From 37139822ac3f7911f0b2ed2edc8267a1eb6a441a Mon Sep 17 00:00:00 2001
From: adelikat <adelikat@tasvideos.org>
Date: Wed, 9 Apr 2014 01:57:45 +0000
Subject: [PATCH] Atari 2600 - slight fix to m3F, attempt to fix 3E, the mapper
 is still broken, I guess, the only Roms that use it are a Boulder Dash wip
 that is broken, and a Boulder Dash Intro Tune that seems to fail.

---
 .../Consoles/Atari/2600/Mappers/m3E.cs        | 104 ++++++++----------
 .../Consoles/Atari/2600/Mappers/m3F.cs        |   2 +-
 2 files changed, 44 insertions(+), 62 deletions(-)

diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3E.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3E.cs
index c7f35c9d31..73d40f540b 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3E.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3E.cs
@@ -20,26 +20,26 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 	enough space for 256K of RAM.  When RAM is selected, 1000-13FF is the read port while
 	1400-17FF is the write port.
 	*/
-	internal class m3E : MapperBase 
+	internal class m3E : MapperBase
 	{
-		private int _lowbank_2K;
-		private int _rambank_1K;
+		private int _lowbank2K;
+		private int _rambank1K;
 		private bool _hasRam;
 		private ByteBuffer _ram = new ByteBuffer(256 * 1024); // Up to 256k
 
 		public override void SyncState(Serializer ser)
 		{
 			base.SyncState(ser);
-			ser.Sync("lowbank_2k", ref _lowbank_2K);
-			ser.Sync("rambank_1k", ref _rambank_1K);
+			ser.Sync("lowbank_2k", ref _lowbank2K);
+			ser.Sync("rambank_1k", ref _rambank1K);
 			ser.Sync("cart_ram", ref _ram);
 			ser.Sync("hasRam", ref _hasRam);
 		}
 
 		public override void HardReset()
 		{
-			_lowbank_2K = 0;
-			_rambank_1K = 0;
+			_lowbank2K = 0;
+			_rambank1K = 0;
 			_hasRam = false;
 			_ram = new ByteBuffer(256 * 1024);
 			base.HardReset();
@@ -57,25 +57,25 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 			{
 				return base.ReadMemory(addr);
 			}
-			
-			if (addr < 0x17FF) // Low 2k Bank
+
+			if (addr < 0x1800) // Low 2k Bank
 			{
 				if (_hasRam)
 				{
-					if (addr < 0x13FF)
+					if (addr < 0x1400)
 					{
-						return _ram[(addr & 0x03FF) + (_rambank_1K << 10)];
+						return _ram[(addr & 0x03FF) + (_rambank1K << 10)];
 					}
 
-					return _ram[(addr & 0x03FF) + (_rambank_1K << 10)] = 0xFF; // Reading from the write port triggers an unwanted write
+					return _ram[(addr & 0x03FF) + (_rambank1K << 10)] = 0xFF; // Reading from the write port triggers an unwanted write
 				}
-				
-				return Core.Rom[(_lowbank_2K << 11) + (addr & 0x07FF)];
+
+				return Core.Rom[(_lowbank2K << 11) + (addr & 0x07FF)];
 			}
-			
+
 			if (addr < 0x2000) // High bank fixed to last 2k of ROM
 			{
-				return Core.Rom[(Core.Rom.Length - 2048) + (addr & 0x07FF)];
+				return Core.Rom[(Core.Rom.Length - 0x800) + (addr & 0x07FF)];
 			}
 
 			return base.ReadMemory(addr);
@@ -83,56 +83,38 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 
 		public override byte PeekMemory(ushort addr)
 		{
-			if (addr < 0x1000)
-			{
-				return base.ReadMemory(addr);
-			}
-			
-			if (addr < 0x17FF) // Low 2k Bank
-			{
-				if (_hasRam)
-				{
-					if (addr < 0x13FF)
-					{
-						return _ram[(addr & 0x03FF) + (_rambank_1K << 10)];
-					}
-
-					return _ram[(addr & 0x03FF) + (_rambank_1K << 10)]; // Reading from the write port triggers an unwanted write
-				}
-				
-				return Core.Rom[(_lowbank_2K << 11) + (addr & 0x07FF)];
-			}
-			
-			if (addr < 0x2000) // High bank fixed to last 2k of ROM
-			{
-				return Core.Rom[(Core.Rom.Length - 2048) + (addr & 0x07FF)];
-			}
-
-			return base.ReadMemory(addr);
+			return ReadMemory(addr);
 		}
 
 		public override void WriteMemory(ushort addr, byte value)
 		{
+			if (addr == 0x003E)
+			{
+				_hasRam = true;
+				_rambank1K = value;
+				if (_rambank1K > 0)
+				{
+					int xxx = 0;
+					xxx++;
+					int yyy = xxx;
+					yyy++;
+				}
+			}
+			else if (addr < 0x0040)
+			{
+				_hasRam = false;
+				if ((value << 11) < Core.Rom.Length)
+				{
+					_lowbank2K = value;
+				}
+				else
+				{
+					_lowbank2K = value & (Core.Rom.Length >> 11);
+				}
+			}
+
 			if (addr < 0x1000)
 			{
-				if (addr == 0x003E)
-				{
-					_hasRam = true;
-					_rambank_1K = value;
-				}
-				else if (addr == 0x003F)
-				{
-					_hasRam = false;
-					if ((value << 11) < Core.Rom.Length)
-					{
-						_lowbank_2K = value;
-					}
-					else
-					{
-						_lowbank_2K = value & (Core.Rom.Length >> 11);
-					}
-				}
-
 				base.WriteMemory(addr, value);
 			}
 			else if (addr < 0x1400)
@@ -141,7 +123,7 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 			}
 			else if (addr < 0x1800) // Write port
 			{
-				_ram[(_rambank_1K << 10) + (addr & 0x3FF)] = value;
+				_ram[(_rambank1K << 10) + (addr & 0x3FF)] = value;
 			}
 		}
 	}
diff --git a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3F.cs b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3F.cs
index e37a028b84..9454c68743 100644
--- a/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3F.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Atari/2600/Mappers/m3F.cs
@@ -44,7 +44,7 @@ namespace BizHawk.Emulation.Cores.Atari.Atari2600
 				return base.ReadMemory(addr);
 			}
 			
-			if (addr < 0x17FF) // Low 2k Bank
+			if (addr < 0x1800) // Low 2k Bank
 			{
 				return Core.Rom[(_lowbank2K << 11) + (addr & 0x07FF)];
 			}