FM-TOWNS AUDIO: fix thread lockups and cleanup

- fixed lockup situation in imuse destructor (only concerning the fm-towns driver)
- fixed lockup situation when AudioCDManager functions get called
(in both cases both the main thread and the mixer thread would get locked in different mutex belonging to the other thread)

7 files changed, 284 insertions, 244 deletions

diff --git a/audio/softsynth/fmtowns_pc98/towns_audio.cpp b/audio/softsynth/fmtowns_pc98/towns_audio.cpp
index 719bc981ee..635f9354cc 100644
--- a/audio/softsynth/fmtowns_pc98/towns_audio.cpp
+++ b/audio/softsynth/fmtowns_pc98/towns_audio.cpp
@@ -30,7 +30,7 @@
 
 
 class TownsAudio_PcmChannel {
-friend class TownsAudioInterfaceIntern;
+friend class TownsAudioInterfaceInternal;
 public:
 	TownsAudio_PcmChannel();
 	~TownsAudio_PcmChannel();
@@ -80,7 +80,7 @@ private:
 };
 
 class TownsAudio_WaveTable {
-friend class TownsAudioInterfaceIntern;
+friend class TownsAudioInterfaceInternal;
 public:
 	TownsAudio_WaveTable();
 	~TownsAudio_WaveTable();
@@ -101,12 +101,12 @@ private:
 	int8 *data;
 };
 
-class TownsAudioInterfaceIntern : public TownsPC98_FmSynth {
+class TownsAudioInterfaceInternal : public TownsPC98_FmSynth {
 public:
-	TownsAudioInterfaceIntern(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver);
-	~TownsAudioInterfaceIntern();
+	TownsAudioInterfaceInternal(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver);
+	~TownsAudioInterfaceInternal();
 
-	static TownsAudioInterfaceIntern *addNewRef(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver);
+	static TownsAudioInterfaceInternal *addNewRef(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver);
 	static void releaseRef();
 	bool checkPluginDriver(TownsAudioInterfacePluginDriver *driver);
 
@@ -127,7 +127,7 @@ private:
 	void timerCallbackA();
 	void timerCallbackB();
 
-	typedef int (TownsAudioInterfaceIntern::*TownsAudioIntfCallback)(va_list &);
+	typedef int (TownsAudioInterfaceInternal::*TownsAudioIntfCallback)(va_list &);
 	const TownsAudioIntfCallback *_intfOpcodes;
 
 	int intf_reset(va_list &args);
@@ -223,9 +223,11 @@ private:
 	void pcmCalcPhaseStep(TownsAudio_PcmChannel *p, TownsAudio_WaveTable *w);
 
 	void updateOutputVolume();
+	void updateOutputVolumeInternal();
 	uint8 _outputVolumeFlags;
 	uint8 _outputLevel[16];
 	uint8 _outputMute[16];
+	bool _updateOutputVol;
 
 	const float _baserate;
 	uint32 _timerBase;
@@ -239,7 +241,7 @@ private:
 	TownsAudioInterfacePluginDriver *_drv;
 	bool _ready;
 
-	static TownsAudioInterfaceIntern *_refInstance;
+	static TownsAudioInterfaceInternal *_refInstance;
 	static int _refCount;
 
 	static const uint8 _chanFlags[];
@@ -250,15 +252,15 @@ private:
 	static const uint16 _pcmPhase2[];
 };
 
-TownsAudioInterfaceIntern::TownsAudioInterfaceIntern(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver) : TownsPC98_FmSynth(mixer, kTypeTowns),
+TownsAudioInterfaceInternal::TownsAudioInterfaceInternal(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver) : TownsPC98_FmSynth(mixer, kTypeTowns),
 	_fmInstruments(0), _pcmInstruments(0), _pcmChan(0), _waveTables(0), _waveTablesTotalDataSize(0),
 	_baserate(55125.0f / (float)mixer->getOutputRate()), _tickLength(0), _timer(0), _drv(driver),
 	_pcmSfxChanMask(0),	_musicVolume(Audio::Mixer::kMaxMixerVolume), _sfxVolume(Audio::Mixer::kMaxMixerVolume),
 	_outputVolumeFlags(0), _pcmChanOut(0), _pcmChanReserved(0), _pcmChanKeyPressed(0),
 	_pcmChanEffectPlaying(0), _pcmChanKeyPlaying(0), _fmChanPlaying(0), 
-	_numReservedChannels(0), _numWaveTables(0), _ready(false) {
+	_numReservedChannels(0), _numWaveTables(0), _updateOutputVol(false), _ready(false) {
 
-#define INTCB(x) &TownsAudioInterfaceIntern::intf_##x
+#define INTCB(x) &TownsAudioInterfaceInternal::intf_##x
 	static const TownsAudioIntfCallback intfCb[] = {
 		// 0
 		INTCB(reset),
@@ -381,7 +383,7 @@ TownsAudioInterfaceIntern::TownsAudioInterfaceIntern(Audio::Mixer *mixer, TownsA
 	_tickLength = 2 * _timerBase;
 }
 
-TownsAudioInterfaceIntern::~TownsAudioInterfaceIntern() {
+TownsAudioInterfaceInternal::~TownsAudioInterfaceInternal() {
 	_ready = false;
 	deinit();
 
@@ -393,19 +395,19 @@ TownsAudioInterfaceIntern::~TownsAudioInterfaceIntern() {
 	delete[] _pcmChan;
 }
 
-TownsAudioInterfaceIntern *TownsAudioInterfaceIntern::addNewRef(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver) {
+TownsAudioInterfaceInternal *TownsAudioInterfaceInternal::addNewRef(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver) {
 	_refCount++;
 	if (_refCount == 1 && _refInstance == 0)
-		_refInstance = new TownsAudioInterfaceIntern(mixer, driver);
+		_refInstance = new TownsAudioInterfaceInternal(mixer, driver);
 	else if (_refCount < 2 || _refInstance == 0)
-		error("TownsAudioInterfaceIntern::addNewRef(): Internal reference management failure");
+		error("TownsAudioInterfaceInternal::addNewRef(): Internal reference management failure");
 	else if (!_refInstance->checkPluginDriver(driver))
-		error("TownsAudioInterfaceIntern::addNewRef(): Plugin driver conflict");
+		error("TownsAudioInterfaceInternal::addNewRef(): Plugin driver conflict");
 
 	return _refInstance;
 }
 
-void TownsAudioInterfaceIntern::releaseRef() {
+void TownsAudioInterfaceInternal::releaseRef() {
 	if (!_refCount)
 		return;
 
@@ -417,7 +419,7 @@ void TownsAudioInterfaceIntern::releaseRef() {
 	}
 }
 
-bool TownsAudioInterfaceIntern::checkPluginDriver(TownsAudioInterfacePluginDriver *driver) {
+bool TownsAudioInterfaceInternal::checkPluginDriver(TownsAudioInterfacePluginDriver *driver) {
 	if (_refCount <= 1)
 		return true;
 
@@ -425,15 +427,13 @@ bool TownsAudioInterfaceIntern::checkPluginDriver(TownsAudioInterfacePluginDrive
 		if (driver && driver != _drv)
 			return false;
 	} else {
-		lock();
 		_drv = driver;
-		unlock();
 	}
 
 	return true;
 }
 
-bool TownsAudioInterfaceIntern::init() {
+bool TownsAudioInterfaceInternal::init() {
 	if (_ready)
 		return true;
 
@@ -457,7 +457,7 @@ bool TownsAudioInterfaceIntern::init() {
 	return true;
 }
 
-int TownsAudioInterfaceIntern::callback(int command, ...) {
+int TownsAudioInterfaceInternal::callback(int command, ...) {
 	if (!_ready)
 		return 1;
 
@@ -470,40 +470,42 @@ int TownsAudioInterfaceIntern::callback(int command, ...) {
 	return res;
 }
 
-int TownsAudioInterfaceIntern::processCommand(int command, va_list &args) {
+int TownsAudioInterfaceInternal::processCommand(int command, va_list &args) {
 	if (!_ready)
 		return 1;
 
 	if (command < 0 || command > 81)
 		return 4;
 	
-	lock();
+	Common::StackLock lock(_mutex);
 	int res = (this->*_intfOpcodes[command])(args);
-	unlock();
 
 	return res;
 }
 
-void TownsAudioInterfaceIntern::setMusicVolume(int volume) {
+void TownsAudioInterfaceInternal::setMusicVolume(int volume) {
 	_musicVolume = CLIP<uint16>(volume, 0, Audio::Mixer::kMaxMixerVolume);
 	setVolumeIntern(_musicVolume, _sfxVolume);
 }
 
-void TownsAudioInterfaceIntern::setSoundEffectVolume(int volume) {
+void TownsAudioInterfaceInternal::setSoundEffectVolume(int volume) {
 	_sfxVolume = CLIP<uint16>(volume, 0, Audio::Mixer::kMaxMixerVolume);
 	setVolumeIntern(_musicVolume, _sfxVolume);
 }
 
-void TownsAudioInterfaceIntern::setSoundEffectChanMask(int mask) {
+void TownsAudioInterfaceInternal::setSoundEffectChanMask(int mask) {
 	_pcmSfxChanMask = mask >> 6;
 	mask &= 0x3f;
 	setVolumeChannelMasks(~mask, mask);
 }
 
-void TownsAudioInterfaceIntern::nextTickEx(int32 *buffer, uint32 bufferSize) {
+void TownsAudioInterfaceInternal::nextTickEx(int32 *buffer, uint32 bufferSize) {
 	if (!_ready)
 		return;
 
+	if (_updateOutputVol)
+		updateOutputVolumeInternal();
+
 	for (uint32 i = 0; i < bufferSize; i++) {
 		_timer += _tickLength;
 		while (_timer > 0x514767) {
@@ -551,12 +553,12 @@ void TownsAudioInterfaceIntern::nextTickEx(int32 *buffer, uint32 bufferSize) {
 	}
 }
 
-void TownsAudioInterfaceIntern::timerCallbackA() {
+void TownsAudioInterfaceInternal::timerCallbackA() {
 	if (_drv && _ready)
 		_drv->timerCallback(0);
 }
 
-void TownsAudioInterfaceIntern::timerCallbackB() {
+void TownsAudioInterfaceInternal::timerCallbackB() {
 	if (_ready) {
 		if (_drv)
 			_drv->timerCallback(1);
@@ -564,62 +566,62 @@ void TownsAudioInterfaceIntern::timerCallbackB() {
 	}
 }
 
-int TownsAudioInterfaceIntern::intf_reset(va_list &args) {
+int TownsAudioInterfaceInternal::intf_reset(va_list &args) {
 	fmReset();
 	pcmReset();
 	callback(68);
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_keyOn(va_list &args) {
+int TownsAudioInterfaceInternal::intf_keyOn(va_list &args) {
 	int chan = va_arg(args, int);
 	int note = va_arg(args, int);
 	int velo = va_arg(args, int);
 	return (chan & 0x40) ? pcmKeyOn(chan, note, velo) : fmKeyOn(chan, note, velo);
 }
 
-int TownsAudioInterfaceIntern::intf_keyOff(va_list &args) {
+int TownsAudioInterfaceInternal::intf_keyOff(va_list &args) {
 	int chan = va_arg(args, int);
 	return (chan & 0x40) ? pcmKeyOff(chan) : fmKeyOff(chan);
 }
 
-int TownsAudioInterfaceIntern::intf_setPanPos(va_list &args) {
+int TownsAudioInterfaceInternal::intf_setPanPos(va_list &args) {
 	int chan = va_arg(args, int);
 	int mode = va_arg(args, int);
 	return (chan & 0x40) ? pcmSetPanPos(chan, mode) : fmSetPanPos(chan, mode);
 }
 
-int TownsAudioInterfaceIntern::intf_setInstrument(va_list &args) {
+int TownsAudioInterfaceInternal::intf_setInstrument(va_list &args) {
 	int chan = va_arg(args, int);
 	int instrId = va_arg(args, int);
 	return (chan & 0x40) ? pcmSetInstrument(chan, instrId) : fmSetInstrument(chan, instrId);
 }
 
-int TownsAudioInterfaceIntern::intf_loadInstrument(va_list &args) {
+int TownsAudioInterfaceInternal::intf_loadInstrument(va_list &args) {
 	int chanType = va_arg(args, int);
 	int instrId = va_arg(args, int);
 	uint8 *instrData = va_arg(args, uint8 *);
 	return (chanType & 0x40) ? pcmLoadInstrument(instrId, instrData) : fmLoadInstrument(instrId, instrData);
 }
 
-int TownsAudioInterfaceIntern::intf_setPitch(va_list &args) {
+int TownsAudioInterfaceInternal::intf_setPitch(va_list &args) {
 	int chan = va_arg(args, int);
 	int16 pitch = (int16)(va_arg(args, int) & 0xffff);
 	return (chan & 0x40) ? pcmSetPitch(chan, pitch) : fmSetPitch(chan, pitch);
 }
 
-int TownsAudioInterfaceIntern::intf_setLevel(va_list &args) {
+int TownsAudioInterfaceInternal::intf_setLevel(va_list &args) {
 	int chan = va_arg(args, int);
 	int lvl = va_arg(args, int);
 	return (chan & 0x40) ? pcmSetLevel(chan, lvl) : fmSetLevel(chan, lvl);
 }
 
-int TownsAudioInterfaceIntern::intf_chanOff(va_list &args) {
+int TownsAudioInterfaceInternal::intf_chanOff(va_list &args) {
 	int chan = va_arg(args, int);
 	return (chan & 0x40) ? pcmChanOff(chan) : fmChanOff(chan);
 }
 
-int TownsAudioInterfaceIntern::intf_writeReg(va_list &args) {
+int TownsAudioInterfaceInternal::intf_writeReg(va_list &args) {
 	int part = va_arg(args, int) ? 1 : 0;
 	int reg = va_arg(args, int);
 	int val = va_arg(args, int);
@@ -630,7 +632,7 @@ int TownsAudioInterfaceIntern::intf_writeReg(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_writeRegBuffer(va_list &args) {
+int TownsAudioInterfaceInternal::intf_writeRegBuffer(va_list &args) {
 	int part = va_arg(args, int) ? 1 : 0;
 	int reg = va_arg(args, int);
 	int val = va_arg(args, int);
@@ -642,7 +644,7 @@ int TownsAudioInterfaceIntern::intf_writeRegBuffer(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_readRegBuffer(va_list &args) {
+int TownsAudioInterfaceInternal::intf_readRegBuffer(va_list &args) {
 	int part = va_arg(args, int) ? 1 : 0;
 	int reg = va_arg(args, int);
 	uint8 *dst = va_arg(args, uint8 *);
@@ -655,7 +657,7 @@ int TownsAudioInterfaceIntern::intf_readRegBuffer(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_setTimerA(va_list &args) {
+int TownsAudioInterfaceInternal::intf_setTimerA(va_list &args) {
 	int enable = va_arg(args, int);
 	int tempo = va_arg(args, int);
 
@@ -670,7 +672,7 @@ int TownsAudioInterfaceIntern::intf_setTimerA(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_setTimerB(va_list &args) {
+int TownsAudioInterfaceInternal::intf_setTimerB(va_list &args) {
 	int enable = va_arg(args, int);
 	int tempo = va_arg(args, int);
 
@@ -684,17 +686,17 @@ int TownsAudioInterfaceIntern::intf_setTimerB(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_enableTimerA(va_list &args) {
+int TownsAudioInterfaceInternal::intf_enableTimerA(va_list &args) {
 	bufferedWriteReg(0, 0x27, _fmSaveReg[0][0x27] | 0x15);
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_enableTimerB(va_list &args) {
+int TownsAudioInterfaceInternal::intf_enableTimerB(va_list &args) {
 	bufferedWriteReg(0, 0x27, _fmSaveReg[0][0x27] | 0x2a);
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_loadSamples(va_list &args) {
+int TownsAudioInterfaceInternal::intf_loadSamples(va_list &args) {
 	uint32 dest = va_arg(args, uint32);
 	int size = va_arg(args, int);
 	uint8 *src = va_arg(args, uint8*);
@@ -717,7 +719,7 @@ int TownsAudioInterfaceIntern::intf_loadSamples(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_reserveEffectChannels(va_list &args) {
+int TownsAudioInterfaceInternal::intf_reserveEffectChannels(va_list &args) {
 	int numChan = va_arg(args, int);
 	if (numChan > 8)
 		return 3;
@@ -749,7 +751,7 @@ int TownsAudioInterfaceIntern::intf_reserveEffectChannels(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_loadWaveTable(va_list &args) {
+int TownsAudioInterfaceInternal::intf_loadWaveTable(va_list &args) {
 	uint8 *data = va_arg(args, uint8 *);
 	if (_numWaveTables > 127)
 		return 3;
@@ -776,7 +778,7 @@ int TownsAudioInterfaceIntern::intf_loadWaveTable(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_unloadWaveTable(va_list &args) {
+int TownsAudioInterfaceInternal::intf_unloadWaveTable(va_list &args) {
 	int id = va_arg(args, int);
 
 	if (id == -1) {
@@ -803,7 +805,7 @@ int TownsAudioInterfaceIntern::intf_unloadWaveTable(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_pcmPlayEffect(va_list &args) {
+int TownsAudioInterfaceInternal::intf_pcmPlayEffect(va_list &args) {
 	int chan = va_arg(args, int);
 	int note = va_arg(args, int);
 	int velo = va_arg(args, int);
@@ -853,13 +855,13 @@ int TownsAudioInterfaceIntern::intf_pcmPlayEffect(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_pcmChanOff(va_list &args) {
+int TownsAudioInterfaceInternal::intf_pcmChanOff(va_list &args) {
 	int chan = va_arg(args, int);
 	pcmChanOff(chan);
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_pcmEffectPlaying(va_list &args) {
+int TownsAudioInterfaceInternal::intf_pcmEffectPlaying(va_list &args) {
 	int chan = va_arg(args, int);
 	if (chan < 0x40 || chan > 0x47)
 		return 1;
@@ -867,54 +869,54 @@ int TownsAudioInterfaceIntern::intf_pcmEffectPlaying(va_list &args) {
 	return (_pcmChanEffectPlaying & _chanFlags[chan]) ? 1 : 0;
 }
 
-int TownsAudioInterfaceIntern::intf_fmKeyOn(va_list &args) {
+int TownsAudioInterfaceInternal::intf_fmKeyOn(va_list &args) {
 	int chan = va_arg(args, int);
 	int note = va_arg(args, int);
 	int velo = va_arg(args, int);
 	return fmKeyOn(chan, note, velo);
 }
 
-int TownsAudioInterfaceIntern::intf_fmKeyOff(va_list &args) {
+int TownsAudioInterfaceInternal::intf_fmKeyOff(va_list &args) {
 	int chan = va_arg(args, int);
 	return fmKeyOff(chan);
 }
 
-int TownsAudioInterfaceIntern::intf_fmSetPanPos(va_list &args) {
+int TownsAudioInterfaceInternal::intf_fmSetPanPos(va_list &args) {
 	int chan = va_arg(args, int);
 	int mode = va_arg(args, int);
 	return fmSetPanPos(chan, mode);
 }
 
-int TownsAudioInterfaceIntern::intf_fmSetInstrument(va_list &args) {
+int TownsAudioInterfaceInternal::intf_fmSetInstrument(va_list &args) {
 	int chan = va_arg(args, int);
 	int instrId = va_arg(args, int);
 	return fmSetInstrument(chan, instrId);
 }
 
-int TownsAudioInterfaceIntern::intf_fmLoadInstrument(va_list &args) {
+int TownsAudioInterfaceInternal::intf_fmLoadInstrument(va_list &args) {
 	int instrId = va_arg(args, int);
 	uint8 *instrData = va_arg(args, uint8 *);
 	return fmLoadInstrument(instrId, instrData);
 }
 
-int TownsAudioInterfaceIntern::intf_fmSetPitch(va_list &args) {
+int TownsAudioInterfaceInternal::intf_fmSetPitch(va_list &args) {
 	int chan = va_arg(args, int);
 	uint16 freq = va_arg(args, int) & 0xffff;
 	return fmSetPitch(chan, freq);
 }
 
-int TownsAudioInterfaceIntern::intf_fmSetLevel(va_list &args) {
+int TownsAudioInterfaceInternal::intf_fmSetLevel(va_list &args) {
 	int chan = va_arg(args, int);
 	int lvl = va_arg(args, int);
 	return fmSetLevel(chan, lvl);
 }
 
-int TownsAudioInterfaceIntern::intf_fmReset(va_list &args) {
+int TownsAudioInterfaceInternal::intf_fmReset(va_list &args) {
 	fmReset();
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_setOutputVolume(va_list &args) {
+int TownsAudioInterfaceInternal::intf_setOutputVolume(va_list &args) {
 	int chanType = va_arg(args, int);
 	int left = va_arg(args, int);
 	int right = va_arg(args, int);
@@ -951,14 +953,14 @@ int TownsAudioInterfaceIntern::intf_setOutputVolume(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_resetOutputVolume(va_list &args) {
+int TownsAudioInterfaceInternal::intf_resetOutputVolume(va_list &args) {
 	memset(_outputLevel, 0, sizeof(_outputLevel));
 	_outputVolumeFlags = 0;
 	updateOutputVolume();
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_getOutputVolume(va_list &args) {
+int TownsAudioInterfaceInternal::intf_getOutputVolume(va_list &args) {
 	int chanType = va_arg(args, int);
 	int *left = va_arg(args, int*);
 	int *right = va_arg(args, int*);
@@ -978,7 +980,7 @@ int TownsAudioInterfaceIntern::intf_getOutputVolume(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_setOutputMute(va_list &args) {
+int TownsAudioInterfaceInternal::intf_setOutputMute(va_list &args) {
 	int flags = va_arg(args, int);
 	_outputVolumeFlags = flags;
 	uint8 mute = flags & 3;
@@ -1007,31 +1009,31 @@ int TownsAudioInterfaceIntern::intf_setOutputMute(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_cdaToggle(va_list &args) {
+int TownsAudioInterfaceInternal::intf_cdaToggle(va_list &args) {
 	//int mode = va_arg(args, int);
 	//_unkMask = mode ? 0x7f : 0x3f;
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_getOutputVolume2(va_list &args) {
+int TownsAudioInterfaceInternal::intf_getOutputVolume2(va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_getOutputMute (va_list &args) {
+int TownsAudioInterfaceInternal::intf_getOutputMute (va_list &args) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_pcmUpdateEnvelopeGenerator(va_list &args) {
+int TownsAudioInterfaceInternal::intf_pcmUpdateEnvelopeGenerator(va_list &args) {
 	for (int i = 0; i < 8; i++)
 		pcmUpdateEnvelopeGenerator(i);
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::intf_notImpl(va_list &args) {
+int TownsAudioInterfaceInternal::intf_notImpl(va_list &args) {
 	return 4;
 }
 
-void TownsAudioInterfaceIntern::fmReset() {
+void TownsAudioInterfaceInternal::fmReset() {
 	TownsPC98_FmSynth::reset();
 
 	_fmChanPlaying = 0;
@@ -1059,7 +1061,7 @@ void TownsAudioInterfaceIntern::fmReset() {
 	}
 }
 
-int TownsAudioInterfaceIntern::fmKeyOn(int chan, int note, int velo) {
+int TownsAudioInterfaceInternal::fmKeyOn(int chan, int note, int velo) {
 	if (chan > 5)
 		return 1;
 	if (note < 12 || note > 107 || (velo & 0x80))
@@ -1139,7 +1141,7 @@ int TownsAudioInterfaceIntern::fmKeyOn(int chan, int note, int velo) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::fmKeyOff(int chan) {
+int TownsAudioInterfaceInternal::fmKeyOff(int chan) {
 	if (chan > 5)
 		return 1;
 	_fmChanPlaying &= ~_chanFlags[chan];
@@ -1149,7 +1151,7 @@ int TownsAudioInterfaceIntern::fmKeyOff(int chan) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::fmChanOff(int chan) {
+int TownsAudioInterfaceInternal::fmChanOff(int chan) {
 	if (chan > 5)
 		return 1;
 	_fmChanPlaying &= ~_chanFlags[chan];
@@ -1167,7 +1169,7 @@ int TownsAudioInterfaceIntern::fmChanOff(int chan) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::fmSetPanPos(int chan, int value) {
+int TownsAudioInterfaceInternal::fmSetPanPos(int chan, int value) {
 	if (chan > 5)
 		return 1;
 
@@ -1186,7 +1188,7 @@ int TownsAudioInterfaceIntern::fmSetPanPos(int chan, int value) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::fmSetInstrument(int chan, int instrId) {
+int TownsAudioInterfaceInternal::fmSetInstrument(int chan, int instrId) {
 	if (chan > 5)
 		return 1;
 	if (instrId > 127)
@@ -1230,7 +1232,7 @@ int TownsAudioInterfaceIntern::fmSetInstrument(int chan, int instrId) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::fmLoadInstrument(int instrId, const uint8 *data) {
+int TownsAudioInterfaceInternal::fmLoadInstrument(int instrId, const uint8 *data) {
 	if (instrId > 127)
 		return 3;
 	assert(data);
@@ -1238,7 +1240,7 @@ int TownsAudioInterfaceIntern::fmLoadInstrument(int instrId, const uint8 *data)
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::fmSetPitch(int chan, int pitch) {
+int TownsAudioInterfaceInternal::fmSetPitch(int chan, int pitch) {
 	if (chan > 5)
 		return 1;
 
@@ -1325,7 +1327,7 @@ int TownsAudioInterfaceIntern::fmSetPitch(int chan, int pitch) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::fmSetLevel(int chan, int lvl) {
+int TownsAudioInterfaceInternal::fmSetLevel(int chan, int lvl) {
 	if (chan > 5)
 		return 1;
 	if (lvl > 127)
@@ -1348,12 +1350,12 @@ int TownsAudioInterfaceIntern::fmSetLevel(int chan, int lvl) {
 	return 0;
 }
 
-void TownsAudioInterfaceIntern::bufferedWriteReg(uint8 part, uint8 regAddress, uint8 value) {
+void TownsAudioInterfaceInternal::bufferedWriteReg(uint8 part, uint8 regAddress, uint8 value) {
 	_fmSaveReg[part][regAddress] = value;
 	writeReg(part, regAddress, value);
 }
 
-void TownsAudioInterfaceIntern::pcmReset() {
+void TownsAudioInterfaceInternal::pcmReset() {
 	_pcmChanOut = 0;
 	_pcmChanReserved = _pcmChanKeyPressed = _pcmChanEffectPlaying = _pcmChanKeyPlaying = 0;
 	_numReservedChannels = 0;
@@ -1381,7 +1383,7 @@ void TownsAudioInterfaceIntern::pcmReset() {
 	}
 }
 
-int TownsAudioInterfaceIntern::pcmKeyOn(int chan, int note, int velo) {
+int TownsAudioInterfaceInternal::pcmKeyOn(int chan, int note, int velo) {
 	if (chan < 0x40 || chan > 0x47)
 		return 1;
 
@@ -1452,7 +1454,7 @@ int TownsAudioInterfaceIntern::pcmKeyOn(int chan, int note, int velo) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::pcmKeyOff(int chan) {
+int TownsAudioInterfaceInternal::pcmKeyOff(int chan) {
 	if (chan < 0x40 || chan > 0x47)
 		return 1;
 
@@ -1462,7 +1464,7 @@ int TownsAudioInterfaceIntern::pcmKeyOff(int chan) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::pcmChanOff(int chan) {
+int TownsAudioInterfaceInternal::pcmChanOff(int chan) {
 	if (chan < 0x40 || chan > 0x47)
 		return 1;
 
@@ -1476,7 +1478,7 @@ int TownsAudioInterfaceIntern::pcmChanOff(int chan) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::pcmSetPanPos(int chan, int mode) {
+int TownsAudioInterfaceInternal::pcmSetPanPos(int chan, int mode) {
 	if (chan > 0x47)
 		return 1;
 	if (mode & 0x80)
@@ -1499,7 +1501,7 @@ int TownsAudioInterfaceIntern::pcmSetPanPos(int chan, int mode) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::pcmSetInstrument(int chan, int instrId) {
+int TownsAudioInterfaceInternal::pcmSetInstrument(int chan, int instrId) {
 	if (chan > 0x47)
 		return 1;
 	if (instrId > 31)
@@ -1509,7 +1511,7 @@ int TownsAudioInterfaceIntern::pcmSetInstrument(int chan, int instrId) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::pcmLoadInstrument(int instrId, const uint8 *data) {
+int TownsAudioInterfaceInternal::pcmLoadInstrument(int instrId, const uint8 *data) {
 	if (instrId > 31)
 		return 3;
 	assert(data);
@@ -1517,7 +1519,7 @@ int TownsAudioInterfaceIntern::pcmLoadInstrument(int instrId, const uint8 *data)
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::pcmSetPitch(int chan, int pitch) {
+int TownsAudioInterfaceInternal::pcmSetPitch(int chan, int pitch) {
 	if (chan > 0x47)
 		return 1;
 
@@ -1547,7 +1549,7 @@ int TownsAudioInterfaceIntern::pcmSetPitch(int chan, int pitch) {
 	return 0;
 }
 
-int TownsAudioInterfaceIntern::pcmSetLevel(int chan, int lvl) {
+int TownsAudioInterfaceInternal::pcmSetLevel(int chan, int lvl) {
 	if (chan > 0x47)
 		return 1;
 
@@ -1576,7 +1578,7 @@ int TownsAudioInterfaceIntern::pcmSetLevel(int chan, int lvl) {
 	return 0;
 }
 
-void TownsAudioInterfaceIntern::pcmUpdateEnvelopeGenerator(int chan) {
+void TownsAudioInterfaceInternal::pcmUpdateEnvelopeGenerator(int chan) {
 	TownsAudio_PcmChannel *p = &_pcmChan[chan];
 	if (!p->envCurrentLevel) {
 		_pcmChanKeyPlaying &= ~_chanFlags[chan];
@@ -1618,7 +1620,7 @@ void TownsAudioInterfaceIntern::pcmUpdateEnvelopeGenerator(int chan) {
 	p->velo = (p->envCurrentLevel >> 8) << 1;
 }
 
-void TownsAudioInterfaceIntern::pcmCalcPhaseStep(TownsAudio_PcmChannel *p, TownsAudio_WaveTable *w) {
+void TownsAudioInterfaceInternal::pcmCalcPhaseStep(TownsAudio_PcmChannel *p, TownsAudio_WaveTable *w) {
 	int8 diff = p->note - w->baseNote;
 	uint16 r = w->rate + w->rateOffs;
 	uint16 bl = 0;
@@ -1647,7 +1649,16 @@ void TownsAudioInterfaceIntern::pcmCalcPhaseStep(TownsAudio_PcmChannel *p, Towns
 	p->step = (s * p->stepPitch) >> 14;
 }
 
-void TownsAudioInterfaceIntern::updateOutputVolume() {
+void TownsAudioInterfaceInternal::updateOutputVolume() {
+	// Avoid calls to g_system->getAudioCDManager() functions from the main thread
+	// since this can cause mutex lockups.
+	_updateOutputVol = true;
+}
+
+void TownsAudioInterfaceInternal::updateOutputVolumeInternal() {
+	if (!_ready)
+		return;
+
 	// FM Towns seems to support volumes of 0 - 63 for each channel.
 	// We recalculate sane values for our 0 to 255 volume range and
 	// balance values for our -128 to 127 volume range
@@ -1658,38 +1669,41 @@ void TownsAudioInterfaceIntern::updateOutputVolume() {
 	int volume = (int)(((float)(maxVol * 255) / 63.0f));
 	int balance = maxVol ? (int)( ( ((int)_outputLevel[13] * (_outputMute[13] ^ 1) - _outputLevel[12] * (_outputMute[12] ^ 1)) * 127) / (float)maxVol) : 0;
 
+	Common::StackLock lock(_mutex);
 	g_system->getAudioCDManager()->setVolume(volume);
 	g_system->getAudioCDManager()->setBalance(balance);
+
+	_updateOutputVol = false;
 }
 
-TownsAudioInterfaceIntern *TownsAudioInterfaceIntern::_refInstance = 0;
+TownsAudioInterfaceInternal *TownsAudioInterfaceInternal::_refInstance = 0;
 
-int TownsAudioInterfaceIntern::_refCount = 0;
+int TownsAudioInterfaceInternal::_refCount = 0;
 
-const uint8 TownsAudioInterfaceIntern::_chanFlags[] = {
+const uint8 TownsAudioInterfaceInternal::_chanFlags[] = {
 	0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80
 };
 
-const uint16 TownsAudioInterfaceIntern::_frequency[] = {
+const uint16 TownsAudioInterfaceInternal::_frequency[] = {
 	0x028C, 0x02B4, 0x02DC, 0x030A, 0x0338, 0x0368, 0x039C, 0x03D4, 0x040E, 0x044A, 0x048C, 0x04D0
 };
 
-const uint8 TownsAudioInterfaceIntern::_carrier[] = {
+const uint8 TownsAudioInterfaceInternal::_carrier[] = {
 	0x10, 0x10, 0x10, 0x10, 0x30, 0x70, 0x70, 0xF0
 };
 
-const uint8 TownsAudioInterfaceIntern::_fmDefaultInstrument[] = {
+const uint8 TownsAudioInterfaceInternal::_fmDefaultInstrument[] = {
 	0x45, 0x4C, 0x45, 0x50, 0x49, 0x41, 0x4E, 0x4F, 0x01, 0x0A, 0x02, 0x01,
 	0x1E, 0x32, 0x05, 0x00, 0x9C, 0xDC, 0x9C, 0xDC, 0x07, 0x03, 0x14, 0x08,
 	0x00, 0x03, 0x05, 0x05, 0x55, 0x45, 0x27, 0xA7, 0x04, 0xC0, 0x00, 0x00,
 	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
 };
 
-const uint16 TownsAudioInterfaceIntern::_pcmPhase1[] =  {
+const uint16 TownsAudioInterfaceInternal::_pcmPhase1[] =  {
 	0x879B, 0x0F37, 0x1F58, 0x306E, 0x4288, 0x55B6, 0x6A08, 0x7F8F, 0x965E, 0xAE88, 0xC882, 0xE341
 };
 
-const uint16 TownsAudioInterfaceIntern::_pcmPhase2[] =  {
+const uint16 TownsAudioInterfaceInternal::_pcmPhase2[] =  {
 	0xFEFE, 0xF1A0, 0xE411, 0xD744, 0xCB2F, 0xBFC7, 0xB504, 0xAAE2, 0xA144, 0x9827, 0x8FAC
 };
 
@@ -1841,11 +1855,11 @@ void TownsAudio_WaveTable::clear() {
 }
 
 TownsAudioInterface::TownsAudioInterface(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver) {
-	_intf = TownsAudioInterfaceIntern::addNewRef(mixer, driver);
+	_intf = TownsAudioInterfaceInternal::addNewRef(mixer, driver);
 }
 
 TownsAudioInterface::~TownsAudioInterface() {
-	TownsAudioInterfaceIntern::releaseRef();
+	TownsAudioInterfaceInternal::releaseRef();
 	_intf = 0;
 }
 
@@ -1874,3 +1888,11 @@ void TownsAudioInterface::setSoundEffectVolume(int volume) {
 void TownsAudioInterface::setSoundEffectChanMask(int mask) {
 	_intf->setSoundEffectChanMask(mask);
 }
+
+void TownsAudioInterface::lockInternal() {
+	_intf->lock();
+}
+
+void TownsAudioInterface::unlockInternal() {
+	_intf->unlock();
+}
diff --git a/audio/softsynth/fmtowns_pc98/towns_audio.h b/audio/softsynth/fmtowns_pc98/towns_audio.h
index 2c58d46d06..b00243f610 100644
--- a/audio/softsynth/fmtowns_pc98/towns_audio.h
+++ b/audio/softsynth/fmtowns_pc98/towns_audio.h
@@ -25,7 +25,7 @@
 
 #include "audio/mixer.h"
 
-class TownsAudioInterfaceIntern;
+class TownsAudioInterfaceInternal;
 
 class TownsAudioInterfacePluginDriver {
 public:
@@ -48,8 +48,15 @@ public:
 	// The first 6 bits are the 6 fm channels. The next 8 bits are pcm channels.
 	void setSoundEffectChanMask(int mask);
 
+	// These methods should not be needed in standard situations, since the mutex
+	// is handled internally. However, they may be required to avoid lockup situations
+	// if the code using this class has a mutex of its own (example for a lockup
+	// situation: imuse.cpp, line 78).
+	void lockInternal();
+	void unlockInternal();
+
 private:
-	TownsAudioInterfaceIntern *_intf;
+	TownsAudioInterfaceInternal *_intf;
 };
 
 #endif
diff --git a/audio/softsynth/fmtowns_pc98/towns_midi.cpp b/audio/softsynth/fmtowns_pc98/towns_midi.cpp
index 3c7ce7d0e4..00f0d43b98 100644
--- a/audio/softsynth/fmtowns_pc98/towns_midi.cpp
+++ b/audio/softsynth/fmtowns_pc98/towns_midi.cpp
@@ -835,19 +835,6 @@ const uint8 TownsMidiInputChannel::_programAdjustLevel[] = {
 MidiDriver_TOWNS::MidiDriver_TOWNS(Audio::Mixer *mixer) : _timerProc(0), _timerProcPara(0), _channels(0), _out(0),
 	_chanState(0), _operatorLevelTable(0), _tickCounter1(0), _tickCounter2(0), _rand(1), _allocCurPos(0), _isOpen(false) {
 	_intf = new TownsAudioInterface(mixer, this);
-}
-
-MidiDriver_TOWNS::~MidiDriver_TOWNS() {
-	close();
-	delete _intf;
-}
-
-int MidiDriver_TOWNS::open() {
-	if (_isOpen)
-		return MERR_ALREADY_OPEN;
-
-	if (!_intf->init())
-		return MERR_CANNOT_CONNECT;
 
 	_channels = new TownsMidiInputChannel*[32];
 	for (int i = 0; i < 32; i++)
@@ -866,6 +853,38 @@ int MidiDriver_TOWNS::open() {
 	}
 	for (int i = 0; i < 64; i++)
 		_operatorLevelTable[i << 5] = 0;
+}
+
+MidiDriver_TOWNS::~MidiDriver_TOWNS() {
+	close();
+	delete _intf;
+
+	if (_channels) {
+		for (int i = 0; i < 32; i++)
+			delete _channels[i];
+		delete[] _channels;
+	}
+	_channels = 0;
+
+	if (_out) {
+		for (int i = 0; i < 6; i++)
+			delete _out[i];
+		delete[] _out;
+	}
+	_out = 0;
+
+	delete[] _chanState;
+	_chanState = 0;
+	delete[] _operatorLevelTable;
+	_operatorLevelTable = 0;
+}
+
+int MidiDriver_TOWNS::open() {
+	if (_isOpen)
+		return MERR_ALREADY_OPEN;
+
+	if (!_intf->init())
+		return MERR_CANNOT_CONNECT;
 
 	_intf->callback(0);
 
@@ -876,9 +895,7 @@ int MidiDriver_TOWNS::open() {
 	_intf->callback(33, 8);
 	_intf->setSoundEffectChanMask(~0x3f);
 
-	 _tickCounter1 = _tickCounter2 = 0;
-	 _allocCurPos = 0;
-	 _rand = 1;
+	_allocCurPos = 0;
 
 	_isOpen = true;
 
@@ -893,25 +910,6 @@ void MidiDriver_TOWNS::close() {
 
 	setTimerCallback(0, 0);
 	g_system->delayMillis(20);
-	
-	if (_channels) {
-		for (int i = 0; i < 32; i++)
-			delete _channels[i];
-		delete[] _channels;
-	}
-	_channels = 0;
-
-	if (_out) {
-		for (int i = 0; i < 6; i++)
-			delete _out[i];
-		delete[] _out;
-	}
-	_out = 0;
-
-	delete[] _chanState;
-	_chanState = 0;
-	delete[] _operatorLevelTable;
-	_operatorLevelTable = 0;
 }
 
 void MidiDriver_TOWNS::send(uint32 b) {
diff --git a/audio/softsynth/fmtowns_pc98/towns_pc98_driver.cpp b/audio/softsynth/fmtowns_pc98/towns_pc98_driver.cpp
index e35da91cbb..ee20068e74 100644
--- a/audio/softsynth/fmtowns_pc98/towns_pc98_driver.cpp
+++ b/audio/softsynth/fmtowns_pc98/towns_pc98_driver.cpp
@@ -1145,7 +1145,7 @@ void TownsPC98_AudioDriver::loadMusicData(uint8 *data, bool loadPaused) {
 
 	reset();
 
-	lock();
+	Common::StackLock lock(_mutex);
 	uint8 *src_a = _trackPtr = _musicBuffer = data;
 
 	for (uint8 i = 0; i < 3; i++) {
@@ -1176,7 +1176,6 @@ void TownsPC98_AudioDriver::loadMusicData(uint8 *data, bool loadPaused) {
 	_finishedChannelsFlag = _finishedSSGFlag = _finishedRhythmFlag = 0;
 
 	_musicPlaying = (loadPaused ? false : true);
-	unlock();
 }
 
 void TownsPC98_AudioDriver::loadSoundEffectData(uint8 *data, uint8 trackNum) {
@@ -1195,17 +1194,16 @@ void TownsPC98_AudioDriver::loadSoundEffectData(uint8 *data, uint8 trackNum) {
 		return;
 	}
 
-	lock();
+	Common::StackLock lock(_mutex);
 	_sfxData = _sfxBuffer = data;
 	_sfxOffsets[0] = READ_LE_UINT16(&_sfxData[(trackNum << 2)]);
 	_sfxOffsets[1] = READ_LE_UINT16(&_sfxData[(trackNum << 2) + 2]);
 	_sfxPlaying = true;
 	_finishedSfxFlag = 0;
-	unlock();
 }
 
 void TownsPC98_AudioDriver::reset() {
-	lock();
+	Common::StackLock lock(_mutex);
 
 	_musicPlaying = false;
 	_sfxPlaying = false;
@@ -1232,7 +1230,6 @@ void TownsPC98_AudioDriver::reset() {
 	if (_rhythmChannel)
 		_rhythmChannel->reset();
 #endif
-	unlock();
 }
 
 void TownsPC98_AudioDriver::fadeStep() {
@@ -1263,37 +1260,30 @@ void TownsPC98_AudioDriver::fadeStep() {
 	}
 }
 
-void TownsPC98_AudioDriver::timerCallbackB() {
-	_sfxOffs = 0;
-
-	if (_musicPlaying) {
-		_musicTickCounter++;
-
-		for (int i = 0; i < _numChan; i++) {
-			if (_updateChannelsFlag & _channels[i]->_idFlag) {
-				_channels[i]->processEvents();
-				_channels[i]->processFrequency();
-			}
-		}
+void TownsPC98_AudioDriver::pause() {
+	_musicPlaying = false;
+}
+	
+void TownsPC98_AudioDriver::cont() {
+	_musicPlaying = true;
+}
 
-		for (int i = 0; i < _numSSG; i++) {
-			if (_updateSSGFlag & _ssgChannels[i]->_idFlag) {
-				_ssgChannels[i]->processEvents();
-				_ssgChannels[i]->processFrequency();
-			}
-		}
+bool TownsPC98_AudioDriver::looping() {
+	return _looping == _updateChannelsFlag ? true : false;
+}
 
-#ifndef DISABLE_PC98_RHYTHM_CHANNEL
-		if (_hasPercussion)
-			if (_updateRhythmFlag & _rhythmChannel->_idFlag)
-				_rhythmChannel->processEvents();
-#endif
-	}
+bool TownsPC98_AudioDriver::musicPlaying() {
+	return _musicPlaying;
+}
 
-	toggleRegProtection(false);
+void TownsPC98_AudioDriver::setMusicVolume(int volume) {
+	_musicVolume = volume;
+	setVolumeIntern(_musicVolume, _sfxVolume);
+}
 
-	if (_finishedChannelsFlag == _updateChannelsFlag && _finishedSSGFlag == _updateSSGFlag && _finishedRhythmFlag == _updateRhythmFlag)
-		_musicPlaying = false;
+void TownsPC98_AudioDriver::setSoundEffectVolume(int volume) {
+	_sfxVolume = volume;
+	setVolumeIntern(_musicVolume, _sfxVolume);
 }
 
 void TownsPC98_AudioDriver::timerCallbackA() {
@@ -1321,15 +1311,37 @@ void TownsPC98_AudioDriver::timerCallbackA() {
 	}
 }
 
-void TownsPC98_AudioDriver::setMusicTempo(uint8 tempo) {
-	writeReg(0, 0x26, tempo);
-	writeReg(0, 0x27, 0x33);
-}
+void TownsPC98_AudioDriver::timerCallbackB() {
+	_sfxOffs = 0;
 
-void TownsPC98_AudioDriver::setSfxTempo(uint16 tempo) {
-	writeReg(0, 0x24, tempo & 0xff);
-	writeReg(0, 0x25, tempo >> 8);
-	writeReg(0, 0x27, 0x33);
+	if (_musicPlaying) {
+		_musicTickCounter++;
+
+		for (int i = 0; i < _numChan; i++) {
+			if (_updateChannelsFlag & _channels[i]->_idFlag) {
+				_channels[i]->processEvents();
+				_channels[i]->processFrequency();
+			}
+		}
+
+		for (int i = 0; i < _numSSG; i++) {
+			if (_updateSSGFlag & _ssgChannels[i]->_idFlag) {
+				_ssgChannels[i]->processEvents();
+				_ssgChannels[i]->processFrequency();
+			}
+		}
+
+#ifndef DISABLE_PC98_RHYTHM_CHANNEL
+		if (_hasPercussion)
+			if (_updateRhythmFlag & _rhythmChannel->_idFlag)
+				_rhythmChannel->processEvents();
+#endif
+	}
+
+	toggleRegProtection(false);
+
+	if (_finishedChannelsFlag == _updateChannelsFlag && _finishedSSGFlag == _updateSSGFlag && _finishedRhythmFlag == _updateRhythmFlag)
+		_musicPlaying = false;
 }
 
 void TownsPC98_AudioDriver::startSoundEffect() {
@@ -1352,6 +1364,16 @@ void TownsPC98_AudioDriver::startSoundEffect() {
 	_sfxData = 0;
 }
 
+void TownsPC98_AudioDriver::setMusicTempo(uint8 tempo) {
+	writeReg(0, 0x26, tempo);
+	writeReg(0, 0x27, 0x33);
+}
+
+void TownsPC98_AudioDriver::setSfxTempo(uint16 tempo) {
+	writeReg(0, 0x24, tempo & 0xff);
+	writeReg(0, 0x25, tempo >> 8);
+	writeReg(0, 0x27, 0x33);
+}
 const uint8 TownsPC98_AudioDriver::_drvTables[] = {
 	//  channel presets
 	0x00, 0x80, 0x00, 0x00, 0x00, 0x01,
diff --git a/audio/softsynth/fmtowns_pc98/towns_pc98_driver.h b/audio/softsynth/fmtowns_pc98/towns_pc98_driver.h
index 46ee23895b..ff58482227 100644
--- a/audio/softsynth/fmtowns_pc98/towns_pc98_driver.h
+++ b/audio/softsynth/fmtowns_pc98/towns_pc98_driver.h
@@ -50,33 +50,19 @@ public:
 
 	void fadeStep();
 
-	void pause() {
-		_musicPlaying = false;
-	}
-	void cont() {
-		_musicPlaying = true;
-	}
+	void pause();
+	void cont();
 
-	void timerCallbackB();
+	bool looping();
+	bool musicPlaying();
+
+	void setMusicVolume(int volume);
+	void setSoundEffectVolume(int volume);
+
+private:
 	void timerCallbackA();
+	void timerCallbackB();
 
-	bool looping() {
-		return _looping == _updateChannelsFlag ? true : false;
-	}
-	bool musicPlaying() {
-		return _musicPlaying;
-	}
-
-	void setMusicVolume(int volume) {
-		_musicVolume = volume;
-		setVolumeIntern(_musicVolume, _sfxVolume);
-	}
-	void setSoundEffectVolume(int volume) {
-		_sfxVolume = volume;
-		setVolumeIntern(_musicVolume, _sfxVolume);
-	}
-
-protected:
 	void startSoundEffect();
 
 	void setMusicTempo(uint8 tempo);
diff --git a/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.cpp b/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.cpp
index bc5aa32823..b09a9f65d1 100644
--- a/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.cpp
+++ b/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.cpp
@@ -861,7 +861,7 @@ TownsPC98_FmSynth::TownsPC98_FmSynth(Audio::Mixer *mixer, EmuType type) :
 	_hasPercussion(type == kType86 ? true : false),
 	_oprRates(0), _oprRateshift(0), _oprAttackDecay(0), _oprFrq(0), _oprSinTbl(0), _oprLevelOut(0), _oprDetune(0),
 	 _rtt(type == kTypeTowns ? 0x514767 : 0x5B8D80), _baserate(55125.0f / (float)mixer->getOutputRate()),
-	_volMaskA(0), _volMaskB(0), _volumeA(255), _volumeB(255), _regProtectionFlag(false), _lock(0), _ready(false) {
+	_volMaskA(0), _volMaskB(0), _volumeA(255), _volumeB(255), _regProtectionFlag(false), _ready(false) {
 
 	memset(&_timers[0], 0, sizeof(ChipTimer));
 	memset(&_timers[1], 0, sizeof(ChipTimer));
@@ -928,7 +928,7 @@ bool TownsPC98_FmSynth::init() {
 }
 
 void TownsPC98_FmSynth::reset() {
-	lock();
+	Common::StackLock lock(_mutex);
 	for (int i = 0; i < _numChan; i++) {
 		for (int ii = 0; ii < 4; ii++)
 			_chanInternal[i].opr[ii]->reset();
@@ -948,14 +948,13 @@ void TownsPC98_FmSynth::reset() {
 	if (_prc)
 		_prc->reset();
 #endif
-	unlock();
 }
 
 void TownsPC98_FmSynth::writeReg(uint8 part, uint8 regAddress, uint8 value) {
 	if (_regProtectionFlag || !_ready)
 		return;
 
-	lock();
+	Common::StackLock lock(_mutex);
 
 	static const uint8 oprOrdr[] = { 0, 2, 1, 3 };
 
@@ -1137,7 +1136,6 @@ void TownsPC98_FmSynth::writeReg(uint8 part, uint8 regAddress, uint8 value) {
 	default:
 		warning("TownsPC98_FmSynth: UNKNOWN ADDRESS %d", regAddress);
 	}
-	unlock();
 }
 
 int TownsPC98_FmSynth::readBuffer(int16 *buffer, const int numSamples) {
@@ -1146,9 +1144,14 @@ int TownsPC98_FmSynth::readBuffer(int16 *buffer, const int numSamples) {
 	int32 *tmpStart = tmp;
 	memset(tmp, 0, sizeof(int32) * numSamples);
 	int32 samplesLeft = numSamples >> 1;
-	_lock |= 0x10000;
 
-	while (_ready && !(_lock & 0xffff) && samplesLeft) {
+	bool locked = false;
+	if (_ready) {
+		lock();
+		locked = true;
+	}
+
+	while (_ready && samplesLeft) {
 		int32 render = samplesLeft;
 
 		for (int i = 0; i < 2; i++) {
@@ -1197,17 +1200,38 @@ int TownsPC98_FmSynth::readBuffer(int16 *buffer, const int numSamples) {
 		tmp += (render << 1);
 	}
 
-	_lock &= ~0x10000;
+	if (locked)
+		unlock();
+
 	delete[] tmpStart;
 
 	return numSamples;
 }
 
+bool TownsPC98_FmSynth::isStereo() const {
+	return true;
+}
+
+bool TownsPC98_FmSynth::endOfData() const {
+	return false;
+}
+
+int TownsPC98_FmSynth::getRate() const {
+	return _mixer->getOutputRate();
+}
+
+void TownsPC98_FmSynth::lock() {
+	_mutex.lock();
+}
+
+void TownsPC98_FmSynth::unlock() {
+	_mutex.unlock();
+}
+
 void TownsPC98_FmSynth::deinit() {
 	_ready = false;
-	while (_lock)
-		g_system->delayMillis(20);
 	_mixer->stopHandle(_soundHandle);
+	Common::StackLock lock(_mutex);
 	_timers[0].cb = _timers[1].cb = &TownsPC98_FmSynth::idleTimerCallback;
 }
 
@@ -1216,7 +1240,7 @@ uint8 TownsPC98_FmSynth::readSSGStatus() {
 }
 
 void TownsPC98_FmSynth::setVolumeIntern(int volA, int volB) {
-	lock();
+	Common::StackLock lock(_mutex);
 	_volumeA = CLIP<uint16>(volA, 0, Audio::Mixer::kMaxMixerVolume);
 	_volumeB = CLIP<uint16>(volB, 0, Audio::Mixer::kMaxMixerVolume);
 	if (_ssg)
@@ -1225,11 +1249,10 @@ void TownsPC98_FmSynth::setVolumeIntern(int volA, int volB) {
 	if (_prc)
 		_prc->setVolumeIntern(_volumeA, _volumeB);
 #endif
-	unlock();
 }
 
 void TownsPC98_FmSynth::setVolumeChannelMasks(int channelMaskA, int channelMaskB) {
-	lock();
+	Common::StackLock lock(_mutex);
 	_volMaskA = channelMaskA;
 	_volMaskB = channelMaskB;
 	if (_ssg)
@@ -1238,17 +1261,6 @@ void TownsPC98_FmSynth::setVolumeChannelMasks(int channelMaskA, int channelMaskB
 	if (_prc)
 		_prc->setVolumeChannelMasks(_volMaskA >> (_numChan + _numSSG), _volMaskB >> (_numChan + _numSSG));
 #endif
-	unlock();
-}
-
-void TownsPC98_FmSynth::lock() {
-	_mutex.lock();
-	_lock++;
-}
-
-void  TownsPC98_FmSynth::unlock() {
-	_mutex.unlock();
-	_lock--;
 }
 
 void TownsPC98_FmSynth::generateTables() {
diff --git a/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.h b/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.h
index f7bcc90585..a1b09abd3a 100644
--- a/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.h
+++ b/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.h
@@ -69,15 +69,12 @@ public:
 
 	// AudioStream interface
 	int readBuffer(int16 *buffer, const int numSamples);
-	bool isStereo() const {
-		return true;
-	}
-	bool endOfData() const {
-		return false;
-	}
-	int getRate() const {
-		return _mixer->getOutputRate();
-	}
+	bool isStereo() const;
+	bool endOfData() const;
+	int getRate() const;
+
+	void lock();
+	void unlock();
 
 protected:
 	void deinit();
@@ -102,13 +99,12 @@ protected:
 	void setVolumeIntern(int volA, int volB);
 	void setVolumeChannelMasks(int channelMaskA, int channelMaskB);
 
-	void lock();
-	void unlock();
-
 	const int _numChan;
 	const int _numSSG;
 	const bool _hasPercussion;
 
+	Common::Mutex _mutex;
+
 private:
 	void generateTables();
 	void nextTick(int32 *buffer, uint32 bufferSize);
@@ -182,9 +178,6 @@ private:
 	Audio::Mixer *_mixer;
 	Audio::SoundHandle _soundHandle;
 
-	int _lock;
-	Common::Mutex _mutex;
-
 #ifndef DISABLE_PC98_RHYTHM_CHANNEL
 	static const uint8 _percussionData[];
 #endif