bank02: start disassembling sound engine copy

audio/engine/engine_1.asm

@@ -1,8 +1,293 @@
 SoundEngine1_Load:
-	dr $839f, $8478
+	or a
+	jp z, SoundEngine1_ResetSoundRegisters
+	cp $a
+	jp z, Func_002_446f
+	push bc
+	push de
+	ld [wCurrentSongID], a
+	push af
+	add a
+	add $8d
+	ld l, a
+	ld a, $40 ; 408d
+	adc 0
+	ld h, a
+	pop af
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	or h
+	jr z, Func_002_43e4
+	ld a, [hli]
+	ld [wSoundNumChannels], a
+	ld a, [hli]
+	ld [wd406], a
+	ld b, h
+	ld c, l
+	xor a
+	ld [wd402], a
+	ld de, wChannel1
+
+Func_002_43cf:
+	ld hl, wSoundNumChannels
+	srl [hl]
+	jr c, Func_002_43e7
+	jr z, Func_002_43e4
+
+Func_002_43d8:
+	ld hl, wd402
+	inc [hl]
+	ld hl, $2c
+	add hl, de
+	ld d, h
+	ld e, l
+	jr Func_002_43cf
+
+Func_002_43e4:
+	pop de
+	pop bc
+	ret
+
+Func_002_43e7:
+	ld hl, 0
+	add hl, de
+	ld a, [hli]
+	or a
+	jr z, Func_002_43f9
+	ld a, [wd406]
+	cp [hl]
+	jr nc, Func_002_43f9
+	inc bc
+	inc bc
+	jr Func_002_43d8
+
+Func_002_43f9:
+	ld h, b
+	ld l, c
+	ld a, [hli]
+	ld b, [hl]
+	inc hl
+	push hl
+	ld hl, $20
+	add hl, de
+	ld [hli], a
+	ld [hl], b
+	inc hl
+	ld [hli], a
+	ld [hl], b
+	inc hl
+	ld [hli], a
+	ld [hl], b
+	ld hl, $f
+	add hl, de
+	ld a, $21
+	ld [hli], a
+	ld a, $50
+	ld [hl], a
+	pop bc
+	ld a, [wd402]
+	push af
+	add $ab
+	ld l, a
+	ld a, $4a
+	adc 0
+	ld h, a
+	pop af
+	ld a, [wd407]
+	or [hl]
+	ld [wd407], a
+	ld h, d
+	ld l, e
+	ld a, [wCurrentSongID]
+	ld [hli], a
+	ld a, [wd406]
+	ld [hli], a
+	ld a, 8
+	ld [hli], a
+	xor a
+	ld [hli], a
+	ld [hli], a
+	ld a, 3
+	ld [hli], a
+	ld [hli], a
+	ld a, 1
+	ld [hl], a
+	jr Func_002_43d8
+
+Func_002_4443:
+	push bc
+	push de
+	ld [wCurrentSongID], a
+	push af
+	add a
+	add $8d
+	ld l, a
+	ld a, $40
+	adc 0
+	ld h, a
+	pop af
+	ld a, [hli]
+	ld h, [hl]
+	ld l, a
+	ld a, [hli]
+	and $f0
+	swap a
+	ld [wSoundNumChannels], a
+	ld a, [hli]
+	ld [wd406], a
+	ld b, h
+	ld c, l
+	ld a, 4
+	ld [wd402], a
+	ld de, wChannel5
+	jp Func_002_43cf
+
+Func_002_446f:
+	ld a, 7
+	ld [wd40b], a
+	ld [wd40c], a
+	ret
 
 SoundEngine1_Play:
-	dr $8478, $8d2d
+	dr $8478, $8d1e
+
+SoundEngine1_ResetSoundRegisters:
+	call .DoReset
+
+.DoReset:
+	push bc
+	push de
+	call SoundEngine1_TurnOffChannels
+	ld a, $77
+	ld [wSoundGlobalStereo], a
+	jr SoundEngine1_ResetEngineVariables
 
 SoundEngine1_Init:
-	dr $8d2d, $8ecc
+	push bc
+	push de
+	call SoundEngine1_ResetHWVolumes
+	ld a, $77
+	ldh [rNR50], a
+	ld [wSoundGlobalStereo], a
+
+SoundEngine1_ResetEngineVariables:
+	ld hl, wChannel1
+	ld de, $2c
+	ld a, 0
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	ld hl, wChannel1Field08
+	ld a, 1
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	add hl, de
+	ld [hl], a
+	ld a, 0
+	ld [wd407], a
+	ld [wd40b], a
+	ld [wd40c], a
+	ld a, $ff
+	ld [wCurrentWaveInst], a
+	pop de
+	pop bc
+	ret
+
+SoundEngine1_ResetHWVolumes:
+	xor a
+	ldh [rNR50], a
+	ld a, $80
+	ldh [rNR52], a
+
+SoundEngine1_TurnOffChannels:
+	ld a, 8
+	ldh [rNR10], a
+	ld [wCh1DataCurrentSweep], a
+	ldh a, [rNR52]
+	bit 0, a
+	jr z, .ch1_is_off
+	xor a
+	ldh [rNR11], a
+	ld [wCh1DataCurrentDutyLength], a
+	ld a, 8
+	ldh [rNR12], a
+	ld [wCh1DataCurrentEnvelope], a
+	xor a
+	ldh [rNR13], a
+	ld [wCh1DataCurrentFrequency], a
+	ld [wCh1DataCurrentFrequency + 1], a
+	ld a, $80
+	ldh [rNR14], a
+	xor a
+
+.ch1_is_off:
+	ldh a, [rNR52]
+	bit 1, a
+	jr z, .ch2_is_off
+	xor a
+	ldh [rNR21], a
+	ld [wCh2DataCurrentDutyLength], a
+	ldh [rNR22], a
+	ld [wCh2DataCurrentEnvelope], a
+	ldh [rNR23], a
+	ld [wCh2DataCurrentFrequency], a
+	ld [wCh2DataCurrentFrequency + 1], a
+	ld a, $80
+	ldh [rNR24], a
+
+.ch2_is_off:
+	ldh a, [rNR52]
+	bit 2, a
+	jr z, .wave_is_off
+	xor a
+	ldh [rNR32], a
+	ld [wCh3DataCurrentVolume], a
+	ld [wCh3DataCurrentFrequency + 1], a
+	ld a, $80
+	ldh [rNR34], a
+
+.wave_is_off:
+	ldh a, [rNR52]
+	bit 3, a
+	jr z, .done
+	xor a
+	ldh [rNR41], a
+	ld [wCh4DataCurrentLength], a
+	ld a, 8
+	ldh [rNR42], a
+	ld [wCh4DataCurrentEnvelope], a
+	xor a
+	ldh [rNR43], a
+	ld [wCh4DataCurrentFrequency], a
+	ld [wCh4DataCurrentFrequency + 1], a
+	ld a, $80
+	ldh [rNR44], a
+
+.done:
+	ret
+
+	dr $8df7, $8ecc