BROKEN: add more channel editing to music player

Ch1+Ch2 duty cycle in progress, Noise set to-do
Bug: holding up/down eventually crashes, in BGB and VBA, even on the Tempo's dummy case

musicplayer.asm

@@ -411,13 +411,96 @@ SongEditor:
 	jp SongEditor
 
 .up:
+; for ch1/ch2: next duty cycle
 ; for wave: next waveform
+; for noise: next noise set
 ; for pitch: increase pitch transposition
 	ld a, [wChannelSelector]
-	cp MP_EDIT_PITCH
-	jr z, .up_pitch
-	cp MP_EDIT_WAVE
-	jp nz, SongEditor
+	ld hl, .up_jumptable
+	rst JumpTable
+
+.up_jumptable
+	dw .up_ch1_2  ; MP_EDIT_CH1
+	dw .up_ch1_2  ; MP_EDIT_CH2
+	dw .up_wave   ; MP_EDIT_WAVE
+	dw .up_noise  ; MP_EDIT_NOISE
+	dw .up_pitch  ; MP_EDIT_PITCH
+	dw SongEditor ; MP_EDIT_TEMPO
+
+.down:
+; for ch1/ch2: previous duty cycle
+; for wave: previous waveform
+; for noise: previous noise set
+; for pitch: decrease pitch transposition
+	ld a, [wChannelSelector]
+	ld hl, .down_jumptable
+	rst JumpTable
+
+.down_jumptable:
+	dw .down_ch1_2 ; MP_EDIT_CH1
+	dw .down_ch1_2 ; MP_EDIT_CH2
+	dw .down_wave  ; MP_EDIT_WAVE
+	dw .down_noise ; MP_EDIT_NOISE
+	dw .down_pitch ; MP_EDIT_PITCH
+	dw SongEditor  ; MP_EDIT_TEMPO
+
+.start:
+; toggle piano roll info overlay
+	ld hl, wSongInfoSwitch
+	ld a, [hl]
+	xor 1
+	ld [hl], a
+	call DrawPianoRollOverlay
+	jp SongEditor
+
+.select_b:
+; exit song editor
+	call ClearChannelSelector
+	xor a ; ld a, MP_EDIT_CH1
+	ld [wChannelSelector], a
+	call DrawPitchTransposition
+	call DrawTempoAdjustment
+	jp MusicPlayerLoop
+
+.up_ch1_2:
+; next duty cycle
+	ld a, [wChannelSelector]
+	ld [wTmpCh], a
+	call GetDutyCycleAddr
+	ld a, [hl]
+	lb bc, %11000000, %01000000
+	and b
+	cp b
+	ld a, [hl]
+	jr nz, .no_ch1_2_overflow
+	sub c
+	and %00111111
+.no_ch1_2_overflow
+	add c
+	jr .change_ch1_2
+
+.down_ch1_2:
+; previous duty cycle
+	ld a, [wChannelSelector]
+	ld [wTmpCh], a
+	call GetDutyCycleAddr
+	ld a, [hl]
+	lb bc, %11000000, %01000000
+	and b
+	and a
+	ld a, [hl]
+	jr nz, .no_ch1_2_underflow
+	add c
+	and %00111111
+.no_ch1_2_underflow
+	sub c
+.change_ch1_2:
+	ld [hl], a
+	ld [wCurTrackDuty], a
+	jp SongEditor
+
+.up_wave:
+; next waveform
 	ld a, [Channel3Intensity]
 	and $f
 	inc a
@@ -426,14 +509,8 @@ SongEditor:
 	xor a
 	jr .change_wave
 
-.down:
-; for wave: previous waveform
-; for pitch: decrease pitch transposition
-	ld a, [wChannelSelector]
-	cp MP_EDIT_PITCH
-	jr z, .down_pitch
-	cp MP_EDIT_WAVE
-	jp nz, SongEditor
+.down_wave:
+; previous waveform
 	ld a, [Channel3Intensity]
 	and $f
 	dec a
@@ -450,7 +527,15 @@ SongEditor:
 	farcall ReloadWaveform
 	jp SongEditor
 
+; TODO: up/down for noise adjusts MusicNoiseSampleSet
+.up_noise:
+; next noise set
+.down_noise:
+; previous noise set
+	jp SongEditor
+
 .up_pitch:
+; increase pitch transposition
 	ld a, [wPitchTransposition]
 	inc a
 	cp MAX_PITCH_TRANSPOSITION + 1
@@ -459,6 +544,7 @@ SongEditor:
 	jr .change_pitch
 
 .down_pitch:
+; decrease pitch transposition
 	ld a, [wPitchTransposition]
 	dec a
 	cp -(MAX_PITCH_TRANSPOSITION + 1)
@@ -473,24 +559,6 @@ SongEditor:
 	call DelayFrame
 	jp SongEditor
 
-.start:
-; toggle piano roll info overlay
-	ld hl, wSongInfoSwitch
-	ld a, [hl]
-	xor 1
-	ld [hl], a
-	call DrawPianoRollOverlay
-	jp SongEditor
-
-.select_b:
-; exit song editor
-	call ClearChannelSelector
-	xor a ; ld a, MP_EDIT_CH1
-	ld [wChannelSelector], a
-	call DrawPitchTransposition
-	call DrawTempoAdjustment
-	jp MusicPlayerLoop
-
 AdjustTempo:
 	ld a, 1
 	ld [wAdjustingTempo], a
@@ -1372,25 +1440,17 @@ endr
 	ret
 
 GetPitchAddr:
-	ld a, [wTmpCh]
-	add a
-	ld hl, PitchAddrs
-	ld c, a
-	ld b, 0
-	add hl, bc
-	ld a, [hli]
-	ld h, [hl]
-	ld l, a
-	ret
-
-PitchAddrs:
-	dw Channel1Pitch
-	dw Channel2Pitch
-	dw Channel3Pitch
+	ld hl, Channel1Pitch
+	jr _GetChannelMemberAddr
 
 GetOctaveAddr:
-	ld a, [wTmpCh]
 	ld hl, Channel1Octave
+	jr _GetChannelMemberAddr
+
+GetDutyCycleAddr:
+	ld hl, Channel1DutyCycle
+_GetChannelMemberAddr:
+	ld a, [wTmpCh]
 	ld bc, Channel2 - Channel1
 	jp AddNTimes
 
@@ -1400,12 +1460,6 @@ GetIntensityAddr:
 	ld bc, 2
 	jp AddNTimes
 
-GetDutyCycleAddr:
-	ld a, [wTmpCh]
-	ld hl, Channel1DutyCycle
-	ld bc, Channel2 - Channel1
-	jp AddNTimes
-
 GetSongInfo:
 	ld a, [wSongSelection]
 	ld b, a