440Hz.asm

SECTION "Header", ROM0[$100]

Start::
    nop
    jp _Start

SECTION "Home", ROM0[$150]
INCLUDE "common.inc"

_Start:
    ld de, $c000
    ld hl, $ff30
    ld a, $ff
    ldh [rNR51], a

    REPT 8
    ldi [hl], a
    ENDR
    xor a
    REPT 8
    ldi [hl], a
    ENDR
    
    ld a, $77
    ldh [rNR50], a
    
    ld hl, rPCM34
    ld a, $21
    ldh [rNR32], a
    
    ld a, $80
    ldh [rNR11], a
    ld a, $F0
    ldh [rNR12], a
    ld a, $D7
    ldh [rNR13], a
    ld a, $86
    ldh [rNR14], a
    ld a, $10
    ld hl, rJOYP
    ld [hl], a
    
.waitForA:
    bit 0,[hl]
    jr nz, .waitForA
    
    ld a, $00
    ldh [rNR12], a
    
    ld a, $80
    ldh [rNR30], a
    ld a, $6b
    ldh [rNR33], a
    ld a, $87 ; 2
    ldh [rNR34], a ; 3
    
    ld hl, rJOYP
.waitForB:
    bit 1,[hl]
    jr nz, .waitForB
    
    xor a
    ldh [rNR30], a
    ld hl, $ff38
    dec a
    
    REPT 8
    ldi [hl], a
    ENDR
    
    ld a, $ff
    ldh [rNR33], a
    
.loop:
    ld a, $87 ; 2
    ldh [rNR30], a ; 3
    ldh [rNR34], a ; 3
    
    nops 1191 - 12
    xor a ; 1
    ldh [rNR30], a ; 3
    
    nops 1191 - 4
    jr .loop ; 4