From 366d4aec808e291a875351e0d2dedc8c58bc0796 Mon Sep 17 00:00:00 2001
From: Souryo <mesenemu@gmail.com>
Date: Mon, 4 Aug 2014 15:55:20 -0400
Subject: [PATCH] Mapper 189 support

---
 Core/Core.vcxproj         |  1 +
 Core/Core.vcxproj.filters |  3 +++
 Core/MMC3.h               |  8 +++++---
 Core/MMC3_189.h           | 41 +++++++++++++++++++++++++++++++++++++++
 Core/MapperFactory.cpp    |  2 ++
 5 files changed, 52 insertions(+), 3 deletions(-)
 create mode 100644 Core/MMC3_189.h

diff --git a/Core/Core.vcxproj b/Core/Core.vcxproj
index 3687eaa2..729ca40e 100644
--- a/Core/Core.vcxproj
+++ b/Core/Core.vcxproj
@@ -112,6 +112,7 @@
     <ClInclude Include="InputDataMessage.h" />
     <ClInclude Include="MessageType.h" />
     <ClInclude Include="MMC2.h" />
+    <ClInclude Include="MMC3_189.h" />
     <ClInclude Include="Movie.h" />
     <ClInclude Include="MovieDataMessage.h" />
     <ClInclude Include="Nanjing.h" />
diff --git a/Core/Core.vcxproj.filters b/Core/Core.vcxproj.filters
index 8107ea53..614876d1 100644
--- a/Core/Core.vcxproj.filters
+++ b/Core/Core.vcxproj.filters
@@ -188,6 +188,9 @@
     <ClInclude Include="Nanjing.h">
       <Filter>Header Files\Mappers</Filter>
     </ClInclude>
+    <ClInclude Include="MMC3_189.h">
+      <Filter>Header Files\Mappers</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="CPU.cpp">
diff --git a/Core/MMC3.h b/Core/MMC3.h
index f1484c5c..4b304afc 100644
--- a/Core/MMC3.h
+++ b/Core/MMC3.h
@@ -1,3 +1,5 @@
+#pragma once
+
 #include "stdafx.h"
 #include "BaseMapper.h"
 #include "CPU.h"
@@ -61,7 +63,8 @@ class MMC3 : public BaseMapper
 			_wramWriteProtected = false;
 		}
 
-		void UpdateState()
+	protected:
+		virtual void UpdateState()
 		{
 			_currentRegister = _state.Reg8000 & 0x07;
 			_chrMode = (_state.Reg8000 & 0x80) >> 7;
@@ -110,8 +113,7 @@ class MMC3 : public BaseMapper
 
 		}
 
-	protected:
-		void StreamState(bool saving)
+		virtual void StreamState(bool saving)
 		{
 			Stream<uint8_t>(_state.Reg8000);
 			Stream<uint8_t>(_state.RegA000);
diff --git a/Core/MMC3_189.h b/Core/MMC3_189.h
new file mode 100644
index 00000000..c42c28d4
--- /dev/null
+++ b/Core/MMC3_189.h
@@ -0,0 +1,41 @@
+#pragma once
+
+#include "stdafx.h"
+#include "MMC3.h"
+
+class MMC3_189 : public MMC3
+{
+private:
+	uint8_t _prgReg = 0;
+
+	virtual uint16_t RegisterStartAddress() { return 0x4120; }
+	
+	virtual void WriteRegister(uint16_t addr, uint8_t value)
+	{
+		if(addr <= 0x4FFF) {
+			_prgReg = value;
+			UpdateState();
+		} else {
+			MMC3::WriteRegister(addr, value);
+		}
+	}
+
+	virtual void UpdateState()
+	{
+		MMC3::UpdateState();
+
+		//"$4120-7FFF:  [AAAA BBBB]"
+		//" 'A' and 'B' bits of the $4120 reg seem to be effectively OR'd."
+		uint8_t prgPage = (((_prgReg) | (_prgReg >> 4)) & 0x07) * 4;
+		SelectPRGPage(0, prgPage);
+		SelectPRGPage(1, prgPage+1);
+		SelectPRGPage(2, prgPage+2);
+		SelectPRGPage(3, prgPage+3);
+	}
+
+	virtual void StreamState(bool saving)
+	{
+		MMC3::StreamState(saving);
+		Stream<uint8_t>(_prgReg);
+	}
+};
\ No newline at end of file
diff --git a/Core/MapperFactory.cpp b/Core/MapperFactory.cpp
index d8f35f7e..bd41ce61 100644
--- a/Core/MapperFactory.cpp
+++ b/Core/MapperFactory.cpp
@@ -9,6 +9,7 @@
 #include "MMC1.h"
 #include "MMC2.h"
 #include "MMC3.h"
+#include "MMC3_189.h"
 #include "Nanjing.h"
 #include "NROM.h"
 #include "UNROM.h"
@@ -35,6 +36,7 @@ BaseMapper* MapperFactory::GetMapperFromID(uint8_t mapperID)
 		case 27: return new VRC2_4(VRCVariant::VRC4_27);  //Untested
 		case 71: return new UNROM(); //TODO: "It's largely a clone of UNROM, and Camerica games were initially emulated under iNES Mapper 002 before 071 was assigned."
 		case 163: return new Nanjing();
+		case 189: return new MMC3_189();
 		default: Console::DisplayMessage(L"Unsupported mapper, cannot load file.");
 	}