Identified two magic numbers and cleaned up some comments (#783)

Improve the audio engine's comments and replace some magic numbers with constants

audio/engine.asm

@@ -101,7 +101,7 @@ _UpdateSound::
 	ld hl, CHANNEL_NOTE_DURATION
 	add hl, bc
 	ld a, [hl]
-	cp $2 ; 1 or 0?
+	cp 2 ; 1 or 0?
 	jr c, .noteover
 	dec [hl]
 	jr .continue_sound_update
@@ -212,7 +212,7 @@ _UpdateSound::
 UpdateChannels:
 	ld hl, .ChannelFnPtrs
 	ld a, [wCurChannel]
-	and $7
+	maskbits NUM_CHANNELS
 	add a
 	ld e, a
 	ld d, 0
@@ -1141,7 +1141,6 @@ ParseMusic:
 	jr z, .sound_ret
 	cp FIRST_MUSIC_CMD
 	jr c, .readnote
-	; then it's a command
 .readcommand
 	call ParseMusicCommand
 	jr ParseMusic ; start over
@@ -1366,39 +1365,39 @@ ParseMusicCommand:
 
 MusicCommands:
 ; entries correspond to audio constants (see macros/scripts/audio.asm)
-	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_Octave8
+	dw Music_Octave7
+	dw Music_Octave6
+	dw Music_Octave5
+	dw Music_Octave4
+	dw Music_Octave3
+	dw Music_Octave2
+	dw Music_Octave1
 	dw Music_NoteType ; note length + volume envelope
-	dw Music_Transpose ; transpose
-	dw Music_Tempo ; tempo
-	dw Music_DutyCycle ; duty cycle
-	dw Music_VolumeEnvelope ; volume envelope
-	dw Music_PitchSweep ; update pitch sweep
-	dw Music_DutyCyclePattern ; duty cycle pattern
-	dw Music_ToggleSFX ; sound on/off
-	dw Music_PitchSlide ; pitch slide
-	dw Music_Vibrato ; vibrato
+	dw Music_Transpose 
+	dw Music_Tempo
+	dw Music_DutyCycle
+	dw Music_VolumeEnvelope 
+	dw Music_PitchSweep
+	dw Music_DutyCyclePattern
+	dw Music_ToggleSFX 
+	dw Music_PitchSlide 
+	dw Music_Vibrato 
 	dw MusicE2 ; unused
-	dw Music_ToggleNoise ; music noise sampling
-	dw Music_ForceStereoPanning ; force stereo panning
-	dw Music_Volume ; volume
-	dw Music_PitchOffset ; pitch offset
+	dw Music_ToggleNoise 
+	dw Music_ForceStereoPanning 
+	dw Music_Volume 
+	dw Music_PitchOffset 
 	dw MusicE7 ; unused
 	dw MusicE8 ; unused
-	dw Music_TempoRelative ; tempo adjust
-	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 Music_TempoRelative
+	dw Music_RestartChannel
+	dw Music_NewSong 
+	dw Music_SFXPriorityOn 
+	dw Music_SFXPriorityOff 
 	dw MusicEE ; unused
-	dw Music_StereoPanning ; stereo panning
-	dw Music_SFXToggleNoise ; sfx noise sampling
+	dw Music_StereoPanning 
+	dw Music_SFXToggleNoise
 	dw MusicF1 ; nothing
 	dw MusicF2 ; nothing
 	dw MusicF3 ; nothing
@@ -1408,12 +1407,12 @@ MusicCommands:
 	dw MusicF7 ; nothing
 	dw MusicF8 ; nothing
 	dw MusicF9 ; unused
-	dw Music_SetCondition ; set condition
-	dw Music_JumpIf ; jumpif
-	dw Music_Jump ; jump
-	dw Music_Loop ; loop
-	dw Music_Call ; call
-	dw Music_Ret ; return
+	dw Music_SetCondition 
+	dw Music_JumpIf
+	dw Music_Jump
+	dw Music_Loop
+	dw Music_Call
+	dw Music_Ret
 
 MusicF1:
 MusicF2:
@@ -2107,29 +2106,23 @@ GetMusicByte:
 ; input: bc = start of current channel
 	push hl
 	push de
-	; load address into de
 	ld hl, CHANNEL_MUSIC_ADDRESS
 	add hl, bc
 	ld a, [hli]
 	ld e, a
 	ld d, [hl]
-	; load bank into a
 	ld hl, CHANNEL_MUSIC_BANK
 	add hl, bc
 	ld a, [hl]
-	; get byte
-	call _LoadMusicByte ; load data into wCurMusicByte
+	call _LoadMusicByte ; load data into [wCurMusicByte]
 	inc de ; advance to next byte for next time this is called
-	; update channeldata address
 	ld hl, CHANNEL_MUSIC_ADDRESS
 	add hl, bc
 	ld a, e
 	ld [hli], a
 	ld [hl], d
-	; cleanup
 	pop de
 	pop hl
-	; store channeldata in a
 	ld a, [wCurMusicByte]
 	ret
 
@@ -2191,7 +2184,6 @@ SetNoteDuration:
 	inc a
 	ld e, a
 	ld d, 0
-	; store NoteLength in a
 	ld hl, CHANNEL_NOTE_LENGTH
 	add hl, bc
 	ld a, [hl]
@@ -2306,7 +2298,6 @@ SetLRTracks:
 	maskbits NUM_MUSIC_CHANS
 	ld e, a
 	ld d, 0
-	; get this channel's lr tracks
 	call GetLRTracks
 	add hl, de ; de = channel 0-3
 	ld a, [hl]
@@ -2396,7 +2387,7 @@ _PlayCry::
 	inc a
 .loop
 	push af
-	call LoadChannel
+	call LoadChannel ; bc = current channel
 
 	ld hl, CHANNEL_FLAGS1
 	add hl, bc
@@ -2439,7 +2430,7 @@ _PlayCry::
 	bit STEREO, a
 	jr z, .next
 
-; [Tracks] &= [wCryTracks]
+; [CHANNEL_TRACKS] &= [wCryTracks]
 	ld hl, CHANNEL_TRACKS
 	add hl, bc
 	ld a, [hl]
@@ -2671,13 +2662,11 @@ PlayStereoSFX::
 	ret
 
 LoadChannel:
-; prep channel for use
-; input:
-; 	de:
-	; get pointer to current channel
+; input: de = audio pointer
+; sets bc to current channel pointer
 	call LoadMusicByte
 	inc de
-	and $7 ; bit 0-2 (current channel)
+	maskbits NUM_CHANNELS
 	ld [wCurChannel], a
 	ld c, a
 	ld b, 0

engine/pokedex/pokedex.asm

@@ -374,7 +374,7 @@ Pokedex_UpdateDexEntryScreen:
 	ld a, [wLastVolume]
 	and a
 	jr z, .max_volume
-	ld a, $77
+	ld a, MAX_VOLUME
 	ld [wLastVolume], a
 
 .max_volume

home/audio.asm

@@ -49,7 +49,7 @@ UpdateSound::
 	ret
 
 _LoadMusicByte::
-; wCurMusicByte = [a:de]
+; [wCurMusicByte] = [a:de]
 	ldh [hROMBank], a
 	ld [MBC3RomBank], a