From c5d6fad0e19f41696b497654a0b4efbabc72c136 Mon Sep 17 00:00:00 2001
From: saxxonpike <saxxonpike@gmail.com>
Date: Thu, 15 Nov 2012 07:41:59 +0000
Subject: [PATCH] commodore64: CIA timer underflow interrupts implemented
 (BASIC now works)

---
 .../Computers/Commodore64/C64.core.cs         |  1 +
 .../Computers/Commodore64/C64.cs              |  2 ++
 .../Computers/Commodore64/Cia.cs              | 31 +++++++++++++++++++
 3 files changed, 34 insertions(+)

diff --git a/BizHawk.Emulation/Computers/Commodore64/C64.core.cs b/BizHawk.Emulation/Computers/Commodore64/C64.core.cs
index ee0c4ade09..78eb1f66ef 100644
--- a/BizHawk.Emulation/Computers/Commodore64/C64.core.cs
+++ b/BizHawk.Emulation/Computers/Commodore64/C64.core.cs
@@ -71,6 +71,7 @@ namespace BizHawk.Emulation.Computers.Commodore64
 
 			// initialize cpu hard reset vector
 			cpu.PC = (ushort)(ReadMemory(0xFFFC) + (ReadMemory(0xFFFD) << 8));
+			cpu.BCD_Enabled = true;
 
 			// initailize input
 			input = new Input( new DataPortConnector[] { cia0.ConnectPort(0), cia0.ConnectPort(1) } );
diff --git a/BizHawk.Emulation/Computers/Commodore64/C64.cs b/BizHawk.Emulation/Computers/Commodore64/C64.cs
index 5cecb6be53..0139966dc8 100644
--- a/BizHawk.Emulation/Computers/Commodore64/C64.cs
+++ b/BizHawk.Emulation/Computers/Commodore64/C64.cs
@@ -103,7 +103,9 @@ namespace BizHawk.Emulation.Computers.Commodore64
 				if (diskDriveAttached)
 					diskDrive.PerformCycle();
 				cia0.PerformCycle();
+				signal.CiaIRQ0 = cia0.IRQ;
 				cia1.PerformCycle();
+				signal.CiaIRQ1 = cia1.IRQ;
 			}
 
 			if (_islag)
diff --git a/BizHawk.Emulation/Computers/Commodore64/Cia.cs b/BizHawk.Emulation/Computers/Commodore64/Cia.cs
index b390ed6e3d..0e903e2524 100644
--- a/BizHawk.Emulation/Computers/Commodore64/Cia.cs
+++ b/BizHawk.Emulation/Computers/Commodore64/Cia.cs
@@ -13,6 +13,10 @@ namespace BizHawk.Emulation.Computers.Commodore64
 		public int ALARMMIN; // alarm minutes
 		public bool ALARMPM; // alarm AM/PM
 		public int ALARMSEC; // alarm seconds
+		public bool EIALARM; // enable alarm interrupt (internal)
+		public bool EIFLAG; // enable flag pin interrupt (internal)
+		public bool EISP; // enable shift register interrupt (internal)
+		public bool[] EIT = new bool[2]; // enable timer interrupt (internal)
 		public bool IALARM; // alarm interrupt triggered
 		public bool IFLG; // interrupt triggered on FLAG pin
 		public int[] INMODE = new int[2]; // timer input mode
@@ -348,6 +352,14 @@ namespace BizHawk.Emulation.Computers.Commodore64
 			todCounter = todFrequency;
 		}
 
+		public bool IRQ
+		{
+			get
+			{
+				return regs.IRQ;
+			}
+		}
+
 		public byte Peek(int addr)
 		{
 			addr &= 0xF;
@@ -394,6 +406,8 @@ namespace BizHawk.Emulation.Computers.Commodore64
 					}
 				}
 			}
+
+			UpdateInterrupt();
 		}
 
 		public void Poke(int addr, byte val)
@@ -463,6 +477,7 @@ namespace BizHawk.Emulation.Computers.Commodore64
 				underflow[index] = false;
 			}
 
+			regs.IT[index] |= underflow[index];
 			regs.T[index] = timer;
 		}
 
@@ -488,6 +503,17 @@ namespace BizHawk.Emulation.Computers.Commodore64
 			}
 		}
 
+		public void UpdateInterrupt()
+		{
+			bool irq = false;
+			irq |= (regs.EIT[0] & regs.IT[0]);
+			irq |= (regs.EIT[1] & regs.IT[1]);
+			irq |= (regs.EIFLAG & regs.IFLG);
+			irq |= (regs.EISP & regs.ISP);
+			irq |= (regs.EIALARM & regs.IALARM);
+			regs.IRQ = irq;
+		}
+
 		public void Write(ushort addr, byte val)
 		{
 			addr &= 0xF;
@@ -550,6 +576,11 @@ namespace BizHawk.Emulation.Computers.Commodore64
 					intMask &= ~val;
 					if ((val & 0x80) != 0x00)
 						intMask ^= val;
+					regs.EIT[0] = ((intMask & 0x01) != 0x00);
+					regs.EIT[1] = ((intMask & 0x02) != 0x00);
+					regs.EIALARM = ((intMask & 0x04) != 0x00);
+					regs.EISP = ((intMask & 0x08) != 0x00);
+					regs.EIFLAG = ((intMask & 0x10) != 0x00);
 					break;
 				default:
 					regs[addr] = val;