PCE: More CD-ROM emulation improvements

-ADPCM DMA speed now matches what krikzz's test rom expects
-Implemented some delays in CD-ROM interface that mostly match the test rom
-Implemented delay when software fails to read an entire sectore before the next one is ready (improves audio sync in Sherlock Holmes movies)
-Re-fixed issues with Ys IV that were apparently caused by the read command not properly updating the SCSI signals after the drive starts seeking to the requested sector
-Fixed some ADPCM playback flags/timing issues based on okitest test rom (playing/busy flag gets turned off slightly delayed vs end reached flag, etc.)
-Implemented delay for $1805 writes, based on test rom

Core/PCE/CdRom/PceAdpcm.cpp

@@ -38,7 +38,6 @@ void PceAdpcm::Reset()
 	_state.ReadAddress = 0;
 	_state.WriteAddress = 0;
 	_state.AddressPort = 0;
-	_state.Playing = false;
 	SetEndReached(false);
 	SetHalfReached(false);
 	_state.AdpcmLength = 0;
@@ -86,17 +85,10 @@ void PceAdpcm::ProcessFlags()
 	}
 
 	if(_state.Control & 0x80) {
-		LogDebug("[ADPCM] Reset");
 		Reset();
 	}
 
-	if(!(_state.Control & 0x20)) {
-		_state.Playing = false;
-		LogDebugIf(_state.Playing, "[ADPCM] Stop");
-	} else if(!_state.Playing) {
-		LogDebug("[ADPCM] Play");
-		_state.Playing = true;
-		_currentOutput = 2048;
+	if(_state.Control & 0x20) {
 		_needExec = true;
 	}
 }
@@ -115,7 +107,6 @@ void PceAdpcm::SetControl(uint8_t value)
 
 	_state.Control = value;
 	ProcessFlags();
-
 }
 
 void PceAdpcm::ProcessReadOperation()
@@ -126,7 +117,7 @@ void PceAdpcm::ProcessReadOperation()
 		_emu->ProcessMemoryAccess<CpuType::Pce, MemoryType::PceAdpcmRam, MemoryOperationType::Read>(_state.ReadAddress, _state.ReadBuffer);
 		_state.ReadAddress++;
 
-		if(!IsLengthLatchEnabled() && !_state.EndReached) {
+		if(!IsLengthLatchEnabled()) {
 			if(_state.AdpcmLength > 0) {
 				_state.AdpcmLength--;
 				SetHalfReached(_state.AdpcmLength < 0x8000);
@@ -159,18 +150,27 @@ void PceAdpcm::ProcessWriteOperation()
 
 void PceAdpcm::ProcessDmaRequest()
 {
-	if(!_scsi->CheckSignal(Ack) && !_scsi->CheckSignal(Cd) && _scsi->CheckSignal(Io) && _scsi->CheckSignal(Req)) {
-		_needExec = true;
-		_state.WriteClockCounter = GetClocksToNextSlot(false);
-		_state.WriteBuffer = _scsi->GetDataPort();
-		_scsi->SetAckWithAutoClear();
-	}
-
-	if(!_scsi->IsDataBlockReady()) {
-		//Reset bit 0 only
-		//Resetting bit 1 breaks Record of Lodoss War (freezes when start is pressed)
-		//Not resetting bit 0 breaks Seiya Monogatari - Anearth (freezes on logo)
-		_state.DmaControl &= ~0x01;
+	if(_dmaWriteCounter) {
+		if(--_dmaWriteCounter == 0) {
+			if(!_state.WriteClockCounter) {
+				_state.WriteClockCounter = GetClocksToNextSlot(false);
+				_state.WriteBuffer = _scsi->GetDataPort();
+				_scsi->SetAckWithAutoClear();
+
+				if(!_scsi->IsDataBlockReady()) {
+					//Reset bit 0 only
+					//Resetting bit 1 breaks Record of Lodoss War (freezes when start is pressed)
+					//Not resetting bit 0 breaks Seiya Monogatari - Anearth (freezes on logo)
+					_state.DmaControl &= ~0x01;
+				}
+			} else {
+				_dmaWriteCounter++;
+			}
+		}
+	} else if(!_scsi->CheckSignal(Ack) && !_scsi->CheckSignal(Cd) && _scsi->CheckSignal(Io) && _scsi->CheckSignal(Req)) {
+		//Some delay is required here according to test rom
+		//Valid range is 10-14 (higher or lower fails the test)
+		_dmaWriteCounter = 12;
 	}
 }
 
@@ -195,7 +195,7 @@ void PceAdpcm::Exec()
 	//Called every 3 master clocks
 	ProcessFlags();
 
-	if(_state.Playing) {
+	if(_state.Playing || (_state.Control & 0x20)) {
 		_nextSampleCounter += 3;
 		if(_nextSampleCounter >= _clocksPerSample) {
 			PlaySample();
@@ -212,13 +212,13 @@ void PceAdpcm::Exec()
 	}
 
 	bool dmaRequested = (_state.DmaControl & 0x03) != 0;
-	if(dmaRequested && !_state.WriteClockCounter) {
+	if(dmaRequested) {
 		ProcessDmaRequest();
 	}
 
 	ProcessFlags();
 
-	_needExec = _state.Playing || _state.ReadClockCounter > 0 || _state.WriteClockCounter > 0 || dmaRequested;
+	_needExec = _state.Playing || (_state.Control & 0x20) || _state.ReadClockCounter || _state.WriteClockCounter || dmaRequested || _dmaWriteCounter;
 }
 
 void PceAdpcm::Write(uint16_t addr, uint8_t value)
@@ -291,15 +291,30 @@ void PceAdpcm::PlaySample()
 {
 	if(_state.Control & 0x80) {
 		//Reset flag is enabled
+		_state.Playing = (_state.Control & 0x20) != 0;
 		return;
 	}
 
+	if((_state.Control & 0x40) && _state.AdpcmLength == 0) {
+		_state.Control &= ~0x20;
+	}
+
+	if(!(_state.Control & 0x20)) {
+		_state.Playing = false;
+		return;
+	}
+
+	if(!_state.Playing) {
+		_state.Playing = true;
+		_currentOutput = 2048;
+	}
+
 	uint8_t data;
 	if(_state.Nibble) {
 		_state.Nibble = false;
 		data = _ram[_state.ReadAddress] & 0x0F;
 		_state.ReadAddress++;
-		_state.AdpcmLength--;
+		_state.AdpcmLength = (_state.AdpcmLength - 1) & 0x1FFFF;
 	} else {
 		_state.Nibble = true;
 		data = (_ram[_state.ReadAddress] >> 4) & 0x0F;
@@ -315,8 +330,6 @@ void PceAdpcm::PlaySample()
 
 	SetHalfReached(_state.AdpcmLength <= 0x8000);
 	if(_state.AdpcmLength == 0) {
-		_state.Playing = false;
-		_state.Control &= ~0x20; //disable play flag in control register
 		SetEndReached(true);
 	}
 
@@ -359,6 +372,7 @@ void PceAdpcm::Serialize(Serializer& s)
 	SV(_magnitude);
 	SV(_clocksPerSample);
 	SV(_nextSampleCounter);
+	SV(_dmaWriteCounter);
 
 	if(!s.IsSaving()) {
 		_needExec = true;

Core/PCE/CdRom/PceAdpcm.h

@@ -25,8 +25,9 @@ class PceAdpcm final : public IAudioProvider, public ISerializable
 	vector<int16_t> _samplesToPlay;
 	int16_t _currentOutput = 0;
 	uint8_t _magnitude = 0;
+	uint8_t _dmaWriteCounter = 0;
 	bool _needExec = true;
-	
+
 	double _clocksPerSample = PceConstants::MasterClockRate / 32000.0;
 	double _nextSampleCounter = 0;
 

Core/PCE/CdRom/PceCdRom.cpp

@@ -160,8 +160,14 @@ void PceCdRom::Write(uint16_t addr, uint8_t value)
 		}
 
 		case 0x05:
-			_state.ReadRightChannel = !_state.ReadRightChannel;
-			_state.AudioSampleLatch = _state.ReadRightChannel ? _audioPlayer.GetRightSample() : _audioPlayer.GetLeftSample();
+			if(_console->GetMasterClock() >= _latchChannelStamp) {
+				//Prevent multiple calls in a row - the delay is required to pass test rom
+				//The value of the L/R flag changes immediately, and writing to the register
+				//again within a short timeframe appears to be ignored.
+				_state.ReadRightChannel = !_state.ReadRightChannel;
+				_state.AudioSampleLatch = _state.ReadRightChannel ? _audioPlayer.GetRightSample() : _audioPlayer.GetLeftSample();
+				_latchChannelStamp = _console->GetMasterClock() + 700; //less than a 700 clock delay causes the test to fail
+			}
 			break;
 
 		case 0x06: break; //readonly
@@ -260,6 +266,8 @@ void PceCdRom::Serialize(Serializer& s)
 	SVArray(_saveRam, _saveRamSize);
 	SVArray(_cdromRam, _cdromRamSize);
 
+	SV(_latchChannelStamp);
+
 	SV(_scsi);
 	SV(_adpcm);
 	SV(_audioPlayer);

Core/PCE/CdRom/PceCdRom.h

@@ -25,7 +25,8 @@ class PceCdRom final : public ISerializable
 	PceAudioFader _audioFader;
 	PceCdAudioPlayer _audioPlayer;
 	PceCdRomState _state = {};
-
+	uint64_t _latchChannelStamp = 0;
+
 	uint8_t* _cdromRam = nullptr;
 	uint32_t _cdromRamSize = 0;
 	uint8_t* _saveRam = nullptr;

Core/PCE/CdRom/PceCdSeekDelay.h

@@ -62,13 +62,12 @@ class PceCdSeekDelay
 			trackGap += (1606.48 * (src - dst - 1));
 		}
 
-		constexpr double shortSeekFactor = 1.45; //A 1.45 factor allows both Ys IV and F1 Team Simulation to work properly
 		if(lbaGap < 2) {
-			return shortSeekFactor * (3 * 1000 / 60);
+			return 3 * 1000 / 60;
 		} else if(lbaGap < 5) {
-			return shortSeekFactor * ((9 * 1000 / 60) + (_sectorList[dst].RotationMs / 2));
+			return (9 * 1000 / 60) + (_sectorList[dst].RotationMs / 2);
 		} else if(trackGap <= 80) {
-			return shortSeekFactor * ((16 * 1000 / 60) + (_sectorList[dst].RotationMs / 2));
+			return (16 * 1000 / 60) + (_sectorList[dst].RotationMs / 2);
 		} else if(trackGap <= 160) {
 			return (22 * 1000 / 60) + (_sectorList[dst].RotationMs / 2);
 		} else if(trackGap <= 644) {