AUDIO: (FM-Towns/PC98) - cleanup mutex handling

6 files changed, 77 insertions, 83 deletions

diff --git a/audio/softsynth/fmtowns_pc98/pc98_audio.cpp b/audio/softsynth/fmtowns_pc98/pc98_audio.cpp
index 3ad100911a..c8d58f6923 100644
--- a/audio/softsynth/fmtowns_pc98/pc98_audio.cpp
+++ b/audio/softsynth/fmtowns_pc98/pc98_audio.cpp
@@ -26,11 +26,11 @@
 
 class PC98AudioCoreInternal : public TownsPC98_FmSynth {
 private:
-	PC98AudioCoreInternal(Audio::Mixer *mixer, PC98AudioCore *owner, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type, bool externalMutexHandling = false);
+	PC98AudioCoreInternal(Audio::Mixer *mixer, PC98AudioCore *owner, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type);
 public:
 	~PC98AudioCoreInternal();
 
-	static PC98AudioCoreInternal *addNewRef(Audio::Mixer *mixer, PC98AudioCore *owner, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type, bool externalMutexHandling = false);
+	static PC98AudioCoreInternal *addNewRef(Audio::Mixer *mixer, PC98AudioCore *owner, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type);
 	static void releaseRef(PC98AudioCore *owner);
 
 	bool init();
@@ -69,8 +69,8 @@ private:
 	static int _refCount;
 };
 
-PC98AudioCoreInternal::PC98AudioCoreInternal(Audio::Mixer *mixer, PC98AudioCore *owner, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type, bool externalMutexHandling) :
-	TownsPC98_FmSynth(mixer, (TownsPC98_FmSynth::EmuType)type, externalMutexHandling),
+PC98AudioCoreInternal::PC98AudioCoreInternal(Audio::Mixer *mixer, PC98AudioCore *owner, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type) :
+	TownsPC98_FmSynth(mixer, (TownsPC98_FmSynth::EmuType)type),
 	_drv(driver), _drvOwner(owner),
 	_musicVolume(Audio::Mixer::kMaxMixerVolume), _sfxVolume(Audio::Mixer::kMaxMixerVolume),
 	_port1(type == PC98AudioPluginDriver::kTypeTowns ? 0x4D8 : 0x188), _port2(type == PC98AudioPluginDriver::kTypeTowns ? 0x4DA : 0x18A),
@@ -80,22 +80,22 @@ PC98AudioCoreInternal::PC98AudioCoreInternal(Audio::Mixer *mixer, PC98AudioCore
 }
 
 PC98AudioCoreInternal::~PC98AudioCoreInternal() {
+	Common::StackLock lock(_mutex);
 	_ready = false;
 	deinit();
 
-	Common::StackLock lock(_mutex);
 	/*
 	
 	*/
 }
 
-PC98AudioCoreInternal *PC98AudioCoreInternal::addNewRef(Audio::Mixer *mixer, PC98AudioCore *owner, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type, bool externalMutexHandling) {
+PC98AudioCoreInternal *PC98AudioCoreInternal::addNewRef(Audio::Mixer *mixer, PC98AudioCore *owner, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type) {
 	_refCount++;
 	if (_refCount == 1 && _refInstance == 0)
-		_refInstance = new PC98AudioCoreInternal(mixer, owner, driver, type, externalMutexHandling);
+		_refInstance = new PC98AudioCoreInternal(mixer, owner, driver, type);
 	else if (_refCount < 2 || _refInstance == 0)
 		error("PC98AudioCoreInternal::addNewRef(): Internal reference management failure");
-	else if (!_refInstance->assignPluginDriver(owner, driver, externalMutexHandling))
+	else if (!_refInstance->assignPluginDriver(owner, driver))
 		error("PC98AudioCoreInternal::addNewRef(): Plugin driver conflict");
 
 	return _refInstance;
@@ -139,6 +139,7 @@ bool PC98AudioCoreInternal::init() {
 }
 
 void PC98AudioCoreInternal::writePort(uint16 port, uint8 value) {
+	Common::StackLock lock(_mutex);
 	if (port == _port1)
 		_address[0] = value;
 	else if (port == _port2 && _address[0] < 0xc0) {
@@ -153,6 +154,7 @@ void PC98AudioCoreInternal::writePort(uint16 port, uint8 value) {
 }
 
 uint8 PC98AudioCoreInternal::readPort(uint16 port) {
+	Common::StackLock lock(_mutex);
 	uint8 val = 0;
 	if (port == _port2 && _address[0] < 0xc0) {
 		val = readReg(0, _address[0]);
@@ -165,20 +167,24 @@ uint8 PC98AudioCoreInternal::readPort(uint16 port) {
 }
 
 void PC98AudioCoreInternal::setMusicVolume(int volume) {
+	Common::StackLock lock(_mutex);
 	_musicVolume = CLIP<uint16>(volume, 0, Audio::Mixer::kMaxMixerVolume);
 	setVolumeIntern(_musicVolume, _sfxVolume);
 }
 
 void PC98AudioCoreInternal::setSoundEffectVolume(int volume) {
+	Common::StackLock lock(_mutex);
 	_sfxVolume = CLIP<uint16>(volume, 0, Audio::Mixer::kMaxMixerVolume);
 	setVolumeIntern(_musicVolume, _sfxVolume);
 }
 
 void PC98AudioCoreInternal::setSoundEffectChanMask(int mask) {
+	Common::StackLock lock(_mutex);
 	setVolumeChannelMasks(~mask, mask);
 }
 
 void PC98AudioCoreInternal::ssgSetVolume(int volume) {
+	Common::StackLock lock(_mutex);
 	setLevelSSG(volume);
 }
 
@@ -187,6 +193,7 @@ Common::Mutex &PC98AudioCoreInternal::mutex() {
 }
 
 bool PC98AudioCoreInternal::assignPluginDriver(PC98AudioCore *owner, PC98AudioPluginDriver *driver, bool externalMutexHandling) {
+	Common::StackLock lock(_mutex);
 	if (_refCount <= 1)
 		return true;
 
@@ -194,28 +201,27 @@ bool PC98AudioCoreInternal::assignPluginDriver(PC98AudioCore *owner, PC98AudioPl
 		if (driver && driver != _drv)
 			return false;
 	} else {
-		Common::StackLock lock(_mutex);
 		_drv = driver;
 		_drvOwner = owner;
-		_externalMutex = externalMutexHandling;
 	}
 
 	return true;
 }
 
 void PC98AudioCoreInternal::removePluginDriver(PC98AudioCore *owner) {
-	if (_drvOwner == owner) {
-		Common::StackLock lock(_mutex);
+	Common::StackLock lock(_mutex);
+	if (_drvOwner == owner)
 		_drv = 0;
-	}
 }
 
 void PC98AudioCoreInternal::timerCallbackA() {
+	Common::StackLock lock(_mutex);
 	if (_drv && _ready)
 		_drv->timerCallbackA();
 }
 
 void PC98AudioCoreInternal::timerCallbackB() {
+	Common::StackLock lock(_mutex);
 	if (_drv && _ready)
 		_drv->timerCallbackB();
 }
@@ -224,8 +230,8 @@ PC98AudioCoreInternal *PC98AudioCoreInternal::_refInstance = 0;
 
 int PC98AudioCoreInternal::_refCount = 0;
 
-PC98AudioCore::PC98AudioCore(Audio::Mixer *mixer, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type, bool externalMutexHandling) {
-	_internal = PC98AudioCoreInternal::addNewRef(mixer, this, driver, type, externalMutexHandling);
+PC98AudioCore::PC98AudioCore(Audio::Mixer *mixer, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type) {
+	_internal = PC98AudioCoreInternal::addNewRef(mixer, this, driver, type);
 }
 
 PC98AudioCore::~PC98AudioCore() {
diff --git a/audio/softsynth/fmtowns_pc98/pc98_audio.h b/audio/softsynth/fmtowns_pc98/pc98_audio.h
index b6269f0f67..2bfae78cd4 100644
--- a/audio/softsynth/fmtowns_pc98/pc98_audio.h
+++ b/audio/softsynth/fmtowns_pc98/pc98_audio.h
@@ -45,7 +45,7 @@ public:
 
 class PC98AudioCore {
 public:
-	PC98AudioCore(Audio::Mixer *mixer, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type, bool externalMutexHandling = false);
+	PC98AudioCore(Audio::Mixer *mixer, PC98AudioPluginDriver *driver, PC98AudioPluginDriver::EmuType type);
 	~PC98AudioCore();
 
 	bool init();
diff --git a/audio/softsynth/fmtowns_pc98/towns_audio.cpp b/audio/softsynth/fmtowns_pc98/towns_audio.cpp
index 1a12fa9443..1464dd73b7 100644
--- a/audio/softsynth/fmtowns_pc98/towns_audio.cpp
+++ b/audio/softsynth/fmtowns_pc98/towns_audio.cpp
@@ -135,11 +135,11 @@ private:
 
 class TownsAudioInterfaceInternal : public TownsPC98_FmSynth {
 private:
-	TownsAudioInterfaceInternal(Audio::Mixer *mixer, TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver, bool externalMutexHandling = false);
+	TownsAudioInterfaceInternal(Audio::Mixer *mixer, TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver);
 public:
 	~TownsAudioInterfaceInternal();
 
-	static TownsAudioInterfaceInternal *addNewRef(Audio::Mixer *mixer, TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver, bool externalMutexHandling = false);
+	static TownsAudioInterfaceInternal *addNewRef(Audio::Mixer *mixer, TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver);
 	static void releaseRef(TownsAudioInterface *owner);
 
 	bool init();
@@ -154,7 +154,7 @@ public:
 	void setSoundEffectChanMask(int mask);
 
 private:
-	bool assignPluginDriver(TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver, bool externalMutexHandling = false);
+	bool assignPluginDriver(TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver);
 	void removePluginDriver(TownsAudioInterface *owner);
 
 	void nextTickEx(int32 *buffer, uint32 bufferSize);
@@ -275,8 +275,8 @@ private:
 	static const uint8 _fmDefaultInstrument[];
 };
 
-TownsAudioInterfaceInternal::TownsAudioInterfaceInternal(Audio::Mixer *mixer, TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver, bool externalMutexHandling) :
-	TownsPC98_FmSynth(mixer, kTypeTowns, externalMutexHandling),
+TownsAudioInterfaceInternal::TownsAudioInterfaceInternal(Audio::Mixer *mixer, TownsAudioInterface *owner, 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), _drvOwner(owner),
 	_pcmSfxChanMask(0),	_musicVolume(Audio::Mixer::kMaxMixerVolume), _sfxVolume(Audio::Mixer::kMaxMixerVolume),
@@ -404,11 +404,10 @@ TownsAudioInterfaceInternal::TownsAudioInterfaceInternal(Audio::Mixer *mixer, To
 }
 
 TownsAudioInterfaceInternal::~TownsAudioInterfaceInternal() {
+	Common::StackLock lock(_mutex);
 	_ready = false;
 	deinit();
 
-	Common::StackLock lock(_mutex);
-
 	delete[] _fmSaveReg[0];
 	delete[] _fmSaveReg[1];
 	delete[] _fmInstruments;
@@ -417,13 +416,13 @@ TownsAudioInterfaceInternal::~TownsAudioInterfaceInternal() {
 	delete[] _pcmChan;
 }
 
-TownsAudioInterfaceInternal *TownsAudioInterfaceInternal::addNewRef(Audio::Mixer *mixer, TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver, bool externalMutexHandling) {
+TownsAudioInterfaceInternal *TownsAudioInterfaceInternal::addNewRef(Audio::Mixer *mixer, TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver) {
 	_refCount++;
 	if (_refCount == 1 && _refInstance == 0)
-		_refInstance = new TownsAudioInterfaceInternal(mixer, owner, driver, externalMutexHandling);
+		_refInstance = new TownsAudioInterfaceInternal(mixer, owner, driver);
 	else if (_refCount < 2 || _refInstance == 0)
 		error("TownsAudioInterfaceInternal::addNewRef(): Internal reference management failure");
-	else if (!_refInstance->assignPluginDriver(owner, driver, externalMutexHandling))
+	else if (!_refInstance->assignPluginDriver(owner, driver))
 		error("TownsAudioInterfaceInternal::addNewRef(): Plugin driver conflict");
 
 	return _refInstance;
@@ -448,9 +447,6 @@ bool TownsAudioInterfaceInternal::init() {
 	if (_ready)
 		return true;
 
-	if (!TownsPC98_FmSynth::init())
-		return false;
-
 	_fmSaveReg[0] = new uint8[256];
 	_fmSaveReg[1] = new uint8[256];
 	_fmInstruments = new uint8[128 * 48];
@@ -460,6 +456,10 @@ bool TownsAudioInterfaceInternal::init() {
 
 	_timer = 0;
 
+	if (!TownsPC98_FmSynth::init())
+		return false;
+
+
 	setVolumeChannelMasks(-1, 0);
 
 	_ready = true;
@@ -469,6 +469,7 @@ bool TownsAudioInterfaceInternal::init() {
 }
 
 int TownsAudioInterfaceInternal::callback(int command, ...) {
+	Common::StackLock lock(_mutex);
 	if (!_ready)
 		return 1;
 
@@ -482,35 +483,39 @@ int TownsAudioInterfaceInternal::callback(int command, ...) {
 }
 
 int TownsAudioInterfaceInternal::processCommand(int command, va_list &args) {
+	Common::StackLock lock(_mutex);
 	if (!_ready)
 		return 1;
 
 	if (command < 0 || command > 81)
 		return 4;
-
-	Common::StackLock lock(_mutex);
+	
 	int res = (this->*_intfOpcodes[command])(args);
 
 	return res;
 }
 
 void TownsAudioInterfaceInternal::setMusicVolume(int volume) {
+	Common::StackLock lock(_mutex);
 	_musicVolume = CLIP<uint16>(volume, 0, Audio::Mixer::kMaxMixerVolume);
 	setVolumeIntern(_musicVolume, _sfxVolume);
 }
 
 void TownsAudioInterfaceInternal::setSoundEffectVolume(int volume) {
+	Common::StackLock lock(_mutex);
 	_sfxVolume = CLIP<uint16>(volume, 0, Audio::Mixer::kMaxMixerVolume);
 	setVolumeIntern(_musicVolume, _sfxVolume);
 }
 
 void TownsAudioInterfaceInternal::setSoundEffectChanMask(int mask) {
+	Common::StackLock lock(_mutex);
 	_pcmSfxChanMask = mask >> 6;
 	mask &= 0x3f;
 	setVolumeChannelMasks(~mask, mask);
 }
 
-bool TownsAudioInterfaceInternal::assignPluginDriver(TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver, bool externalMutexHandling) {
+bool TownsAudioInterfaceInternal::assignPluginDriver(TownsAudioInterface *owner, TownsAudioInterfacePluginDriver *driver) {
+	Common::StackLock lock(_mutex);
 	if (_refCount <= 1)
 		return true;
 
@@ -518,23 +523,21 @@ bool TownsAudioInterfaceInternal::assignPluginDriver(TownsAudioInterface *owner,
 		if (driver && driver != _drv)
 			return false;
 	} else {
-		Common::StackLock lock(_mutex);
 		_drv = driver;
 		_drvOwner = owner;
-		_externalMutex = externalMutexHandling;
 	}
 
 	return true;
 }
 
 void TownsAudioInterfaceInternal::removePluginDriver(TownsAudioInterface *owner) {
-	if (_drvOwner == owner) {
-		Common::StackLock lock(_mutex);
+	Common::StackLock lock(_mutex);
+	if (_drvOwner == owner)
 		_drv = 0;
-	}
 }
 
 void TownsAudioInterfaceInternal::nextTickEx(int32 *buffer, uint32 bufferSize) {
+	Common::StackLock lock(_mutex);
 	if (!_ready)
 		return;
 
@@ -579,11 +582,13 @@ void TownsAudioInterfaceInternal::nextTickEx(int32 *buffer, uint32 bufferSize) {
 }
 
 void TownsAudioInterfaceInternal::timerCallbackA() {
+	Common::StackLock lock(_mutex);
 	if (_drv && _ready)
 		_drv->timerCallback(0);
 }
 
 void TownsAudioInterfaceInternal::timerCallbackB() {
+	Common::StackLock lock(_mutex);
 	if (_ready) {
 		if (_drv)
 			_drv->timerCallback(1);
@@ -1936,8 +1941,8 @@ void TownsAudio_WaveTable::clear() {
 	data = 0;
 }
 
-TownsAudioInterface::TownsAudioInterface(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver, bool externalMutexHandling) {
-	_intf = TownsAudioInterfaceInternal::addNewRef(mixer, this, driver, externalMutexHandling);
+TownsAudioInterface::TownsAudioInterface(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver) {
+	_intf = TownsAudioInterfaceInternal::addNewRef(mixer, this, driver);
 }
 
 TownsAudioInterface::~TownsAudioInterface() {
diff --git a/audio/softsynth/fmtowns_pc98/towns_audio.h b/audio/softsynth/fmtowns_pc98/towns_audio.h
index ba13bd10f6..815875c1ac 100644
--- a/audio/softsynth/fmtowns_pc98/towns_audio.h
+++ b/audio/softsynth/fmtowns_pc98/towns_audio.h
@@ -37,7 +37,7 @@ public:
 
 class TownsAudioInterface {
 public:
-	TownsAudioInterface(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver, bool externalMutexHandling = false);
+	TownsAudioInterface(Audio::Mixer *mixer, TownsAudioInterfacePluginDriver *driver);
 	~TownsAudioInterface();
 
 	enum ErrorCode {
diff --git a/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.cpp b/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.cpp
index 03b4502cda..178d33ef72 100644
--- a/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.cpp
+++ b/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.cpp
@@ -27,9 +27,8 @@
 
 class TownsPC98_FmSynthOperator {
 public:
-	TownsPC98_FmSynthOperator(const uint32 timerbase, const uint32 rtt, const uint8 *rateTable,
-	                          const uint8 *shiftTable, const uint8 *attackDecayTable, const uint32 *frqTable,
-	                          const uint32 *sineTable, const int32 *tlevelOut, const int32 *detuneTable);
+	TownsPC98_FmSynthOperator(const uint32 timerbase, const uint32 rtt, const uint8 *rateTable,	const uint8 *shiftTable,
+		const uint8 *attackDecayTable, const uint32 *frqTable, const uint32 *sineTable, const int32 *tlevelOut, const int32 *detuneTable);
 	~TownsPC98_FmSynthOperator() {}
 
 	void keyOn();
@@ -101,17 +100,15 @@ protected:
 	} fs_a, fs_d, fs_s, fs_r;
 };
 
-TownsPC98_FmSynthOperator::TownsPC98_FmSynthOperator(const uint32 timerbase, const uint32 rtt,
-		const uint8 *rateTable, const uint8 *shiftTable, const uint8 *attackDecayTable,
-		const uint32 *frqTable, const uint32 *sineTable, const int32 *tlevelOut, const int32 *detuneTable) :
-	_rtt(rtt), _rateTbl(rateTable), _rshiftTbl(shiftTable), _adTbl(attackDecayTable), _fTbl(frqTable),
-	_sinTbl(sineTable), _tLvlTbl(tlevelOut), _detnTbl(detuneTable), _tickLength(timerbase * 2),
-	_specifiedAttackRate(0), _specifiedDecayRate(0), _specifiedReleaseRate(0), _envelopeShapeSpecs(0), _specifiedSustainRate(0),
-	_sustainLevel(0), _phase(0), _shapeState(0), _shapeScale(0), _state(kEnvReady), _holdKey(false), _timer(0), _keyScale1(0),
-	_keyScale2(0), _freqTemp(0), _currentLevel(1023), _ampMod(false), _tickCount(0), _phaseIncrement(0) {
+TownsPC98_FmSynthOperator::TownsPC98_FmSynthOperator(const uint32 timerbase, const uint32 rtt, const uint8 *rateTable, const uint8 *shiftTable,
+	const uint8 *attackDecayTable, const uint32 *frqTable, const uint32 *sineTable, const int32 *tlevelOut, const int32 *detuneTable) :
+	_rtt(rtt), _rateTbl(rateTable), _rshiftTbl(shiftTable), _adTbl(attackDecayTable), _fTbl(frqTable), _sinTbl(sineTable),
+	_tLvlTbl(tlevelOut), _detnTbl(detuneTable), _tickLength(timerbase * 2), _specifiedAttackRate(0), _specifiedDecayRate(0),
+	_specifiedReleaseRate(0), _envelopeShapeSpecs(0), _specifiedSustainRate(0), _sustainLevel(0), _phase(0), _shapeState(0),
+	_shapeScale(0), _state(kEnvReady), _holdKey(false), _timer(0), _keyScale1(0), _keyScale2(0), _freqTemp(0),
+	_currentLevel(1023), _ampMod(false), _tickCount(0), _phaseIncrement(0) {
 
 	fs_a.rate = fs_a.shift = fs_d.rate = fs_d.shift = fs_s.rate = fs_s.shift = fs_r.rate = fs_r.shift = 0;
-
 	reset();
 }
 
@@ -199,6 +196,7 @@ void TownsPC98_FmSynthOperator::generateOutput(int32 phasebuf, int32 *feed, int3
 			switch (_state) {
 			case kEnvReady:
 				return;
+
 			case kEnvAttacking:
 				targetLevel = 0;
 				nextState = _sustainLevel ? kEnvDecaying : kEnvSustaining;
@@ -211,18 +209,21 @@ void TownsPC98_FmSynthOperator::generateOutput(int32 phasebuf, int32 *feed, int3
 					continue;
 				}
 				break;
+
 			case kEnvDecaying:
 				targetTime = (1 << fs_d.shift) - 1;
 				nextState = kEnvSustaining;
 				targetLevel = _sustainLevel;
 				levelIncrement = _adTbl[fs_d.rate + ((_tickCount >> fs_d.shift) & 7)] << _shapeScale;
 				break;
+
 			case kEnvSustaining:
 				targetTime = (1 << fs_s.shift) - 1;
 				nextState = kEnvSustaining;
 				targetLevel = _shapeScale ? 832 : 1023;
 				levelIncrement = _adTbl[fs_s.rate + ((_tickCount >> fs_s.shift) & 7)] << _shapeScale;
 				break;
+
 			case kEnvReleasing:
 				targetTime = (1 << fs_r.shift) - 1;
 				nextState = kEnvReady;
@@ -238,8 +239,10 @@ void TownsPC98_FmSynthOperator::generateOutput(int32 phasebuf, int32 *feed, int3
 			if ((_state == kEnvAttacking && _currentLevel <= targetLevel) || (_state != kEnvAttacking && _currentLevel >= targetLevel)) {
 				if (_state != kEnvDecaying)
 					_currentLevel = targetLevel;
+
 				if (_state == kEnvSustaining && _shapeScale) {
 					_currentLevel += 191;
+
 					if (_shapeState & 1) {
 						if (!(_shapeState & 0x10))
 							_shapeState |= 0x40;
@@ -934,7 +937,7 @@ void TownsPC98_FmSynthPercussionSource::advanceInput(RhtChannel *ins) {
 }
 #endif // DISABLE_PC98_RHYTHM_CHANNEL
 
-TownsPC98_FmSynth::TownsPC98_FmSynth(Audio::Mixer *mixer, EmuType type, bool externalMutexHandling) :
+TownsPC98_FmSynth::TownsPC98_FmSynth(Audio::Mixer *mixer, EmuType type) :
 	_mixer(mixer),
 	_chanInternal(0), _ssg(0),
 #ifndef DISABLE_PC98_RHYTHM_CHANNEL
@@ -944,7 +947,7 @@ TownsPC98_FmSynth::TownsPC98_FmSynth(Audio::Mixer *mixer, EmuType type, bool ext
 	_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), _externalMutex(externalMutexHandling), _ready(false) {
+	_volMaskA(0), _volMaskB(0), _volumeA(255), _volumeB(255), _ready(false) {
 
 	memset(&_timers[0], 0, sizeof(ChipTimer));
 	memset(&_timers[1], 0, sizeof(ChipTimer));
@@ -957,11 +960,10 @@ TownsPC98_FmSynth::TownsPC98_FmSynth(Audio::Mixer *mixer, EmuType type, bool ext
 }
 
 TownsPC98_FmSynth::~TownsPC98_FmSynth() {
+	Common::StackLock lock(_mutex);
 	if (_ready)
 		deinit();
 
-	Common::StackLock lock(_mutex);
-
 	delete _ssg;
 #ifndef DISABLE_PC98_RHYTHM_CHANNEL
 	delete _prc;
@@ -1006,8 +1008,7 @@ bool TownsPC98_FmSynth::init() {
 	_timers[0].cb = &TownsPC98_FmSynth::timerCallbackA;
 	_timers[1].cb = &TownsPC98_FmSynth::timerCallbackB;
 
-	_mixer->playStream(Audio::Mixer::kPlainSoundType,
-	                   &_soundHandle, this, -1, Audio::Mixer::kMaxChannelVolume, 0, DisposeAfterUse::NO, true);
+	_mixer->playStream(Audio::Mixer::kPlainSoundType, &_soundHandle, this, -1, Audio::Mixer::kMaxChannelVolume, 0, DisposeAfterUse::NO, true);
 
 	_ready = true;
 
@@ -1015,10 +1016,10 @@ bool TownsPC98_FmSynth::init() {
 }
 
 void TownsPC98_FmSynth::reset() {
+	Common::StackLock lock(_mutex);
 	if (!_ready)
 		return;
 
-	Common::StackLock lock(_mutex);
 	for (int i = 0; i < _numChan; i++) {
 		for (int ii = 0; ii < 4; ii++)
 			_chanInternal[i].opr[ii]->reset();
@@ -1043,6 +1044,7 @@ void TownsPC98_FmSynth::reset() {
 }
 
 void TownsPC98_FmSynth::writeReg(uint8 part, uint8 regAddress, uint8 value) {
+	Common::StackLock lock(_mutex);
 	if (!_ready)
 		return;
 
@@ -1051,8 +1053,6 @@ void TownsPC98_FmSynth::writeReg(uint8 part, uint8 regAddress, uint8 value) {
 		return;
 	}
 
-	Common::StackLock lock(_mutex);
-
 	static const uint8 oprOrdr[] = { 0, 2, 1, 3 };
 
 	_registers[regAddress][part] = value;
@@ -1253,6 +1253,7 @@ void TownsPC98_FmSynth::writeReg(uint8 part, uint8 regAddress, uint8 value) {
 }
 
 uint8 TownsPC98_FmSynth::readReg(uint8 part, uint8 regAddress) {
+	Common::StackLock lock(_mutex);
 	if (!_ready || part > 1)
 		return 0;
 
@@ -1270,18 +1271,13 @@ uint8 TownsPC98_FmSynth::readReg(uint8 part, uint8 regAddress) {
 }
 
 int TownsPC98_FmSynth::readBuffer(int16 *buffer, const int numSamples) {
+	Common::StackLock lock(_mutex);
 	memset(buffer, 0, sizeof(int16) * numSamples);
 	int32 *tmp = new int32[numSamples];
 	int32 *tmpStart = tmp;
 	memset(tmp, 0, sizeof(int32) * numSamples);
 	int32 samplesLeft = numSamples >> 1;
 
-	bool locked = false;
-	if (_ready) {
-		_mutex.lock();
-		locked = true;
-	}
-
 	while (_ready && samplesLeft) {
 		int32 render = samplesLeft;
 
@@ -1289,18 +1285,8 @@ int TownsPC98_FmSynth::readBuffer(int16 *buffer, const int numSamples) {
 			if (_timers[i].enabled && _timers[i].cb) {
 				if (!_timers[i].smpTillCb) {
 
-					if (locked && _externalMutex) {
-						_mutex.unlock();
-						locked = false;
-					}
-
 					(this->*_timers[i].cb)();
 
-					if (!locked && _externalMutex) {
-						_mutex.lock();
-						locked = true;
-					}
-
 					_timers[i].smpTillCb = _timers[i].smpPerCb;
 
 					_timers[i].smpTillCbRem += _timers[i].smpPerCbRem;
@@ -1343,9 +1329,6 @@ int TownsPC98_FmSynth::readBuffer(int16 *buffer, const int numSamples) {
 		tmp += (render << 1);
 	}
 
-	if (locked)
-		_mutex.unlock();
-
 	delete[] tmpStart;
 
 	return numSamples;
@@ -1364,9 +1347,9 @@ int TownsPC98_FmSynth::getRate() const {
 }
 
 void TownsPC98_FmSynth::deinit() {
+	Common::StackLock lock(_mutex);
 	_ready = false;
 	_mixer->stopHandle(_soundHandle);
-	Common::StackLock lock(_mutex);
 	_timers[0].cb = _timers[1].cb = &TownsPC98_FmSynth::idleTimerCallback;
 }
 
@@ -1395,6 +1378,7 @@ void TownsPC98_FmSynth::setVolumeChannelMasks(int channelMaskA, int channelMaskB
 }
 
 void TownsPC98_FmSynth::setLevelSSG(int vol) {
+	Common::StackLock lock(_mutex);
 	if (_ssg)
 		_ssg->setOutputLevel(vol);
 }
diff --git a/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.h b/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.h
index 0c4a77875f..730dbecb16 100644
--- a/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.h
+++ b/audio/softsynth/fmtowns_pc98/towns_pc98_fmsynth.h
@@ -59,7 +59,7 @@ public:
 		kType86
 	};
 
-	TownsPC98_FmSynth(Audio::Mixer *mixer, EmuType type, bool externalMutexHandling = false);
+	TownsPC98_FmSynth(Audio::Mixer *mixer, EmuType type);
 	virtual ~TownsPC98_FmSynth();
 
 	virtual bool init();
@@ -99,7 +99,6 @@ protected:
 	const bool _hasPercussion;
 
 	Common::Mutex _mutex;
-	bool _externalMutex;
 
 private:
 	void generateTables();