Open Bus: Fixes to open bus implementation - fixes allpads-r2a test result

Core/ControlManager.cpp

@@ -177,7 +177,7 @@ uint8_t ControlManager::GetPortValue(uint8_t port)
 	//"In the NES and Famicom, the top three (or five) bits are not driven, and so retain the bits of the previous byte on the bus. 
 	//Usually this is the most significant byte of the address of the controller port - 0x40.
 	//Paperboy relies on this behavior and requires that reads from the controller ports return exactly $40 or $41 as appropriate."
-	uint8_t value = 0x40;
+	uint8_t value = MemoryManager::GetOpenBus(0xE0);
 	if(device) {
 		value |= device->GetPortOutput();
 	}

Core/FDS.cpp

@@ -307,8 +307,7 @@ uint8_t FDS::ReadRegister(uint16_t addr)
 		}
 	}
 
-	//Return open bus
-	return (addr & 0xFF00) >> 8;
+	return MemoryManager::GetOpenBus();
 }
 
 void FDS::StreamState(bool saving)

Core/FdsAudio.h

@@ -93,8 +93,7 @@ public:
 			}
 		}
 
-		//Open bus
-		return (addr >> 8);
+		return MemoryManager::GetOpenBus();
 	}
 
 	void WriteRegister(uint16_t addr, uint8_t value)

Core/MMC5.h

@@ -510,7 +510,6 @@ protected:
 			case 0x5206: return (_multiplierValue1*_multiplierValue2) >> 8;
 		}
 
-		//Open bus
-		return (addr >> 8);
+		return MemoryManager::GetOpenBus();
 	}
 };

Core/MMC5Audio.h

@@ -111,8 +111,7 @@ public:
 				return status;
 		}
 
-		//Open bus
-		return (addr >> 8);
+		return MemoryManager::GetOpenBus();
 	}
 
 	void WriteRegister(uint16_t addr, uint8_t value)

Core/MemoryManager.cpp

@@ -4,9 +4,13 @@
 #include "Debugger.h"
 #include "CheatManager.h"
 
+//Used for open bus
+uint8_t MemoryManager::_lastReadValue = 0;
+
 MemoryManager::MemoryManager(shared_ptr<BaseMapper> mapper)
 {
 	_mapper = mapper;
+	_lastReadValue = 0;
 
 	_internalRAM = new uint8_t[InternalRAMSize];
 	for(int i = 0; i < 2; i++) {
@@ -49,7 +53,7 @@ uint8_t MemoryManager::ReadRegister(uint16_t addr)
 	if(_ramReadHandlers[addr]) {
 		return _ramReadHandlers[addr]->ReadRAM(addr);
 	} else {
-		return (addr & 0xFF00) >> 8;
+		return GetOpenBus();
 	}
 }
 
@@ -94,6 +98,7 @@ uint8_t MemoryManager::DebugRead(uint16_t addr)
 	}
 
 	CheatManager::ApplyRamCodes(addr, value);
+
 	return value;
 }
 
@@ -115,6 +120,8 @@ uint8_t MemoryManager::Read(uint16_t addr, MemoryOperationType operationType)
 
 	Debugger::ProcessRamOperation(operationType, addr, value);
 
+	_lastReadValue = value;
+
 	return value;
 }
 
@@ -175,4 +182,9 @@ void MemoryManager::StreamState(bool saving)
 	ArrayInfo<uint8_t> nameTable0Ram = { _nametableRAM[0], MemoryManager::NameTableScreenSize };
 	ArrayInfo<uint8_t> nameTable1Ram = { _nametableRAM[1], MemoryManager::NameTableScreenSize };
 	Stream(internalRam, nameTable0Ram, nameTable1Ram);
+}
+
+uint8_t MemoryManager::GetOpenBus(uint8_t mask)
+{
+	return _lastReadValue & mask;
 }

Core/MemoryManager.h

@@ -14,6 +14,8 @@ class MemoryManager: public Snapshotable
 		static const int VRAMSize = 0x4000;
 		static const int NameTableScreenSize = 0x400;
 
+		static uint8_t _lastReadValue;
+
 		shared_ptr<BaseMapper> _mapper;
 
 		uint8_t *_internalRAM;
@@ -51,5 +53,7 @@ class MemoryManager: public Snapshotable
 		void WriteVRAM(uint16_t addr, uint8_t value);
 
 		uint32_t ToAbsoluteChrAddress(uint16_t vramAddr);
+
+		static uint8_t GetOpenBus(uint8_t mask = 0xFF);
 };
 

Core/NsfMapper.cpp

@@ -289,8 +289,7 @@ uint8_t NsfMapper::ReadRegister(uint16_t addr)
 		}
 	}
 
-	//Open bus
-	return (addr >> 8);
+	return MemoryManager::GetOpenBus();
 }
 
 void NsfMapper::WriteRegister(uint16_t addr, uint8_t value)