NES: Fixed EPSM issues when using "long writes"

The OUT1 pin was using bit 1 of the data bus, which is incorrect (should match the last value writting to 4016)
SourMesen · Oct 15, 2024 · 6ea096b · 6ea096b
1 parent b9d0c0b
commit 6ea096b
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Showing 3 changed files with 13 additions and 11 deletions.
diff --git a/Core/NES/Epsm.cpp b/Core/NES/Epsm.cpp
@@ -18,23 +18,25 @@ Epsm::~Epsm()
 	_emu->GetSoundMixer()->UnregisterAudioProvider(this);
 }
 
-void Epsm::Write(uint8_t value)
+void Epsm::Write(uint8_t dataBus, uint8_t outPins)
 {
 	//4016 writes
-	bool isHigh = (value & 0x02);
-	bool wasHigh = (_prevValue & 0x02);
+	//The EPSM uses the value of the data bus + the OUT1 pin
+	//The OUT1 can be delayed by a cycle, but not the data bus
+	bool isHigh = (outPins & 0x02);
+	bool wasHigh = (_prevOutPins & 0x02);
 
 	if(isHigh && !wasHigh) {
 		//rising edge
-		_data = (value & 0xF0) | (_data & 0x0F);
-		_addr = ((value & 0x04) >> 1) | ((value & 0x08) >> 3);
+		_data = (dataBus & 0xF0) | (_data & 0x0F);
+		_addr = ((dataBus & 0x04) >> 1) | ((dataBus & 0x08) >> 3);
 	} else if(!isHigh && wasHigh) {
 		//falling edge
-		_data = (_data & 0xF0) | ((value & 0xF0) >> 4);
+		_data = (_data & 0xF0) | ((dataBus & 0xF0) >> 4);
 		_opn.Write(_addr, _data);
 	}
 
-	_prevValue = value;
+	_prevOutPins = outPins;
 }
 
 void Epsm::WriteRam(uint16_t addr, uint8_t value)
@@ -98,7 +100,7 @@ uint8_t Epsm::ReadRam(uint16_t addr)
 void Epsm::Serialize(Serializer& s)
 {
 	SV(_clockCounter);
-	SV(_prevValue);
+	SV(_prevOutPins);
 	SV(_addr);
 	SV(_data);
 	SV(_masterClockRate);

diff --git a/Core/NES/Epsm.h b/Core/NES/Epsm.h
@@ -22,7 +22,7 @@ class Epsm : public IAudioProvider, public INesMemoryHandler, public ISerializab
 	uint64_t _masterClockRate = 0;
 	uint64_t _clockCounter = 0;
 	uint8_t _sampleClockCounter = 0;
-	uint8_t _prevValue = 0;
+	uint8_t _prevOutPins = 0;
 	uint8_t _data = 0;
 	uint8_t _addr = 0;
 
@@ -32,7 +32,7 @@ class Epsm : public IAudioProvider, public INesMemoryHandler, public ISerializab
 	Epsm(Emulator* emu, NesConsole* console, vector<uint8_t>& adpcmRom);
 	~Epsm();
 
-	void Write(uint8_t value);
+	void Write(uint8_t dataBus, uint8_t outPins);
 	void WriteRam(uint16_t addr, uint8_t value) override;
 	void Exec();
 

diff --git a/Core/NES/NesControlManager.cpp b/Core/NES/NesControlManager.cpp
@@ -261,7 +261,7 @@ void NesControlManager::ProcessWrites()
 {
 	if(_writePending && --_writePending == 0) {
 		if(_console->GetEpsm() && _writeAddr == 0x4016) {
-			_console->GetEpsm()->Write(_console->GetMemoryManager()->GetOpenBus());
+			_console->GetEpsm()->Write(_console->GetMemoryManager()->GetOpenBus(), _writeValue);
 		}
 
 		for(shared_ptr<BaseControlDevice>& device : _controlDevices) {