VRC4: Added IRQ support

Core/VRC2_4.h

@@ -1,6 +1,7 @@
 #pragma once
 #include "stdafx.h"
 #include "BaseMapper.h"
+#include "VrcIrq.h"
 
 enum class VRCVariant
 {
@@ -20,6 +21,7 @@ enum class VRCVariant
 class VRC2_4 : public BaseMapper
 {
 	private:
+		VrcIrq _irq;
 		VRCVariant _variant;
 
 		uint8_t _prgReg0;
@@ -40,13 +42,18 @@ class VRC2_4 : public BaseMapper
 			_prgMode = 0;
 			_prgReg0 = 0;
 			_prgReg1 = 0;
-			_hasIRQ = 0;
+			_hasIRQ = false;
 			memset(_loCHRRegs, 0, sizeof(_loCHRRegs));
 			memset(_hiCHRRegs, 0, sizeof(_hiCHRRegs));
 
 			UpdateState();
 		}
 
+		void ProcessCpuClock()
+		{
+			_irq.ProcessCpuClock();
+		}
+
 		void UpdateState()
 		{
 			for(int i = 0; i < 8; i++) {
@@ -99,15 +106,14 @@ class VRC2_4 : public BaseMapper
 					//One reg contains the high 5 bits 
 					_hiCHRRegs[regNumber] = value & 0x1F;
 				}
-			} else if(addr == 0xF000 || addr == 0xF001) {
-				//IRQ Reload Value
-				_hasIRQ = true;
+			} else if(addr == 0xF000) {
+				_irq.SetReloadValueNibble(value, false);
+			} else if(addr == 0xF001) {
+				_irq.SetReloadValueNibble(value, true);
 			} else if(addr == 0xF002) {
-				//IRQ Control
-				_hasIRQ = true;
+				_irq.SetControlValue(value);
 			} else if(addr == 0xF003) {
-				//IRQ Acknowledge
-				_hasIRQ = true;
+				_irq.AcknowledgeIrq();
 			}
 
 			UpdateState();
@@ -186,6 +192,8 @@ class VRC2_4 : public BaseMapper
 
 			Stream<bool>(_hasIRQ);
 
+			Stream(_irq);
+
 			BaseMapper::StreamState(saving);
 		}
 };

Core/VrcIrq.h

@@ -56,6 +56,15 @@ public:
 		_irqReloadValue = value;
 	}
 
+	void SetReloadValueNibble(uint8_t value, bool highBits)
+	{
+		if(highBits) {
+			_irqReloadValue = (_irqReloadValue & 0x0F) | ((value & 0x0F) << 4);
+		} else {
+			_irqReloadValue = (_irqReloadValue & 0xF0) | (value & 0x0F);
+		}
+	}
+
 	void SetControlValue(uint8_t value)
 	{
 		_irqEnabledAfterAck = (value & 0x01) == 0x01;