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|
;****************************************************************************
; PlayBGM [command $04]
; Plays a BGM
;****************************************************************************
PlayBGM:
PollPCM
call ClearBGM ; Clear BGM resources
PollPCM
ld a, (RAM_Status) ; Show BGM playback in Echo's status
or $02
ld (RAM_Status), a
PollPCM
ld hl, RAM_ComBank ; Get command parameters
ld c, (hl)
inc l
ld e, (hl)
inc l
ld d, (hl)
PollPCM
xor a ; Command parsed
ld (RAM_Command), a
ld hl, RAM_BGMData ; Set BGM as playing
ld (hl), $01
inc l ; No delays!
ld (hl), $01
inc l ; Store BGM start bank
ld (hl), c
inc l ; Store BGM start address (low)
ld (hl), e
inc l ; Store BGM start address (high)
ld (hl), d
PollPCM
ld hl, ProcessBGM ; Tell Echo to process BGM
ld (DoTick_BGM+1), hl
PollPCM
jp IdleLoop ; End of subroutine
;****************************************************************************
; ProcessBGM
; Processes a tick for a BGM
;****************************************************************************
ProcessBGM:
PollPCM
ld hl, RAM_BGMData+1 ; BGM data address
ld a, (hl) ; Delaying?
dec a
jp z, .nodelay
ld (hl), a
jp DoTick_BGMSkip ; End of subroutine
.nodelay:
PollPCM
inc l
ld c, (hl) ; Get current address
inc l
ld e, (hl)
inc l
ld d, (hl)
ex de, hl
ProcessBGMRun:
PollPCM ; Fetch next event
call GetParam
PollPCM
ld a, b ; Parse byte
cp $08
jp c, NoteOnFMBGM ; Events $00-$07: note on FM
cp $0B
jp c, NoteOnPSGBGM ; Events $08-$0A: note on PSG (square)
jp z, NoteOnNoiseBGM ; Event $0B: note on PSG (noise)
cp $0C
jp z, PlayPCMBGM ; Event $0C: play PCM
PollPCM
ld a, b
cp $18
jp c, NoteOffFMBGM ; Events $10-$17: note off FM
cp $1C
jp c, NoteOffPSGBGM ; Events $18-$1B: note off PSG
jp z, StopPCMBGM ; Event $1C: note off PCM
PollPCM
ld a, b
cp $FE
jp z, SetDelayBGM ; Event $FE: set delay
cp $FF
jp z, StopBGMEvent ; Event $FF: stop BGM
cp $FC
jp z, LoopBGM ; Event $FC: loop BGM
cp $FD
jp z, SetLoopBGM ; Event $FD: set loop point
PollPCM
ld a, b
cp $28
jp c, SetFMVolBGM ; Events $28-$2B: set FM volume
cp $2C
jp c, SetPSGVolBGM ; Events $28-$2B: set PSG volume
PollPCM
ld a, b
cp $38
jp c, SetNoteFMBGM ; Events $30-$37: set FM note
cp $3B
jp c, SetNotePSGBGM ; Events $38-$3A: set PSG note (square)
jp z, SetNoteNoiseBGM ; Event $3B: set PSG note (noise)
PollPCM
ld a, b
cp $48
jp c, LoadFMBGM ; Events $40-$47: load FM instrument
cp $4C
jp c, LoadPSGBGM ; Events $48-$4B: load PSG instrument
PollPCM
ld a, b
cp $F8 ; Events $F0-$F7: set FM parameters
jp c, SetFMParamBGM
PollPCM ; FFFFFFFFF bad event >:(
jp StopBGMEvent ; End of subroutine
ProcessBGMSkip2: ; This is where we land after a locked event
PollPCM ; that had two bytes for the parameter
inc l ; Skip first byte
jp nz, .nobankskip2
inc h
jp nz, .nobankskip2
ld h, $80
inc c
.nobankskip2:
ProcessBGMSkip1: ; This is where we land after a locked event
PollPCM ; that had one byte for the parameter
inc l ; Skip byte
jp nz, .nobankskip1
inc h
jp nz, .nobankskip1
ld h, $80
inc c
.nobankskip1:
ProcessBGMSkip: ; This is where we land after a locked event
PollPCM ; without parameters
jp ProcessBGMRun ; Keep processing
;****************************************************************************
; StopBGM* [command $05, event $FF]
; Stops BGM playback
;****************************************************************************
StopBGMEvent:
call StopBGM ; We're just a wrapper
jp DoTick_BGMSkip ; End of subroutine
StopBGMCmd:
xor a ; Command parsed
ld (RAM_Command), a
call StopBGM ; We're just a wrapper
jp IdleLoop ; End of subroutine
StopBGM:
ld a, (RAM_Status) ; Hide BGM playback in Echo's status
and $FD
ld (RAM_Status), a
PollPCM
call ClearBGM ; Clear BGM resources
PollPCM
xor a ; Stop playback
ld (RAM_BGMPlaying), a
ld hl, DoTick_BGMSkip
ld (DoTick_BGM+1), hl
ret ; End of subroutine
;****************************************************************************
; ClearBGM
; Clears BGM resources
;****************************************************************************
ClearBGM:
ld a, (RAM_Locked+6) ; Stop PCM playback if needed
or a
call z, StopPCM
;----------------------------------------------------------------------------
ld b, 4 ; Reset all PSG channels
ld de, RAM_PSGData+48+15
ld hl, RAM_Locked+11
.mutepsg:
PollPCM
ld (hl), $00 ; Reset BGM volume
ld a, e
sub 15
ld e, a
ld a, (hl) ; Mute PSG channel if it isn't locked
or a
jr nz, .nopsgmute
xor a
ld (de), a
.nopsgmute:
PollPCM
dec e
dec l
djnz .mutepsg
;----------------------------------------------------------------------------
ld b, 8 ; Reset all FM channels
ld de, RAM_BGMFMVol+7
.resetfm:
PollPCM
xor a ; Reset BGM volume
ld (de), a
dec e
ld a, (hl) ; Kill FM channel if not locked
or a
jp nz, .nofmkill
PollPCM
ld a, b
dec a
call KillFM
.nofmkill:
dec l
djnz .resetfm
;----------------------------------------------------------------------------
ret ; End of subroutine
;****************************************************************************
; LoopBGM [event $FC]
; Makes a BGM loop
;****************************************************************************
LoopBGM:
PollPCM
ex de, hl ; Get looping address
inc l
ld c, (hl)
inc l
ld e, (hl)
inc l
ld d, (hl)
dec l
dec l
dec l
ex de, hl
jp ProcessBGMRun ; End of subroutine
;****************************************************************************
; SetLoopBGM [event $FD]
; Sets the BGM loop point
;****************************************************************************
SetLoopBGM:
PollPCM
ex de, hl
inc l ; Store loop point address
ld (hl), c
inc l
ld (hl), e
inc l
ld (hl), d
dec l
dec l
dec l
ex de, hl
jp ProcessBGMRun ; End of subroutine
|
