CPU: Enabling 8-bit indexes must truncate the value of X/Y (refix)

Core/Cpu.Instructions.cpp

@@ -402,10 +402,10 @@ void Cpu::JSR()
 void Cpu::RTI()
 {
 	if(_state.EmulationMode) {
-		_state.PS = PopByte(); //TODO: incorrect
+		SetPS(PopByte());
 		_state.PC = PopWord();
 	} else {
-		_state.PS = PopByte(); //TODO: incorrect
+		SetPS(PopByte());
 		_state.PC = PopWord();
 		_state.K = PopByte();
 	}
@@ -699,9 +699,9 @@ void Cpu::PLP()
 {
 	//"For PLP, (all of) the flags are pulled from the stack. Note that when the e flag is 1, the m and x flag are forced to 1, so after the PLP, both flags will still be 1 no matter what value is pulled from the stack."
 	if(_state.EmulationMode) {
-		_state.PS = PopByte() | ProcFlags::MemoryMode8 | ProcFlags::IndexMode8;
+		SetPS(PopByte() | ProcFlags::MemoryMode8 | ProcFlags::IndexMode8);
 	} else {
-		_state.PS = PopByte();
+		SetPS(PopByte());
 	}
 }
 
@@ -971,9 +971,7 @@ void Cpu::XCE()
 	_state.EmulationMode = carry;
 
 	if(_state.EmulationMode) {
-		SetFlags(ProcFlags::IndexMode8 | ProcFlags::MemoryMode8);
+		SetPS(_state.PS | ProcFlags::IndexMode8 | ProcFlags::MemoryMode8);
-		_state.Y &= 0xFF;
-		_state.X &= 0xFF;
 		_state.SP = 0x100 | (_state.SP & 0xFF);
 	}
 }

Core/Cpu.cpp

@@ -326,6 +326,16 @@ void Cpu::SetSP(uint16_t sp)
 	}
 }
 
+void Cpu::SetPS(uint8_t ps)
+{
+	_state.PS = ps;
+	if(CheckFlag(ProcFlags::IndexMode8)) {
+		//Truncate X/Y when 8-bit indexes are enabled
+		_state.Y &= 0xFF;
+		_state.X &= 0xFF;
+	}
+}
+
 void Cpu::SetRegister(uint8_t &reg, uint8_t value)
 {
 	SetZeroNegativeFlags(value);

Core/Cpu.h

@@ -54,6 +54,7 @@ private:
 	uint32_t FetchEffectiveAddress();
 
 	void SetSP(uint16_t sp);
+	void SetPS(uint8_t ps);
 
 	void SetRegister(uint8_t &reg, uint8_t value);
 	void SetRegister(uint16_t &reg, uint16_t value, bool eightBitMode);