sketch out some thoughts regarding breakpoints

BizHawk.Emulation/Consoles/Nintendo/NES/Core.cs

@@ -211,6 +211,14 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			//apply freeze
 			if (sysbus_freeze[addr].IsFrozen) ret = sysbus_freeze[addr].value;
 
+			//handle breakpoints and stuff.
+			//the idea is that each core can implement its own watch class on an address which will track all the different kinds of monitors and breakpoints and etc.
+			//but since freeze is a common case, it was implemented through its own mechanisms
+			if (sysbus_freeze[addr].HasWatch)
+			{
+				(sysbus_freeze[addr].watch as NESWatch).Read();
+			}
+
 			return ret;
 		}
 

BizHawk.Emulation/Consoles/Nintendo/NES/NES.cs

@@ -34,6 +34,16 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			SetPalette(Palettes.FCEUX_Standard);
 		}
 
+		class NESWatch
+		{
+			public Action OnRead;
+
+			public void Read()
+			{
+				if (OnRead != null) OnRead();
+			}
+		}
+
 		public enum EMirrorType
 		{
 			Vertical, Horizontal,
@@ -183,6 +193,13 @@ namespace BizHawk.Emulation.Consoles.Nintendo
 			SystemBus.GetFreeze = addr => sysbus_freeze[addr];
 			SystemBus.SetFreeze = (addr,value) => sysbus_freeze[addr] = value;
 
+			//demo a watchpoint
+			var test = new NESWatch();
+			test.OnRead = () => Console.WriteLine("0x8000 was read!");
+			MemoryDomain.FreezeData temp = SystemBus.GetFreeze(0x8000);
+			temp.SetWatch(test);
+			SystemBus.SetFreeze(0x8000,temp);
+
             domains.Add(RAM);
 			domains.Add(SystemBus);
             domains.Add(PPUBus);

BizHawk.Emulation/Interfaces/IEmulator.cs

@@ -48,22 +48,31 @@ namespace BizHawk
         public readonly int Size;
         public readonly Endian Endian;
 
+		//perhaps inconveniently, this is a struct. 
+		//this is a premature optimization, since I anticipate having millions of these and i didnt want millions of objects
 		public struct FreezeData
 		{
 			public FreezeData(Flag flags, byte value)
 			{
 				this.flags = flags;
 				this.value = value;
+				watch = null;
 			}
 			public byte value;
 			public Flag flags;
+			public object watch;
+			public void SetWatch(object watch)
+			{
+				this.watch = watch;
+			}
 			public enum Flag : byte
 			{
 				None = 0,
 				Frozen = 1
 			}
 
-			public bool IsFrozen { get { return flags != Flag.None; } }
+			public bool IsFrozen { get { return (flags & Flag.Frozen) != 0; } }
+			public bool HasWatch { get { return watch != null; } }
 			public static FreezeData Unfrozen { get { return new FreezeData(); } }
 		}