pokecrystal/audio/engine.asm

3314 lines
54 KiB
NASM

; The entire sound engine. Uses section "audio" in WRAM.
; Interfaces are in bank 0.
; Notable functions:
; FadeMusic
; PlayStereoSFX
_MapSetup_Sound_Off:: ; e8000
; restart sound operation
; clear all relevant hardware registers & wram
push hl
push de
push bc
push af
call MusicOff
ld hl, rNR50 ; channel control registers
xor a
ld [hli], a ; rNR50 ; volume/vin
ld [hli], a ; rNR51 ; sfx channels
ld a, $80 ; all channels on
ld [hli], a ; ff26 ; music channels
ld hl, rNR10 ; sound channel registers
ld e, $4 ; number of channels
.clearsound
; sound channel 1 2 3 4
xor a
ld [hli], a ; rNR10, rNR20, rNR30, rNR40 ; sweep = 0
ld [hli], a ; rNR11, rNR21, rNR31, rNR41 ; length/wavepattern = 0
ld a, $8
ld [hli], a ; rNR12, rNR22, rNR32, rNR42 ; envelope = 0
xor a
ld [hli], a ; rNR13, rNR23, rNR33, rNR43 ; frequency lo = 0
ld a, $80
ld [hli], a ; rNR14, rNR24, rNR34, rNR44 ; restart sound (freq hi = 0)
dec e
jr nz, .clearsound
ld hl, Channels ; start of channel data
ld de, ChannelsEnd - Channels ; length of area to clear (entire sound wram area)
.clearchannels ; clear Channel1-$c2bf
xor a
ld [hli], a
dec de
ld a, e
or d
jr nz, .clearchannels
ld a, $77 ; max
ld [Volume], a
call MusicOn
pop af
pop bc
pop de
pop hl
ret
; e803d
MusicFadeRestart: ; e803d
; restart but keep the music id to fade in to
ld a, [MusicFadeIDHi]
push af
ld a, [MusicFadeIDLo]
push af
call _MapSetup_Sound_Off
pop af
ld [MusicFadeIDLo], a
pop af
ld [MusicFadeIDHi], a
ret
; e8051
MusicOn: ; e8051
ld a, 1
ld [MusicPlaying], a
ret
; e8057
MusicOff: ; e8057
xor a
ld [MusicPlaying], a
ret
; e805c
_UpdateSound:: ; e805c
; called once per frame
; no use updating audio if it's not playing
ld a, [MusicPlaying]
and a
ret z
; start at ch1
xor a
ld [CurChannel], a ; just
ld [SoundOutput], a ; off
ld bc, Channel1
.loop
; is the channel active?
ld hl, Channel1Flags - Channel1
add hl, bc
bit SOUND_CHANNEL_ON, [hl]
jp z, .nextchannel
; check time left in the current note
ld hl, Channel1NoteDuration - Channel1
add hl, bc
ld a, [hl]
cp $2 ; 1 or 0?
jr c, .noteover
dec [hl]
jr .continue_sound_update
.noteover
; reset vibrato delay
ld hl, Channel1VibratoDelay - Channel1
add hl, bc
ld a, [hl]
ld hl, Channel1VibratoDelayCount - Channel1
add hl, bc
ld [hl], a
; turn vibrato off for now
ld hl, Channel1Flags2 - Channel1
add hl, bc
res SOUND_PITCH_WHEEL, [hl]
; get next note
call ParseMusic
.continue_sound_update
call ApplyPitchWheel
; duty cycle
ld hl, Channel1DutyCycle - Channel1
add hl, bc
ld a, [hli]
ld [wCurTrackDuty], a
; intensity
ld a, [hli]
ld [wCurTrackIntensity], a
; frequency
ld a, [hli]
ld [wCurTrackFrequency], a
ld a, [hl]
ld [wCurTrackFrequency + 1], a
; vibrato, noise
call HandleTrackVibrato ; handle vibrato and other things
call HandleNoise
; turn off music when playing sfx?
ld a, [SFXPriority]
and a
jr z, .next
; are we in a sfx channel right now?
ld a, [CurChannel]
cp $4
jr nc, .next
; are any sfx channels active?
; if so, mute
ld hl, Channel5Flags
bit SOUND_CHANNEL_ON, [hl]
jr nz, .restnote
ld hl, Channel6Flags
bit SOUND_CHANNEL_ON, [hl]
jr nz, .restnote
ld hl, Channel7Flags
bit SOUND_CHANNEL_ON, [hl]
jr nz, .restnote
ld hl, Channel8Flags
bit SOUND_CHANNEL_ON, [hl]
jr z, .next
.restnote
ld hl, Channel1NoteFlags - Channel1
add hl, bc
set NOTE_REST, [hl] ; Rest
.next
; are we in a sfx channel right now?
ld a, [CurChannel]
cp $4 ; sfx
jr nc, .sfx_channel
ld hl, Channel5Flags - Channel1
add hl, bc
bit SOUND_CHANNEL_ON, [hl]
jr nz, .sound_channel_on
.sfx_channel
call UpdateChannels
ld hl, Channel1Tracks - Channel1
add hl, bc
ld a, [SoundOutput]
or [hl]
ld [SoundOutput], a
.sound_channel_on
; clear note flags
ld hl, Channel1NoteFlags - Channel1
add hl, bc
xor a
ld [hl], a
.nextchannel
; next channel
ld hl, Channel2 - Channel1
add hl, bc
ld c, l
ld b, h
ld a, [CurChannel]
inc a
ld [CurChannel], a
cp $8 ; are we done?
jp nz, .loop ; do it all again
call PlayDanger
; fade music in/out
call FadeMusic
; write volume to hardware register
ld a, [Volume]
ld [rNR50], a
; write SO on/off to hardware register
ld a, [SoundOutput]
ld [rNR51], a
ret
; e8125
UpdateChannels: ; e8125
ld hl, .ChannelFnPtrs
ld a, [CurChannel]
and $7
add a
ld e, a
ld d, 0
add hl, de
ld a, [hli]
ld h, [hl]
ld l, a
jp [hl]
.ChannelFnPtrs:
dw .Channel1
dw .Channel2
dw .Channel3
dw .Channel4
; sfx ch ptrs are identical to music chs
; ..except 5
dw .Channel5
dw .Channel6
dw .Channel7
dw .Channel8
.Channel1:
ld a, [Danger]
bit 7, a
ret nz
.Channel5:
ld hl, Channel1NoteFlags - Channel1
add hl, bc
bit NOTE_UNKN_3, [hl]
jr z, .asm_e8159
;
ld a, [SoundInput]
ld [rNR10], a
.asm_e8159
bit NOTE_REST, [hl] ; rest
jr nz, .ch1rest
bit NOTE_UNKN_4, [hl]
jr nz, .asm_e81a2
bit NOTE_UNKN_1, [hl]
jr nz, .asm_e816b
bit NOTE_UNKN_6, [hl]
jr nz, .asm_e8184
jr .asm_e8175
.asm_e816b
ld a, [wCurTrackFrequency]
ld [rNR13], a
ld a, [wCurTrackFrequency + 1]
ld [rNR14], a
.asm_e8175
bit NOTE_UNKN_0, [hl]
ret z
ld a, [wCurTrackDuty]
ld d, a
ld a, [rNR11]
and $3f ; sound length
or d
ld [rNR11], a
ret
.asm_e8184
ld a, [wCurTrackDuty]
ld d, a
ld a, [rNR11]
and $3f ; sound length
or d
ld [rNR11], a
ld a, [wCurTrackFrequency]
ld [rNR13], a
ret
.ch1rest
ld a, [rNR52]
and %10001110 ; ch1 off
ld [rNR52], a
ld hl, rNR10
call ClearChannel
ret
.asm_e81a2
ld hl, wCurTrackDuty
ld a, $3f ; sound length
or [hl]
ld [rNR11], a
ld a, [wCurTrackIntensity]
ld [rNR12], a
ld a, [wCurTrackFrequency]
ld [rNR13], a
ld a, [wCurTrackFrequency + 1]
or $80
ld [rNR14], a
ret
.Channel2:
.Channel6:
ld hl, Channel1NoteFlags - Channel1
add hl, bc
bit NOTE_REST, [hl] ; rest
jr nz, .ch2rest
bit NOTE_UNKN_4, [hl]
jr nz, .asm_e8204
bit NOTE_UNKN_6, [hl]
jr nz, .asm_e81e6
bit NOTE_UNKN_0, [hl]
ret z
ld a, [wCurTrackDuty]
ld d, a
ld a, [rNR21]
and $3f ; sound length
or d
ld [rNR21], a
ret
.asm_e81db ; unused
ld a, [wCurTrackFrequency]
ld [rNR23], a
ld a, [wCurTrackFrequency + 1]
ld [rNR24], a
ret
.asm_e81e6
ld a, [wCurTrackDuty]
ld d, a
ld a, [rNR21]
and $3f ; sound length
or d
ld [rNR21], a
ld a, [wCurTrackFrequency]
ld [rNR23], a
ret
.ch2rest
ld a, [rNR52]
and %10001101 ; ch2 off
ld [rNR52], a
ld hl, rNR20
call ClearChannel
ret
.asm_e8204
ld hl, wCurTrackDuty
ld a, $3f ; sound length
or [hl]
ld [rNR21], a
ld a, [wCurTrackIntensity]
ld [rNR22], a
ld a, [wCurTrackFrequency]
ld [rNR23], a
ld a, [wCurTrackFrequency + 1]
or $80 ; initial (restart)
ld [rNR24], a
ret
.Channel3:
.Channel7:
ld hl, Channel1NoteFlags - Channel1
add hl, bc
bit NOTE_REST, [hl] ; rest
jr nz, .ch3rest
bit NOTE_UNKN_4, [hl]
jr nz, .asm_e824d
bit NOTE_UNKN_6, [hl]
jr nz, .asm_e823a
ret
.asm_e822f ; unused
ld a, [wCurTrackFrequency]
ld [rNR33], a
ld a, [wCurTrackFrequency + 1]
ld [rNR34], a
ret
.asm_e823a
ld a, [wCurTrackFrequency]
ld [rNR33], a
ret
.ch3rest
ld a, [rNR52]
and %10001011 ; ch3 off
ld [rNR52], a
ld hl, rNR30
call ClearChannel
ret
.asm_e824d
ld a, $3f
ld [rNR31], a
xor a
ld [rNR30], a
call .asm_e8268
ld a, $80
ld [rNR30], a
ld a, [wCurTrackFrequency]
ld [rNR33], a
ld a, [wCurTrackFrequency + 1]
or $80
ld [rNR34], a
ret
.asm_e8268
push hl
ld a, [wCurTrackIntensity]
and $f ; only 0-9 are valid
ld l, a
ld h, 0
; hl << 4
; each wavepattern is $f bytes long
; so seeking is done in $10s
rept 4
add hl, hl
endr
ld de, WaveSamples
add hl, de
; load wavepattern into rWave_0-rWave_f
ld a, [hli]
ld [rWave_0], a
ld a, [hli]
ld [rWave_1], a
ld a, [hli]
ld [rWave_2], a
ld a, [hli]
ld [rWave_3], a
ld a, [hli]
ld [rWave_4], a
ld a, [hli]
ld [rWave_5], a
ld a, [hli]
ld [rWave_6], a
ld a, [hli]
ld [rWave_7], a
ld a, [hli]
ld [rWave_8], a
ld a, [hli]
ld [rWave_9], a
ld a, [hli]
ld [rWave_a], a
ld a, [hli]
ld [rWave_b], a
ld a, [hli]
ld [rWave_c], a
ld a, [hli]
ld [rWave_d], a
ld a, [hli]
ld [rWave_e], a
ld a, [hli]
ld [rWave_f], a
pop hl
ld a, [wCurTrackIntensity]
and $f0
sla a
ld [rNR32], a
ret
.Channel4:
.Channel8:
ld hl, Channel1NoteFlags - Channel1
add hl, bc
bit NOTE_REST, [hl] ; rest
jr nz, .ch4rest
bit NOTE_UNKN_4, [hl]
jr nz, .asm_e82d4
ret
.asm_e82c1 ; unused
ld a, [wCurTrackFrequency]
ld [rNR43], a
ret
.ch4rest
ld a, [rNR52]
and %10000111 ; ch4 off
ld [rNR52], a
ld hl, rNR40
call ClearChannel
ret
.asm_e82d4
ld a, $3f ; sound length
ld [rNR41], a
ld a, [wCurTrackIntensity]
ld [rNR42], a
ld a, [wCurTrackFrequency]
ld [rNR43], a
ld a, $80
ld [rNR44], a
ret
; e82e7
_CheckSFX: ; e82e7
; return carry if any sfx channels are active
ld hl, Channel5Flags
bit SOUND_CHANNEL_ON, [hl]
jr nz, .sfxon
ld hl, Channel6Flags
bit SOUND_CHANNEL_ON, [hl]
jr nz, .sfxon
ld hl, Channel7Flags
bit SOUND_CHANNEL_ON, [hl]
jr nz, .sfxon
ld hl, Channel8Flags
bit SOUND_CHANNEL_ON, [hl]
jr nz, .sfxon
and a
ret
.sfxon
scf
ret
; e8307
PlayDanger: ; e8307
ld a, [Danger]
bit 7, a
ret z
and $7f
ld d, a
call _CheckSFX
jr c, .asm_e8335
and a
jr z, .asm_e8323
cp 16 ; halfway
jr z, .asm_e831e
jr .asm_e8335
.asm_e831e
ld hl, Tablee8354
jr .updatehw
.asm_e8323
ld hl, Tablee8350
.updatehw
xor a
ld [rNR10], a ; sweep off
ld a, [hli]
ld [rNR11], a ; sound length / duty cycle
ld a, [hli]
ld [rNR12], a ; ch1 volume envelope
ld a, [hli]
ld [rNR13], a ; ch1 frequency lo
ld a, [hli]
ld [rNR14], a ; ch1 frequency hi
.asm_e8335
ld a, d
inc a
cp 30
jr c, .asm_e833c
xor a
.asm_e833c
or $80
ld [Danger], a
; is hw ch1 on?
ld a, [SoundOutput]
and $11
ret nz
; if not, turn it on
ld a, [SoundOutput]
or $11
ld [SoundOutput], a
ret
; e8350
Tablee8350: ; e8350
db $80 ; duty 50%
db $e2 ; volume 14, envelope decrease sweep 2
db $50 ; frequency: $750
db $87 ; restart sound
; e8354
Tablee8354: ; e8354
db $80 ; duty 50%
db $e2 ; volume 14, envelope decrease sweep 2
db $ee ; frequency: $6ee
db $86 ; restart sound
; e8358
FadeMusic: ; e8358
; fade music if applicable
; usage:
; write to MusicFade
; song fades out at the given rate
; load song id in MusicFadeID
; fade new song in
; notes:
; max # frames per volume level is $3f
; fading?
ld a, [MusicFade]
and a
ret z
; has the count ended?
ld a, [MusicFadeCount]
and a
jr z, .update
; count down
dec a
ld [MusicFadeCount], a
ret
.update
ld a, [MusicFade]
ld d, a
; get new count
and $3f
ld [MusicFadeCount], a
; get SO1 volume
ld a, [Volume]
and $7
; which way are we fading?
bit 7, d
jr nz, .fadein
; fading out
and a
jr z, .novolume
dec a
jr .updatevolume
.novolume
; make sure volume is off
xor a
ld [Volume], a
; did we just get on a bike?
ld a, [PlayerState]
cp $1 ; bicycle
jr z, .bicycle
push bc
; restart sound
call MusicFadeRestart
; get new song id
ld a, [MusicFadeIDLo]
and a
jr z, .quit ; this assumes there are fewer than 256 songs!
ld e, a
ld a, [MusicFadeIDHi]
ld d, a
; load new song
call _PlayMusic
.quit
; cleanup
pop bc
; stop fading
xor a
ld [MusicFade], a
ret
.bicycle
push bc
; restart sound
call MusicFadeRestart
; this turns the volume up
; turn it back down
xor a
ld [Volume], a
; get new song id
ld a, [MusicFadeIDLo]
ld e, a
ld a, [MusicFadeIDHi]
ld d, a
; load new song
call _PlayMusic
pop bc
; fade in
ld hl, MusicFade
set 7, [hl]
ret
.fadein
; are we done?
cp $7
jr nc, .maxvolume
; inc volume
inc a
jr .updatevolume
.maxvolume
; we're done
xor a
ld [MusicFade], a
ret
.updatevolume
; hi = lo
ld d, a
swap a
or d
ld [Volume], a
ret
; e83d1
LoadNote: ; e83d1
; wait for pitch wheel to finish
ld hl, Channel1Flags2 - Channel1
add hl, bc
bit SOUND_PITCH_WHEEL, [hl]
ret z
; get note duration
ld hl, Channel1NoteDuration - Channel1
add hl, bc
ld a, [hl]
ld hl, wCurNoteDuration
sub [hl]
jr nc, .ok
ld a, 1
.ok
ld [hl], a
; get frequency
ld hl, Channel1Frequency - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
; get direction of pitch wheel
ld hl, Channel1PitchWheelTarget - Channel1
add hl, bc
ld a, e
sub [hl]
ld e, a
ld a, d
sbc a, 0
ld d, a
ld hl, Channel1PitchWheelTarget + 1 - Channel1
add hl, bc
sub [hl]
jr nc, .greater_than
ld hl, Channel1Flags3 - Channel1
add hl, bc
set SOUND_PITCH_WHEEL_DIR, [hl]
; get frequency
ld hl, Channel1Frequency - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
; ????
ld hl, Channel1PitchWheelTarget - Channel1
add hl, bc
ld a, [hl]
sub e
ld e, a
ld a, d
sbc a, 0
ld d, a
; ????
ld hl, Channel1PitchWheelTarget + 1 - Channel1
add hl, bc
ld a, [hl]
sub d
ld d, a
jr .resume
.greater_than
ld hl, Channel1Flags3 - Channel1
add hl, bc
res SOUND_PITCH_WHEEL_DIR, [hl]
; get frequency
ld hl, Channel1Frequency - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
; get distance from pitch wheel target
ld hl, Channel1PitchWheelTarget - Channel1
add hl, bc
ld a, e
sub [hl]
ld e, a
ld a, d
sbc a, 0
ld d, a
ld hl, Channel1PitchWheelTarget + 1 - Channel1
add hl, bc
sub [hl]
ld d, a
.resume
; de = x * [wCurNoteDuration] + y
; x + 1 -> d
; y -> a
push bc
ld hl, wCurNoteDuration
ld b, 0 ; quotient
.loop
inc b
ld a, e
sub [hl]
ld e, a
jr nc, .loop
ld a, d
and a
jr z, .quit
dec d
jr .loop
.quit
ld a, e ; remainder
add [hl]
ld d, b ; quotient
pop bc
ld hl, Channel1PitchWheelAmount - Channel1
add hl, bc
ld [hl], d ; quotient
ld hl, Channel1PitchWheelAmountFraction - Channel1
add hl, bc
ld [hl], a ; remainder
ld hl, Channel1Field0x25 - Channel1
add hl, bc
xor a
ld [hl], a
ret
; e8466
HandleTrackVibrato: ; e8466
; handle duty, cry pitch, and vibrato
ld hl, Channel1Flags2 - Channel1
add hl, bc
bit SOUND_DUTY, [hl] ; duty
jr z, .next
ld hl, Channel1SFXDutyLoop - Channel1
add hl, bc
ld a, [hl]
rlca
rlca
ld [hl], a
and $c0
ld [wCurTrackDuty], a
ld hl, Channel1NoteFlags - Channel1
add hl, bc
set NOTE_UNKN_0, [hl]
.next
ld hl, Channel1Flags2 - Channel1
add hl, bc
bit SOUND_CRY_PITCH, [hl]
jr z, .vibrato
ld hl, Channel1CryPitch - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
ld hl, wCurTrackFrequency
ld a, [hli]
ld h, [hl]
ld l, a
add hl, de
ld e, l
ld d, h
ld hl, wCurTrackFrequency
ld [hl], e
inc hl
ld [hl], d
.vibrato
; is vibrato on?
ld hl, Channel1Flags2 - Channel1
add hl, bc
bit SOUND_VIBRATO, [hl] ; vibrato
jr z, .quit
; is vibrato active for this note yet?
; is the delay over?
ld hl, Channel1VibratoDelayCount - Channel1
add hl, bc
ld a, [hl]
and a
jr nz, .subexit
; is the extent nonzero?
ld hl, Channel1VibratoExtent - Channel1
add hl, bc
ld a, [hl]
and a
jr z, .quit
; save it for later
ld d, a
; is it time to toggle vibrato up/down?
ld hl, Channel1VibratoRate - Channel1
add hl, bc
ld a, [hl]
and $f ; count
jr z, .toggle
.subexit
dec [hl]
jr .quit
.toggle
; refresh count
ld a, [hl]
swap [hl]
or [hl]
ld [hl], a
; ????
ld a, [wCurTrackFrequency]
ld e, a
; toggle vibrato up/down
ld hl, Channel1Flags3 - Channel1
add hl, bc
bit SOUND_VIBRATO_DIR, [hl] ; vibrato up/down
jr z, .down
; up
; vibrato down
res SOUND_VIBRATO_DIR, [hl]
; get the delay
ld a, d
and $f ; lo
;
ld d, a
ld a, e
sub d
jr nc, .asm_e84ef
ld a, 0
jr .asm_e84ef
.down
; vibrato up
set SOUND_VIBRATO_DIR, [hl]
; get the delay
ld a, d
and $f0 ; hi
swap a ; move it to lo
;
add e
jr nc, .asm_e84ef
ld a, $ff
.asm_e84ef
ld [wCurTrackFrequency], a
;
ld hl, Channel1NoteFlags - Channel1
add hl, bc
set NOTE_UNKN_6, [hl]
.quit
ret
; e84f9
ApplyPitchWheel: ; e84f9
; quit if pitch wheel inactive
ld hl, Channel1Flags2 - Channel1
add hl, bc
bit SOUND_PITCH_WHEEL, [hl]
ret z
; de = Frequency
ld hl, Channel1Frequency - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
; check whether pitch wheel is going up or down
ld hl, Channel1Flags3 - Channel1
add hl, bc
bit SOUND_PITCH_WHEEL_DIR, [hl]
jr z, .decreasing
; frequency += [Channel*PitchWheelAmount]
ld hl, Channel1PitchWheelAmount - Channel1
add hl, bc
ld l, [hl]
ld h, 0
add hl, de
ld d, h
ld e, l
; [Channel*Field0x25] += [Channel*PitchWheelAmountFraction]
; if rollover: Frequency += 1
ld hl, Channel1PitchWheelAmountFraction - Channel1
add hl, bc
ld a, [hl]
ld hl, Channel1Field0x25 - Channel1
add hl, bc
add [hl]
ld [hl], a
ld a, 0
adc e
ld e, a
ld a, 0
adc d
ld d, a
; Compare the dw at [Channel*PitchWheelTarget] to de.
; If frequency is greater, we're finished.
; Otherwise, load the frequency and set two flags.
ld hl, Channel1PitchWheelTarget + 1 - Channel1
add hl, bc
ld a, [hl]
cp d
jp c, .finished_pitch_wheel
jr nz, .continue_pitch_wheel
ld hl, Channel1PitchWheelTarget - Channel1
add hl, bc
ld a, [hl]
cp e
jp c, .finished_pitch_wheel
jr .continue_pitch_wheel
.decreasing
; frequency -= [Channel*PitchWheelAmount]
ld a, e
ld hl, Channel1PitchWheelAmount - Channel1
add hl, bc
ld e, [hl]
sub e
ld e, a
ld a, d
sbc a, 0
ld d, a
; [Channel*Field0x25] *= 2
; if rollover: Frequency -= 1
ld hl, Channel1PitchWheelAmountFraction - Channel1
add hl, bc
ld a, [hl]
add a
ld [hl], a
ld a, e
sbc a, 0
ld e, a
ld a, d
sbc a, 0
ld d, a
; Compare the dw at [Channel*PitchWheelTarget] to de.
; If frequency is lower, we're finished.
; Otherwise, load the frequency and set two flags.
ld hl, Channel1PitchWheelTarget + 1 - Channel1
add hl, bc
ld a, d
cp [hl]
jr c, .finished_pitch_wheel
jr nz, .continue_pitch_wheel
ld hl, Channel1PitchWheelTarget - Channel1
add hl, bc
ld a, e
cp [hl]
jr nc, .continue_pitch_wheel
.finished_pitch_wheel
ld hl, Channel1Flags2 - Channel1
add hl, bc
res SOUND_PITCH_WHEEL, [hl]
ld hl, Channel1Flags3 - Channel1
add hl, bc
res SOUND_PITCH_WHEEL_DIR, [hl]
ret
.continue_pitch_wheel
ld hl, Channel1Frequency - Channel1
add hl, bc
ld [hl], e
inc hl
ld [hl], d
ld hl, Channel1NoteFlags - Channel1
add hl, bc
set NOTE_UNKN_1, [hl]
set NOTE_UNKN_0, [hl]
ret
; e858c
HandleNoise: ; e858c
; is noise sampling on?
ld hl, Channel1Flags - Channel1
add hl, bc
bit SOUND_NOISE, [hl] ; noise sampling
ret z
; are we in a sfx channel?
ld a, [CurChannel]
bit 2, a ; sfx
jr nz, .next
; is ch8 on? (noise)
ld hl, Channel8Flags
bit SOUND_CHANNEL_ON, [hl] ; on?
jr z, .next
; is ch8 playing noise?
bit SOUND_NOISE, [hl]
ret nz ; quit if so
;
.next
ld a, [wNoiseSampleDelay]
and a
jr z, ReadNoiseSample
dec a
ld [wNoiseSampleDelay], a
ret
; e85af
ReadNoiseSample: ; e85af
; sample struct:
; [wx] [yy] [zz]
; w: ? either 2 or 3
; x: duration
; zz: intensity
; yy: frequency
; de = [NoiseSampleAddress]
ld hl, NoiseSampleAddress
ld e, [hl]
inc hl
ld d, [hl]
; is it empty?
ld a, e
or d
jr z, .quit
ld a, [de]
inc de
cp $ff
jr z, .quit
and $f
inc a
ld [wNoiseSampleDelay], a
ld a, [de]
inc de
ld [wCurTrackIntensity], a
ld a, [de]
inc de
ld [wCurTrackFrequency], a
xor a
ld [wCurTrackFrequency + 1], a
ld hl, NoiseSampleAddress
ld [hl], e
inc hl
ld [hl], d
ld hl, Channel1NoteFlags - Channel1
add hl, bc
set NOTE_UNKN_4, [hl]
ret
.quit
ret
; e85e1
ParseMusic: ; e85e1
; parses until a note is read or the song is ended
call GetMusicByte ; store next byte in a
cp $ff ; is the song over?
jr z, .endchannel
cp $d0 ; is it a note?
jr c, .readnote
; then it's a command
.readcommand
call ParseMusicCommand
jr ParseMusic ; start over
.readnote
; CurMusicByte contains current note
; special notes
ld hl, Channel1Flags - Channel1
add hl, bc
bit SOUND_SFX, [hl]
jp nz, ParseSFXOrRest
bit SOUND_REST, [hl] ; rest
jp nz, ParseSFXOrRest
bit SOUND_NOISE, [hl] ; noise sample
jp nz, GetNoiseSample
; normal note
; set note duration (bottom nybble)
ld a, [CurMusicByte]
and $f
call SetNoteDuration
; get note pitch (top nybble)
ld a, [CurMusicByte]
swap a
and $f
jr z, .rest ; pitch 0-> rest
; update pitch
ld hl, Channel1Pitch - Channel1
add hl, bc
ld [hl], a
; store pitch in e
ld e, a
; store octave in d
ld hl, Channel1Octave - Channel1
add hl, bc
ld d, [hl]
; update frequency
call GetFrequency
ld hl, Channel1Frequency - Channel1
add hl, bc
ld [hl], e
inc hl
ld [hl], d
; ????
ld hl, Channel1NoteFlags - Channel1
add hl, bc
set NOTE_UNKN_4, [hl]
jp LoadNote
.rest
; note = rest
ld hl, Channel1NoteFlags - Channel1
add hl, bc
set NOTE_REST, [hl] ; Rest
ret
;
.endchannel
; $ff is reached in music data
ld hl, Channel1Flags - Channel1
add hl, bc
bit SOUND_SUBROUTINE, [hl] ; in a subroutine?
jr nz, .readcommand ; execute
ld a, [CurChannel]
cp $4 ; channels 0-3?
jr nc, .chan_5to8
; ????
ld hl, Channel5Flags - Channel1
add hl, bc
bit SOUND_CHANNEL_ON, [hl]
jr nz, .ok
.chan_5to8
ld hl, Channel1Flags - Channel1
add hl, bc
bit SOUND_REST, [hl]
call nz, RestoreVolume
; end music
ld a, [CurChannel]
cp $4 ; channel 5?
jr nz, .ok
; ????
xor a
ld [rNR10], a ; sweep = 0
.ok
; stop playing
; turn channel off
ld hl, Channel1Flags - Channel1
add hl, bc
res SOUND_CHANNEL_ON, [hl]
; note = rest
ld hl, Channel1NoteFlags - Channel1
add hl, bc
set NOTE_REST, [hl]
; clear music id & bank
ld hl, Channel1MusicID - Channel1
add hl, bc
xor a
ld [hli], a ; id hi
ld [hli], a ; id lo
ld [hli], a ; bank
ret
; e8679
RestoreVolume: ; e8679
; ch5 only
ld a, [CurChannel]
cp $4
ret nz
xor a
ld hl, Channel6CryPitch
ld [hli], a
ld [hl], a
ld hl, Channel8CryPitch
ld [hli], a
ld [hl], a
ld a, [LastVolume]
ld [Volume], a
xor a
ld [LastVolume], a
ld [SFXPriority], a
ret
; e8698
ParseSFXOrRest: ; e8698
; turn noise sampling on
ld hl, Channel1NoteFlags - Channel1
add hl, bc
set NOTE_UNKN_4, [hl] ; noise sample
; update note duration
ld a, [CurMusicByte]
call SetNoteDuration ; top nybble doesnt matter?
; update intensity from next param
call GetMusicByte
ld hl, Channel1Intensity - Channel1
add hl, bc
ld [hl], a
; update lo frequency from next param
call GetMusicByte
ld hl, Channel1FrequencyLo - Channel1
add hl, bc
ld [hl], a
; are we on the last channel? (noise sampling)
ld a, [CurChannel]
and $3
cp $3
ret z
; update hi frequency from next param
call GetMusicByte
ld hl, Channel1FrequencyHi - Channel1
add hl, bc
ld [hl], a
ret
; e86c5
GetNoiseSample: ; e86c5
; load ptr to sample header in NoiseSampleAddress
; are we on the last channel?
ld a, [CurChannel]
and $3
cp $3
; ret if not
ret nz
; update note duration
ld a, [CurMusicByte]
and $f
call SetNoteDuration
; check current channel
ld a, [CurChannel]
bit 2, a ; are we in a sfx channel?
jr nz, .sfx
ld hl, Channel8Flags
bit SOUND_CHANNEL_ON, [hl] ; is ch8 on? (noise)
ret nz
ld a, [MusicNoiseSampleSet]
jr .next
.sfx
ld a, [SFXNoiseSampleSet]
.next
; load noise sample set id into de
ld e, a
ld d, 0
; load ptr to noise sample set in hl
ld hl, Drumkits
add hl, de
add hl, de
ld a, [hli]
ld h, [hl]
ld l, a
; get pitch
ld a, [CurMusicByte]
swap a
; non-rest note?
and $f
ret z
; use 'pitch' to seek noise sample set
ld e, a
ld d, 0
add hl, de
add hl, de
; load sample pointer into NoiseSampleAddress
ld a, [hli]
ld [NoiseSampleAddressLo], a
ld a, [hl]
ld [NoiseSampleAddressHi], a
; clear ????
xor a
ld [wNoiseSampleDelay], a
ret
; e870f
ParseMusicCommand: ; e870f
; reload command
ld a, [CurMusicByte]
; get command #
sub a, $d0 ; first command
ld e, a
ld d, 0
; seek command pointer
ld hl, MusicCommands
add hl, de
add hl, de
; jump to the new pointer
ld a, [hli]
ld h, [hl]
ld l, a
jp [hl]
; e8720
MusicCommands: ; e8720
; pointer to each command in order
; octaves
dw Music_Octave8 ; octave 8
dw Music_Octave7 ; octave 7
dw Music_Octave6 ; octave 6
dw Music_Octave5 ; octave 5
dw Music_Octave4 ; octave 4
dw Music_Octave3 ; octave 3
dw Music_Octave2 ; octave 2
dw Music_Octave1 ; octave 1
dw Music_NoteType ; note length + intensity
dw Music_ForceOctave ; set starting octave
dw Music_Tempo ; tempo
dw Music_DutyCycle ; duty cycle
dw Music_Intensity ; intensity
dw Music_SoundStatus ; update sound status
dw Music_SoundDuty ; sfx duty
dw Music_ToggleSFX ; sound on/off
dw Music_SlidePitchTo ; pitch wheel
dw Music_Vibrato ; vibrato
dw MusicE2 ; unused
dw Music_ToggleNoise ; music noise sampling
dw Music_Panning ; force panning
dw Music_Volume ; volume
dw Music_Tone ; tone
dw MusicE7 ; unused
dw MusicE8 ; unused
dw Music_TempoRelative ; global tempo
dw Music_RestartChannel ; restart current channel from header
dw Music_NewSong ; new song
dw Music_SFXPriorityOn ; sfx priority on
dw Music_SFXPriorityOff ; sfx priority off
dw MusicEE ; unused
dw Music_StereoPanning ; stereo panning
dw Music_SFXToggleNoise ; sfx noise sampling
dw MusicF1 ; nothing
dw MusicF2 ; nothing
dw MusicF3 ; nothing
dw MusicF4 ; nothing
dw MusicF5 ; nothing
dw MusicF6 ; nothing
dw MusicF7 ; nothing
dw MusicF8 ; nothing
dw MusicF9 ; unused
dw Music_SetCondition ; setcondition
dw Music_JumpIf ; jumpif
dw Music_JumpChannel ; jump
dw Music_LoopChannel ; loop
dw Music_CallChannel ; call
dw Music_EndChannel ; return
; e8780
MusicF1: ; e8780
MusicF2: ; e8780
MusicF3: ; e8780
MusicF4: ; e8780
MusicF5: ; e8780
MusicF6: ; e8780
MusicF7: ; e8780
MusicF8: ; e8780
ret
; e8781
Music_EndChannel: ; e8781
; called when $ff is encountered w/ subroutine flag set
; end music stream
; return to caller of the subroutine
; reset subroutine flag
ld hl, Channel1Flags - Channel1
add hl, bc
res SOUND_SUBROUTINE, [hl]
; copy LastMusicAddress to MusicAddress
ld hl, Channel1LastMusicAddress - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld [hl], e
inc hl
ld [hl], d
ret
; e8796
Music_CallChannel: ; e8796
; call music stream (subroutine)
; parameters: ll hh ; pointer to subroutine
; get pointer from next 2 bytes
call GetMusicByte
ld e, a
call GetMusicByte
ld d, a
push de
; copy MusicAddress to LastMusicAddress
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
ld hl, Channel1LastMusicAddress - Channel1
add hl, bc
ld [hl], e
inc hl
ld [hl], d
; load pointer into MusicAddress
pop de
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld [hl], e
inc hl
ld [hl], d
; set subroutine flag
ld hl, Channel1Flags - Channel1
add hl, bc
set SOUND_SUBROUTINE, [hl]
ret
; e87bc
Music_JumpChannel: ; e87bc
; jump
; parameters: ll hh ; pointer
; get pointer from next 2 bytes
call GetMusicByte
ld e, a
call GetMusicByte
ld d, a
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld [hl], e
inc hl
ld [hl], d
ret
; e87cc
Music_LoopChannel: ; e87cc
; loops xx - 1 times
; 00: infinite
; params: 3
; xx ll hh
; xx : loop count
; ll hh : pointer
; get loop count
call GetMusicByte
ld hl, Channel1Flags - Channel1
add hl, bc
bit SOUND_LOOPING, [hl] ; has the loop been initiated?
jr nz, .checkloop
and a ; loop counter 0 = infinite
jr z, .loop
; initiate loop
dec a
set SOUND_LOOPING, [hl] ; set loop flag
ld hl, Channel1LoopCount - Channel1
add hl, bc
ld [hl], a ; store loop counter
.checkloop
ld hl, Channel1LoopCount - Channel1
add hl, bc
ld a, [hl]
and a ; are we done?
jr z, .endloop
dec [hl]
.loop
; get pointer
call GetMusicByte
ld e, a
call GetMusicByte
ld d, a
; load new pointer into MusicAddress
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld [hl], e
inc hl
ld [hl], d
ret
.endloop
; reset loop flag
ld hl, Channel1Flags - Channel1
add hl, bc
res SOUND_LOOPING, [hl]
; skip to next command
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
inc de ; skip
inc de ; pointer
ld [hl], d
dec hl
ld [hl], e
ret
; e880e
Music_SetCondition: ; e880e
; set condition for a jump
; used with FB
; params: 1
; xx ; condition
; set condition
call GetMusicByte
ld hl, Channel1Condition - Channel1
add hl, bc
ld [hl], a
ret
; e8817
Music_JumpIf: ; e8817
; conditional jump
; used with FA
; params: 3
; xx: condition
; ll hh: pointer
; check condition
; a = condition
call GetMusicByte
; if existing condition matches, jump to new address
ld hl, Channel1Condition - Channel1
add hl, bc
cp [hl]
jr z, .jump
; skip to next command
; get address
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
; skip pointer
inc de
inc de
; update address
ld [hl], d
dec hl
ld [hl], e
ret
.jump
; jump to the new address
; get pointer
call GetMusicByte
ld e, a
call GetMusicByte
ld d, a
; update pointer in MusicAddress
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld [hl], e
inc hl
ld [hl], d
ret
; e883e
MusicEE; e883e
; conditional jump
; checks a byte in ram corresponding to the current channel
; doesn't seem to be set by any commands
; params: 2
; ll hh ; pointer
; if ????, jump
; get channel
ld a, [CurChannel]
and $3 ; ch0-3
ld e, a
ld d, 0
; hl = Channel1JumpCondition + channel id
ld hl, Channel1JumpCondition
add hl, de
; if set, jump
ld a, [hl]
and a
jr nz, .jump
; skip to next command
; get address
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
; skip pointer
inc de
inc de
; update address
ld [hl], d
dec hl
ld [hl], e
ret
.jump
; reset jump flag
ld [hl], 0
; de = pointer
call GetMusicByte
ld e, a
call GetMusicByte
ld d, a
; update address
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld [hl], e
inc hl
ld [hl], d
ret
; e886d
MusicF9: ; e886d
; sets some flag
; seems to be unused
; params: 0
ld a, 1
ld [wc2b5], a
ret
; e8873
MusicE2: ; e8873
; seems to have been dummied out
; params: 1
call GetMusicByte
ld hl, Channel1Field0x2c - Channel1
add hl, bc
ld [hl], a
ld hl, Channel1Flags2 - Channel1
add hl, bc
set SOUND_UNKN_0B, [hl]
ret
; e8882
Music_Vibrato: ; e8882
; vibrato
; params: 2
; 1: [xx]
; delay in frames
; 2: [yz]
; y: extent
; z: rate (# frames per cycle)
; set vibrato flag?
ld hl, Channel1Flags2 - Channel1
add hl, bc
set SOUND_VIBRATO, [hl]
; start at lower frequency (extent is positive)
ld hl, Channel1Flags3 - Channel1
add hl, bc
res SOUND_VIBRATO_DIR, [hl]
; get delay
call GetMusicByte
; update delay
ld hl, Channel1VibratoDelay - Channel1
add hl, bc
ld [hl], a
; update delay count
ld hl, Channel1VibratoDelayCount - Channel1
add hl, bc
ld [hl], a
; update extent
; this is split into halves only to get added back together at the last second
; get extent/rate
call GetMusicByte
ld hl, Channel1VibratoExtent - Channel1
add hl, bc
ld d, a
; get top nybble
and $f0
swap a
srl a ; halve
ld e, a
adc a, 0; round up
swap a
or e
ld [hl], a
; update rate
ld hl, Channel1VibratoRate - Channel1
add hl, bc
; get bottom nybble
ld a, d
and $f
ld d, a
swap a
or d
ld [hl], a
ret
; e88bd
Music_SlidePitchTo: ; e88bd
; ????
; params: 2
call GetMusicByte
ld [wCurNoteDuration], a
call GetMusicByte
ld d, a
and $f
ld e, a
ld a, d
swap a
and $f
ld d, a
call GetFrequency
ld hl, Channel1PitchWheelTarget - Channel1
add hl, bc
ld [hl], e
ld hl, Channel1PitchWheelTarget + 1 - Channel1
add hl, bc
ld [hl], d
ld hl, Channel1Flags2 - Channel1
add hl, bc
set SOUND_PITCH_WHEEL, [hl]
ret
; e88e4
Music_Tone: ; e88e4
; tone
; params: 2
ld hl, Channel1Flags2 - Channel1
add hl, bc
set SOUND_CRY_PITCH, [hl]
ld hl, Channel1CryPitch + 1 - Channel1
add hl, bc
call GetMusicByte
ld [hld], a
call GetMusicByte
ld [hl], a
ret
; e88f7
MusicE7: ; e88f7
; unused
; params: 1
ld hl, Channel1Flags2 - Channel1
add hl, bc
set SOUND_UNKN_0E, [hl]
call GetMusicByte
ld hl, Channel1Field0x29 - Channel1
add hl, bc
ld [hl], a
ret
; e8906
Music_SoundDuty: ; e8906
; ???? + duty cycle
; params: 1
;
ld hl, Channel1Flags2 - Channel1
add hl, bc
set SOUND_DUTY, [hl] ; duty cycle
; sound duty sequence
call GetMusicByte
rrca
rrca
ld hl, Channel1SFXDutyLoop - Channel1
add hl, bc
ld [hl], a
; update duty cycle
and $c0 ; only uses top 2 bits
ld hl, Channel1DutyCycle - Channel1
add hl, bc
ld [hl], a
ret
; e891e
MusicE8: ; e891e
; unused
; params: 1
ld hl, Channel1Flags2 - Channel1
add hl, bc
set SOUND_UNKN_0D, [hl]
call GetMusicByte
ld hl, Channel1Field0x2a - Channel1
add hl, bc
ld [hl], a
ret
; e892d
Music_ToggleSFX: ; e892d
; toggle something
; params: none
ld hl, Channel1Flags - Channel1
add hl, bc
bit SOUND_SFX, [hl]
jr z, .on
res SOUND_SFX, [hl]
ret
.on
set SOUND_SFX, [hl]
ret
; e893b
Music_ToggleNoise: ; e893b
; toggle music noise sampling
; can't be used as a straight toggle since the param is not read from on->off
; params:
; noise on: 1
; noise off: 0
; check if noise sampling is on
ld hl, Channel1Flags - Channel1
add hl, bc
bit SOUND_NOISE, [hl]
jr z, .on
; turn noise sampling off
res SOUND_NOISE, [hl]
ret
.on
; turn noise sampling on
set SOUND_NOISE, [hl]
call GetMusicByte
ld [MusicNoiseSampleSet], a
ret
; e894f
Music_SFXToggleNoise: ; e894f
; toggle sfx noise sampling
; params:
; on: 1
; off: 0
; check if noise sampling is on
ld hl, Channel1Flags - Channel1
add hl, bc
bit SOUND_NOISE, [hl]
jr z, .on
; turn noise sampling off
res SOUND_NOISE, [hl]
ret
.on
; turn noise sampling on
set SOUND_NOISE, [hl]
call GetMusicByte
ld [SFXNoiseSampleSet], a
ret
; e8963
Music_NoteType: ; e8963
; note length
; # frames per 16th note
; intensity: see Music_Intensity
; params: 2
; note length
call GetMusicByte
ld hl, Channel1NoteLength - Channel1
add hl, bc
ld [hl], a
ld a, [CurChannel]
and $3
cp CHAN4 ; CHAN8 & $3
ret z
; intensity
call Music_Intensity
ret
; e8977
Music_SoundStatus: ; e8977
; update sound status
; params: 1
call GetMusicByte
ld [SoundInput], a
ld hl, Channel1NoteFlags - Channel1
add hl, bc
set NOTE_UNKN_3, [hl]
ret
; e8984
Music_DutyCycle: ; e8984
; duty cycle
; params: 1
call GetMusicByte
rrca
rrca
and $c0
ld hl, Channel1DutyCycle - Channel1
add hl, bc
ld [hl], a
ret
; e8991
Music_Intensity: ; e8991
; intensity
; params: 1
; hi: pressure
; lo: velocity
call GetMusicByte
ld hl, Channel1Intensity - Channel1
add hl, bc
ld [hl], a
ret
; e899a
Music_Tempo: ; e899a
; global tempo
; params: 2
; de: tempo
call GetMusicByte
ld d, a
call GetMusicByte
ld e, a
call SetGlobalTempo
ret
; e89a6
Music_Octave8: ; e89a6
Music_Octave7: ; e89a6
Music_Octave6: ; e89a6
Music_Octave5: ; e89a6
Music_Octave4: ; e89a6
Music_Octave3: ; e89a6
Music_Octave2: ; e89a6
Music_Octave1: ; e89a6
; set octave based on lo nybble of the command
ld hl, Channel1Octave - Channel1
add hl, bc
ld a, [CurMusicByte]
and 7
ld [hl], a
ret
; e89b1
Music_ForceOctave: ; e89b1
; set starting octave
; this forces all notes up by the starting octave
; params: 1
call GetMusicByte
ld hl, Channel1StartingOctave - Channel1
add hl, bc
ld [hl], a
ret
; e89ba
Music_StereoPanning: ; e89ba
; stereo panning
; params: 1
; stereo on?
ld a, [Options]
bit 5, a ; stereo
jr nz, Music_Panning
; skip param
call GetMusicByte
ret
; e89c5
Music_Panning: ; e89c5
; force panning
; params: 1
call SetLRTracks
call GetMusicByte
ld hl, Channel1Tracks - Channel1
add hl, bc
and [hl]
ld [hl], a
ret
; e89d2
Music_Volume: ; e89d2
; set volume
; params: 1
; see Volume
; read param even if it's not used
call GetMusicByte
; is the song fading?
ld a, [MusicFade]
and a
ret nz
; reload param
ld a, [CurMusicByte]
; set volume
ld [Volume], a
ret
; e89e1
Music_TempoRelative: ; e89e1
; set global tempo to current channel tempo +- param
; params: 1 signed
call GetMusicByte
ld e, a
; check sign
cp $80
jr nc, .negative
;positive
ld d, 0
jr .ok
.negative
ld d, -1
.ok
ld hl, Channel1Tempo - Channel1
add hl, bc
ld a, [hli]
ld h, [hl]
ld l, a
add hl, de
ld e, l
ld d, h
call SetGlobalTempo
ret
; e89fd
Music_SFXPriorityOn: ; e89fd
; turn sfx priority on
; params: none
ld a, 1
ld [SFXPriority], a
ret
; e8a03
Music_SFXPriorityOff: ; e8a03
; turn sfx priority off
; params: none
xor a
ld [SFXPriority], a
ret
; e8a08
Music_RestartChannel: ; e8a08
; restart current channel from channel header (same bank)
; params: 2 (5)
; ll hh: pointer to new channel header
; header format: 0x yy zz
; x: channel # (0-3)
; zzyy: pointer to new music data
; update music id
ld hl, Channel1MusicID - Channel1
add hl, bc
ld a, [hli]
ld [MusicIDLo], a
ld a, [hl]
ld [MusicIDHi], a
; update music bank
ld hl, Channel1MusicBank - Channel1
add hl, bc
ld a, [hl]
ld [MusicBank], a
; get pointer to new channel header
call GetMusicByte
ld l, a
call GetMusicByte
ld h, a
ld e, [hl]
inc hl
ld d, [hl]
push bc ; save current channel
call LoadChannel
call StartChannel
pop bc ; restore current channel
ret
; e8a30
Music_NewSong: ; e8a30
; new song
; params: 2
; de: song id
call GetMusicByte
ld e, a
call GetMusicByte
ld d, a
push bc
call _PlayMusic
pop bc
ret
; e8a3e
GetMusicByte: ; e8a3e
; returns byte from current address in a
; advances to next byte in music data
; input: bc = start of current channel
push hl
push de
; load address into de
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld a, [hli]
ld e, a
ld d, [hl]
; load bank into a
ld hl, Channel1MusicBank - Channel1
add hl, bc
ld a, [hl]
; get byte
call _LoadMusicByte ; load data into CurMusicByte
inc de ; advance to next byte for next time this is called
; update channeldata address
ld hl, Channel1MusicAddress - Channel1
add hl, bc
ld a, e
ld [hli], a
ld [hl], d
; cleanup
pop de
pop hl
; store channeldata in a
ld a, [CurMusicByte]
ret
; e8a5d
GetFrequency: ; e8a5d
; generate frequency
; input:
; d: octave
; e: pitch
; output:
; de: frequency
; get octave
; get starting octave
ld hl, Channel1StartingOctave - Channel1
add hl, bc
ld a, [hl]
swap a ; hi nybble
and $f
; add current octave
add d
push af ; we'll use this later
; get starting octave
ld hl, Channel1StartingOctave - Channel1
add hl, bc
ld a, [hl]
and $f ; lo nybble
ld l, a ; ok
ld d, 0
ld h, d
add hl, de ; add current pitch
add hl, hl ; skip 2 bytes for each
ld de, FrequencyTable
add hl, de
ld e, [hl]
inc hl
ld d, [hl]
; get our octave
pop af
; shift right by [7 - octave] bits
.loop
; [7 - octave] loops
cp $7
jr nc, .ok
; sra de
sra d
rr e
inc a
jr .loop
.ok
ld a, d
and $7 ; top 3 bits for frequency (11 total)
ld d, a
ret
; e8a8d
SetNoteDuration: ; e8a8d
; input: a = note duration in 16ths
; store delay units in de
inc a
ld e, a
ld d, 0
; store NoteLength in a
ld hl, Channel1NoteLength - Channel1
add hl, bc
ld a, [hl]
; multiply NoteLength by delay units
ld l, 0; just multiply
call .Multiply
ld a, l ; % $100
; store Tempo in de
ld hl, Channel1Tempo - Channel1
add hl, bc
ld e, [hl]
inc hl
ld d, [hl]
; add ???? to the next result
ld hl, Channel1Field0x16 - Channel1
add hl, bc
ld l, [hl]
; multiply Tempo by last result (NoteLength * delay % $100)
call .Multiply
; copy result to de
ld e, l
ld d, h
; store result in ????
ld hl, Channel1Field0x16 - Channel1
add hl, bc
ld [hl], e
; store result in NoteDuration
ld hl, Channel1NoteDuration - Channel1
add hl, bc
ld [hl], d
ret
; e8ab8
.Multiply: ; e8ab8
; multiplies a and de
; adds the result to l
; stores the result in hl
ld h, 0
.loop
; halve a
srl a
; is there a remainder?
jr nc, .skip
; add it to the result
add hl, de
.skip
; add de, de
sla e
rl d
; are we done?
and a
jr nz, .loop
ret
; e8ac7
SetGlobalTempo: ; e8ac7
push bc ; save current channel
; are we dealing with music or sfx?
ld a, [CurChannel]
cp CHAN5
jr nc, .sfxchannels
ld bc, Channel1
call Tempo
ld bc, Channel2
call Tempo
ld bc, Channel3
call Tempo
ld bc, Channel4
call Tempo
jr .end
.sfxchannels
ld bc, Channel5
call Tempo
ld bc, Channel6
call Tempo
ld bc, Channel7
call Tempo
ld bc, Channel8
call Tempo
.end
pop bc ; restore current channel
ret
; e8b03
Tempo: ; e8b03
; input:
; de: note length
; update Tempo
ld hl, Channel1Tempo - Channel1
add hl, bc
ld [hl], e
inc hl
ld [hl], d
; clear ????
xor a
ld hl, Channel1Field0x16 - Channel1
add hl, bc
ld [hl], a
ret
; e8b11
StartChannel: ; e8b11
call SetLRTracks
ld hl, Channel1Flags - Channel1
add hl, bc
set SOUND_CHANNEL_ON, [hl] ; turn channel on
ret
; e8b1b
SetLRTracks: ; e8b1b
; set tracks for a the current channel to default
; seems to be redundant since this is overwritten by stereo data later
push de
; store current channel in de
ld a, [CurChannel]
and $3
ld e, a
ld d, 0
; get this channel's lr tracks
call GetLRTracks
add hl, de ; de = channel 0-3
ld a, [hl]
; load lr tracks into Tracks
ld hl, Channel1Tracks - Channel1
add hl, bc
ld [hl], a
pop de
ret
; e8b30
_PlayMusic:: ; e8b30
; load music
call MusicOff
ld hl, MusicID
ld [hl], e ; song number
inc hl
ld [hl], d ; MusicIDHi (always $)
ld hl, Music
add hl, de ; three
add hl, de ; byte
add hl, de ; pointer
ld a, [hli]
ld [MusicBank], a
ld e, [hl]
inc hl
ld d, [hl] ; music header address
call LoadMusicByte ; store first byte of music header in a
rlca
rlca
and $3 ; get number of channels
inc a
.loop
; start playing channels
push af
call LoadChannel
call StartChannel
pop af
dec a
jr nz, .loop
xor a
ld [wc2b5], a
ld [Channel1JumpCondition], a
ld [Channel2JumpCondition], a
ld [Channel3JumpCondition], a
ld [Channel4JumpCondition], a
ld [NoiseSampleAddressLo], a
ld [NoiseSampleAddressHi], a
ld [wNoiseSampleDelay], a
ld [MusicNoiseSampleSet], a
call MusicOn
ret
; e8b79
_PlayCryHeader:: ; e8b79
; Play cry de using parameters:
; CryPitch
; CryLength
call MusicOff
; Overload the music id with the cry id
ld hl, MusicID
ld [hl], e
inc hl
ld [hl], d
; 3-byte pointers (bank, address)
ld hl, Cries
add hl, de
add hl, de
add hl, de
ld a, [hli]
ld [MusicBank], a
ld e, [hl]
inc hl
ld d, [hl]
; Read the cry's sound header
call LoadMusicByte
; Top 2 bits contain the number of channels
rlca
rlca
and 3
; For each channel:
inc a
.loop
push af
call LoadChannel
ld hl, Channel1Flags - Channel1
add hl, bc
set SOUND_REST, [hl]
ld hl, Channel1Flags2 - Channel1
add hl, bc
set SOUND_CRY_PITCH, [hl]
ld hl, Channel1CryPitch - Channel1
add hl, bc
ld a, [CryPitch]
ld [hli], a
ld a, [CryPitch + 1]
ld [hl], a
; No tempo for channel 4
ld a, [CurChannel]
and 3
cp 3
jr nc, .start
; Tempo is effectively length
ld hl, Channel1Tempo - Channel1
add hl, bc
ld a, [CryLength]
ld [hli], a
ld a, [CryLength+1]
ld [hl], a
.start
call StartChannel
ld a, [wStereoPanningMask]
and a
jr z, .next
; Stereo only: Play cry from the monster's side.
; This only applies in-battle.
ld a, [Options]
bit 5, a ; stereo
jr z, .next
; [Tracks] &= [CryTracks]
ld hl, Channel1Tracks - Channel1
add hl, bc
ld a, [hl]
ld hl, CryTracks
and [hl]
ld hl, Channel1Tracks - Channel1
add hl, bc
ld [hl], a
.next
pop af
dec a
jr nz, .loop
; Cries play at max volume, so we save the current volume for later.
ld a, [LastVolume]
and a
jr nz, .end
ld a, [Volume]
ld [LastVolume], a
ld a, $77
ld [Volume], a
.end
ld a, 1 ; stop playing music
ld [SFXPriority], a
call MusicOn
ret
; e8c04
_PlaySFX:: ; e8c04
; clear channels if they aren't already
call MusicOff
ld hl, Channel5Flags
bit SOUND_CHANNEL_ON, [hl] ; ch5 on?
jr z, .ch6
res SOUND_CHANNEL_ON, [hl] ; turn it off
xor a
ld [rNR11], a ; length/wavepattern = 0
ld a, $8
ld [rNR12], a ; envelope = 0
xor a
ld [rNR13], a ; frequency lo = 0
ld a, $80
ld [rNR14], a ; restart sound (freq hi = 0)
xor a
ld [SoundInput], a ; global sound off
ld [rNR10], a ; sweep = 0
.ch6
ld hl, Channel6Flags
bit SOUND_CHANNEL_ON, [hl]
jr z, .ch7
res SOUND_CHANNEL_ON, [hl] ; turn it off
xor a
ld [rNR21], a ; length/wavepattern = 0
ld a, $8
ld [rNR22], a ; envelope = 0
xor a
ld [rNR23], a ; frequency lo = 0
ld a, $80
ld [rNR24], a ; restart sound (freq hi = 0)
.ch7
ld hl, Channel7Flags
bit SOUND_CHANNEL_ON, [hl]
jr z, .ch8
res SOUND_CHANNEL_ON, [hl] ; turn it off
xor a
ld [rNR30], a ; sound mode #3 off
ld [rNR31], a ; length/wavepattern = 0
ld a, $8
ld [rNR32], a ; envelope = 0
xor a
ld [rNR33], a ; frequency lo = 0
ld a, $80
ld [rNR34], a ; restart sound (freq hi = 0)
.ch8
ld hl, Channel8Flags
bit SOUND_CHANNEL_ON, [hl]
jr z, .chscleared
res SOUND_CHANNEL_ON, [hl] ; turn it off
xor a
ld [rNR41], a ; length/wavepattern = 0
ld a, $8
ld [rNR42], a ; envelope = 0
xor a
ld [rNR43], a ; frequency lo = 0
ld a, $80
ld [rNR44], a ; restart sound (freq hi = 0)
xor a
ld [NoiseSampleAddressLo], a
ld [NoiseSampleAddressHi], a
.chscleared
; start reading sfx header for # chs
ld hl, MusicID
ld [hl], e
inc hl
ld [hl], d
ld hl, SFX
add hl, de ; three
add hl, de ; byte
add hl, de ; pointers
; get bank
ld a, [hli]
ld [MusicBank], a
; get address
ld e, [hl]
inc hl
ld d, [hl]
; get # channels
call LoadMusicByte
rlca ; top 2
rlca ; bits
and $3
inc a ; # channels -> # loops
.startchannels
push af
call LoadChannel ; bc = current channel
ld hl, Channel1Flags - Channel1
add hl, bc
set SOUND_SFX, [hl]
call StartChannel
pop af
dec a
jr nz, .startchannels
call MusicOn
xor a
ld [SFXPriority], a
ret
; e8ca6
PlayStereoSFX:: ; e8ca6
; play sfx de
call MusicOff
; standard procedure if stereo's off
ld a, [Options]
bit 5, a
jp z, _PlaySFX
; else, let's go ahead with this
ld hl, MusicID
ld [hl], e
inc hl
ld [hl], d
; get sfx ptr
ld hl, SFX
add hl, de
add hl, de
add hl, de
; bank
ld a, [hli]
ld [MusicBank], a
; address
ld e, [hl]
inc hl
ld d, [hl]
; bit 2-3
call LoadMusicByte
rlca
rlca
and 3 ; ch1-4
inc a
.loop
push af
call LoadChannel
ld hl, Channel1Flags - Channel1
add hl, bc
set SOUND_SFX, [hl]
push de
; get tracks for this channel
ld a, [CurChannel]
and 3 ; ch1-4
ld e, a
ld d, 0
call GetLRTracks
add hl, de
ld a, [hl]
ld hl, wStereoPanningMask
and [hl]
ld hl, Channel1Tracks - Channel1
add hl, bc
ld [hl], a
ld hl, Channel1Field0x30 - Channel1 ; $c131 - Channel1
add hl, bc
ld [hl], a
ld a, [CryTracks]
cp 2 ; ch 1-2
jr c, .skip
; ch3-4
ld a, [wSFXDuration]
ld hl, Channel1Field0x2e - Channel1 ; $c12f - Channel1
add hl, bc
ld [hl], a
ld hl, Channel1Field0x2f - Channel1 ; $c130 - Channel1
add hl, bc
ld [hl], a
ld hl, Channel1Flags2 - Channel1
add hl, bc
set SOUND_UNKN_0F, [hl]
.skip
pop de
; turn channel on
ld hl, Channel1Flags - Channel1
add hl, bc
set SOUND_CHANNEL_ON, [hl] ; on
; done?
pop af
dec a
jr nz, .loop
; we're done
call MusicOn
ret
; e8d1b
LoadChannel: ; e8d1b
; prep channel for use
; input:
; de:
; get pointer to current channel
call LoadMusicByte
inc de
and $7 ; bit 0-2 (current channel)
ld [CurChannel], a
ld c, a
ld b, 0
ld hl, ChannelPointers
add hl, bc
add hl, bc
ld c, [hl]
inc hl
ld b, [hl] ; bc = channel pointer
ld hl, Channel1Flags - Channel1
add hl, bc
res SOUND_CHANNEL_ON, [hl] ; channel off
call ChannelInit
; load music pointer
ld hl, Channel1MusicAddress - Channel1
add hl, bc
call LoadMusicByte
ld [hli], a
inc de
call LoadMusicByte
ld [hl], a
inc de
; load music id
ld hl, Channel1MusicID - Channel1
add hl, bc
ld a, [MusicIDLo]
ld [hli], a
ld a, [MusicIDHi]
ld [hl], a
; load music bank
ld hl, Channel1MusicBank - Channel1
add hl, bc
ld a, [MusicBank]
ld [hl], a
ret
; e8d5b
ChannelInit: ; e8d5b
; make sure channel is cleared
; set default tempo and note length in case nothing is loaded
; input:
; bc = channel struct pointer
push de
xor a
; get channel struct location and length
ld hl, Channel1MusicID - Channel1 ; start
add hl, bc
ld e, Channel2 - Channel1 ; channel struct length
; clear channel
.loop
ld [hli], a
dec e
jr nz, .loop
; set tempo to default ($100)
ld hl, Channel1Tempo - Channel1
add hl, bc
xor a
ld [hli], a
inc a
ld [hl], a
; set note length to default ($1) (fast)
ld hl, Channel1NoteLength - Channel1
add hl, bc
ld [hl], a
pop de
ret
; e8d76
LoadMusicByte:: ; e8d76
; input:
; de = current music address
; output:
; a = CurMusicByte
ld a, [MusicBank]
call _LoadMusicByte
ld a, [CurMusicByte]
ret
; e8d80
FrequencyTable: ; e8d80
dw 0 ; filler
dw $f82c
dw $f89d
dw $f907
dw $f96b
dw $f9ca
dw $fa23
dw $fa77
dw $fac7
dw $fb12
dw $fb58
dw $fb9b
dw $fbda
dw $fc16
dw $fc4e
dw $fc83
dw $fcb5
dw $fce5
dw $fd11
dw $fd3b
dw $fd63
dw $fd89
dw $fdac
dw $fdcd
dw $fded
; e8db2
WaveSamples: ; e8db2
; these are streams of 32 4-bit values used as wavepatterns
; nothing interesting here!
dn 0, 2, 4, 6, 8, 10, 12, 14, 15, 15, 15, 14, 14, 13, 13, 12, 12, 11, 10, 9, 8, 7, 6, 5, 4, 4, 3, 3, 2, 2, 1, 1
dn 0, 2, 4, 6, 8, 10, 12, 14, 14, 15, 15, 15, 15, 14, 14, 14, 13, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 2, 1, 1
dn 1, 3, 6, 9, 11, 13, 14, 14, 14, 14, 15, 15, 15, 15, 14, 13, 13, 14, 15, 15, 15, 15, 14, 14, 14, 14, 13, 11, 9, 6, 3, 1
dn 0, 2, 4, 6, 8, 10, 12, 13, 14, 15, 15, 14, 13, 14, 15, 15, 14, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0
dn 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 13, 14, 14, 15, 7, 7, 15, 14, 14, 13, 12, 10, 8, 7, 6, 5, 4, 3, 2, 1, 0
dn 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 3, 3, 2, 2, 1, 1, 15, 15, 14, 14, 12, 12, 10, 10, 8, 8, 10, 10, 12, 12, 14, 14
dn 0, 2, 4, 6, 8, 10, 12, 14, 12, 11, 10, 9, 8, 7, 6, 5, 15, 15, 15, 14, 14, 13, 13, 12, 4, 4, 3, 3, 2, 2, 1, 1
dn 12, 0, 10, 9, 8, 7, 15, 5, 15, 15, 15, 14, 14, 13, 13, 12, 4, 4, 3, 3, 2, 2, 15, 1, 0, 2, 4, 6, 8, 10, 12, 14
dn 4, 4, 3, 3, 2, 2, 1, 15, 0, 0, 4, 6, 8, 10, 12, 14, 15, 8, 15, 14, 14, 13, 13, 12, 12, 11, 10, 9, 8, 7, 6, 5
dn 1, 1, 0, 0, 0, 0, 0, 8, 0, 0, 1, 3, 5, 7, 9, 10, 11, 4, 11, 10, 10, 9, 9, 8, 8, 7, 6, 5, 4, 3, 2, 1
; e8e52
Drumkits: ; e8e52
dw Drumkit0
dw Drumkit1
dw Drumkit2
dw Drumkit3
dw Drumkit4
dw Drumkit5
; e8e5e
Drumkit0: ; e8e5e
dw Drum00 ; rest
dw Snare1 ; c
dw Snare2 ; c#
dw Snare3 ; d
dw Snare4 ; d#
dw Drum05 ; e
dw Triangle1 ; f
dw Triangle2 ; f#
dw HiHat1 ; g
dw Snare5 ; g#
dw Snare6 ; a
dw Snare7 ; a#
dw HiHat2 ; b
Drumkit1: ; e8e78
dw Drum00
dw HiHat1
dw Snare5
dw Snare6
dw Snare7
dw HiHat2
dw HiHat3
dw Snare8
dw Triangle3
dw Triangle4
dw Snare9
dw Snare10
dw Snare11
Drumkit2: ; e8e92
dw Drum00
dw Snare1
dw Snare9
dw Snare10
dw Snare11
dw Drum05
dw Triangle1
dw Triangle2
dw HiHat1
dw Snare5
dw Snare6
dw Snare7
dw HiHat2
Drumkit3: ; e8eac
dw Drum21
dw Snare12
dw Snare13
dw Snare14
dw Kick1
dw Triangle5
dw Drum20
dw Drum27
dw Drum28
dw Drum29
dw Drum21
dw Kick2
dw Crash2
Drumkit4: ; e8ec6
dw Drum21
dw Drum20
dw Snare13
dw Snare14
dw Kick1
dw Drum33
dw Triangle5
dw Drum35
dw Drum31
dw Drum32
dw Drum36
dw Kick2
dw Crash1
Drumkit5: ; e8ee0
dw Drum00
dw Snare9
dw Snare10
dw Snare11
dw Drum27
dw Drum28
dw Drum29
dw Drum05
dw Triangle1
dw Crash1
dw Snare14
dw Snare13
dw Kick2
; e8efa
Drum00: ; e8efa
; unused
noise C#, 1, $11, $00
endchannel
; e8efe
Snare1: ; e8efe
noise C#, 1, $c1, $33
endchannel
; e8f02
Snare2: ; e8f02
noise C#, 1, $b1, $33
endchannel
; e8f06
Snare3: ; e8f06
noise C#, 1, $a1, $33
endchannel
; e8f0a
Snare4: ; e8f0a
noise C#, 1, $81, $33
endchannel
; e8f0e
Drum05: ; e8f0e
noise C#, 8, $84, $37
noise C#, 7, $84, $36
noise C#, 6, $83, $35
noise C#, 5, $83, $34
noise C#, 4, $82, $33
noise C#, 3, $81, $32
endchannel
; e8f21
Triangle1: ; e8f21
noise C#, 1, $51, $2a
endchannel
; e8f25
Triangle2: ; e8f25
noise C#, 2, $41, $2b
noise C#, 1, $61, $2a
endchannel
; e8f2c
HiHat1: ; e8f2c
noise C#, 1, $81, $10
endchannel
; e8f30
Snare5: ; e8f30
noise C#, 1, $82, $23
endchannel
; e8f34
Snare6: ; e8f34
noise C#, 1, $82, $25
endchannel
; e8f38
Snare7: ; e8f38
noise C#, 1, $82, $26
endchannel
; e8f3c
HiHat2: ; e8f3c
noise C#, 1, $a1, $10
endchannel
; e8f40
HiHat3: ; e8f40
noise C#, 1, $a2, $11
endchannel
; e8f44
Snare8: ; e8f44
noise C#, 1, $a2, $50
endchannel
; e8f48
Triangle3: ; e8f48
noise C#, 1, $a1, $18
noise C#, 1, $31, $33
endchannel
; e8f4f
Triangle4: ; e8f4f
noise C#, 3, $91, $28
noise C#, 1, $71, $18
endchannel
; e8f56
Snare9: ; e8f56
noise C#, 1, $91, $22
endchannel
; e8f5a
Snare10: ; e8f5a
noise C#, 1, $71, $22
endchannel
; e8f5e
Snare11: ; e8f5e
noise C#, 1, $61, $22
endchannel
; e8f62
Drum20: ; e8f62
noise C#, 1, $11, $11
endchannel
; e8f66
Drum21: ; e8f66
endchannel
; e8f67
Snare12: ; e8f67
noise C#, 1, $91, $33
endchannel
; e8f6b
Snare13: ; e8f6b
noise C#, 1, $51, $32
endchannel
; e8f6f
Snare14: ; e8f6f
noise C#, 1, $81, $31
endchannel
; e8f73
Kick1: ; e8f73
noise C#, 1, $88, $6b
noise C#, 1, $71, $00
endchannel
; e8f7a
Triangle5: ; e8f7a
noise D_, 1, $91, $18
endchannel
; e8f7e
Drum27: ; e8f7e
noise C#, 8, $92, $10
endchannel
; e8f82
Drum28: ; e8f82
noise D_, 4, $91, $00
noise D_, 4, $11, $00
endchannel
; e8f89
Drum29: ; e8f89
noise D_, 4, $91, $11
noise D_, 4, $11, $00
endchannel
; e8f90
Crash1: ; e8f90
noise D_, 4, $88, $15
noise C#, 1, $65, $12
endchannel
; e8f97
Drum31: ; e8f97
noise D_, 4, $51, $21
noise D_, 4, $11, $11
endchannel
; e8f9e
Drum32: ; e8f9e
noise D_, 4, $51, $50
noise D_, 4, $11, $11
endchannel
; e8fa5
Drum33: ; e8fa5
noise C#, 1, $a1, $31
endchannel
; e8fa9
Crash2: ; e8fa9
noise C#, 1, $84, $12
endchannel
; e8fad
Drum35: ; e8fad
noise D_, 4, $81, $00
noise D_, 4, $11, $00
endchannel
; e8fb4
Drum36: ; e8fb4
noise D_, 4, $81, $21
noise D_, 4, $11, $11
endchannel
; e8fbb
Kick2: ; e8fbb
noise C#, 1, $a8, $6b
noise C#, 1, $71, $00
endchannel
; e8fc2
GetLRTracks: ; e8fc2
; gets the default sound l/r channels
; stores mono/stereo table in hl
ld a, [Options]
bit 5, a ; stereo
; made redundant, could have had a purpose in gold
jr nz, .stereo
ld hl, MonoTracks
ret
.stereo
ld hl, StereoTracks
ret
; e8fd1
MonoTracks: ; e8fd1
; bit corresponds to track #
; hi: left channel
; lo: right channel
db $11, $22, $44, $88
; e8fd5
StereoTracks: ; e8fd5
; made redundant
; seems to be modified on a per-song basis
db $11, $22, $44, $88
; e8fd9
ChannelPointers: ; e8fd9
; music channels
dw Channel1
dw Channel2
dw Channel3
dw Channel4
; sfx channels
dw Channel5
dw Channel6
dw Channel7
dw Channel8
; e8fe9
ClearChannels:: ; e8fe9
; runs ClearChannel for all 4 channels
; doesn't seem to be used, but functionally identical to MapSetup_Sound_Off
ld hl, rNR50
xor a
ld [hli], a
ld [hli], a
ld a, $80
ld [hli], a
ld hl, rNR10
ld e, $4
.loop
call ClearChannel
dec e
jr nz, .loop
ret
; e8ffe
ClearChannel: ; e8ffe
; input: hl = beginning hw sound register (rNR10, rNR20, rNR30, rNR40)
; output: 00 00 80 00 80
; sound channel 1 2 3 4
xor a
ld [hli], a ; rNR10, rNR20, rNR30, rNR40 ; sweep = 0
ld [hli], a ; rNR11, rNR21, rNR31, rNR41 ; length/wavepattern = 0
ld a, $8
ld [hli], a ; rNR12, rNR22, rNR32, rNR42 ; envelope = 0
xor a
ld [hli], a ; rNR13, rNR23, rNR33, rNR43 ; frequency lo = 0
ld a, $80
ld [hli], a ; rNR14, rNR24, rNR34, rNR44 ; restart sound (freq hi = 0)
ret
; e900a