :-

    .res 2, $ea

    lda #$3b
    sta $d011
    lda #$19
    sta $d018
    lda #$d8
    sta $d016
@dd00_arc:
    lda #0
    sta $dd00

    ;dec $d020

    asl $d019
    pla
    tay
    pla
    tax
    pla
    rti

badguy: .byte "badguy",0
fontname: .byte "font",0
sidname: .byte "sid", 0
introname: .byte "intrbmp", 0
towername: .byte "tower", 0
towerbeamname: .byte "towerbm", 0
fieldname: .byte "field", 0
fallingstarname: .byte "fallstar", 0
lilianame: .byte "lilia", 0
liliaheroname: .byte "lilhero", 0


darmtower_txt:
    .res (40-26)/2, ' '
    .byte "who silenced darm's tower?"
    .res (40-26)/2, ' '
empty_txt:
    .res 40, ' '
adol_win:
    .res (40-20)/2, ' '
    .byte "adol must have won.."
    .res (40-20)/2, ' '
too_bad_txt:
    .res (40-10)/2, ' '
    .byte "too bad..."
    .res (40-10)/2, ' '

upload_text:
    lda #$34
    sta $01

    stx text_ptr
    sty text_ptr+1

    ldy #39
:
    lda (text_ptr), y
    sec
    sbc #$20
    sta $d348+40, y
    dey
    bne :-

    lda #$35
    sta $01

    lda #1
    ldy #39
:
    sta $db48+40, y
    dey
    bne :-
    rts


run_nufli_bmp:
    lda #$01
    sta $81
    lda #$29
    sta $80
    lda #0
    sta $d01a
    jsr $a000
    cli
    jsr $3000
@loop:
    bit $d011
    bpl @loop
    jsr $a003
@loop2:
    bit $d011
    bmi @loop2
    lda #0
    sta $d020
    sta $d021
    jsr $a003
    lda $80
    bne :+
    dec $81
:
    dec $80
    lda $81
    cmp #$ff
    beq :+
    jmp @loop
:
    lda #0
    sta $d015
    rts


.res $ea31-*, $ff
    ;asl $d019
    pla
    tay
    pla
    tax
    pla
    rti

.res $ea81-*, $ff
    ;asl $d019
    pla
    tay
    pla
    tax
    pla
    rti

.include "sfx.asm"
.include "zx02.asm"
.include "thcmod_lz.asm"

story_writ:
.res 11, ' '
.byte "story written by"
.res 40-(16+11), ' '
.res 11, ' '
.res 5, ' '
.byte "takahiro ohura"
.res 40-(14+11+5), ' '
.res 11, ' '
.res 5, ' '
.byte "tomoo yamane"
.res 40-(12+11+5), ' '

scenario_writ:
.res (40-24)/2, ' '
.byte " scenario written by    "
.res (40-24)/2, ' '
.res (40-24)/2, ' '
.byte "      tomoyoshi miyazaki"
.res (40-24)/2, ' '

prog_writ:
.res (40-22)/2, ' '
.byte " programmed by        "
.res (40-22)/2, ' '
.res (40-22)/2, ' '
.byte "      masaya hashimoto"
.res (40-22)/2, ' '

gart_writ:
.res (40-24)/2, ' '
.byte "graphic arts designed by"
.res (40-24)/2, ' '
.res (40-24)/2, ' '
.byte "      takahiro ohura    "
.res (40-24)/2, ' '
.res (40-24)/2, ' '
.byte "      ayano koshiro     "
.res (40-24)/2, ' '
.res (40-24)/2, ' '
.byte "      kazuhiko tsuzuki  "
.res (40-24)/2, ' '
.res (40-24)/2, ' '
.byte "      tomoo yamane      "
.res (40-24)/2, ' '

music_writ:
.res (40-20)/2, ' '
.byte " music composed by  "
.res (40-20)/2, ' '
.res (40-20)/2, ' '
.byte "      mieko ishikawa"
.res (40-20)/2, ' '
.res (40-20)/2, ' '
.byte "      yuzo koshiro  "
.res (40-20)/2, ' '
.res (40-20)/2, ' '
.byte "      hideya nagata "
.res (40-20)/2, ' '

scene_writ:
.res (40-22)/2, ' '
.byte "scene set by          "
.res (40-22)/2, ' '
.res (40-22)/2, ' '
.byte "      seigo oketani   "
.res (40-22)/2, ' '
.res (40-22)/2, ' '
.byte "      yoshihiko kurata"
.res (40-22)/2, ' '

clr_txt:
    lda #$80
    ldx #0
:
    .repeat 4, I
        sta $400+(I*250), x
    .endrepeat
    inx
    cpx #250
    bne :-
    lda #0
    ldx #0
:
    .repeat 4, I
        sta $d800+(I*250), x
    .endrepeat
    inx
    cpx #250
    bne :-
    lda #$13
    sta $d018
    lda #$1b
    sta $d011
    rts

write_txt5:
    stx text_ptr
    sty text_ptr+1

    ldx #0
    ldy #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+8*40, x
    iny
    inx
    cpx #40
    bne :-

    ldx #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+10*40, x
    iny
    inx
    cpx #40
    bne :-

    ldx #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+12*40, x
    iny
    inx
    cpx #40
    bne :-

    ldx #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+14*40, x
    iny
    inx
    cpx #40
    bne :-

    ldx #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+16*40, x
    iny
    inx
    cpx #40
    bne :-
    rts

write_txt4:
    stx text_ptr
    sty text_ptr+1

    ldx #0
    ldy #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+9*40, x
    iny
    inx
    cpx #40
    bne :-

    ldx #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+11*40, x
    iny
    inx
    cpx #40
    bne :-

    ldx #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+13*40, x
    iny
    inx
    cpx #40
    bne :-

    ldx #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+15*40, x
    iny
    inx
    cpx #40
    bne :-

    rts

write_txt3:
    stx text_ptr
    sty text_ptr+1

    ldx #0
    ldy #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+10*40, x
    iny
    inx
    cpx #40
    bne :-

    ldx #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+12*40, x
    iny
    inx
    cpx #40
    bne :-

    ldx #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+14*40, x
    iny
    inx
    cpx #40
    bne :-
    rts

write_txt2:
    stx text_ptr
    sty text_ptr+1

    ldx #0
    ldy #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+11*40, x
    iny
    inx
    cpx #40
    bne :-

    ldx #0
:
    lda (text_ptr), y
    sec
    sbc #$20
    ora #$80
    sta $400+13*40, x
    iny
    inx
    cpx #40
    bne :-
    rts

code_end: