From a4c6b9f5ef453c1155e6ead4971fe6b70ff01587 Mon Sep 17 00:00:00 2001
From: Souryo <mesenemu@gmail.com>
Date: Sat, 13 Aug 2016 08:21:25 -0400
Subject: [PATCH] Mapper 204 support

---
 Core/Core.vcxproj         |  1 +
 Core/Core.vcxproj.filters |  3 +++
 Core/Mapper204.h          | 25 +++++++++++++++++++++++++
 Core/MapperFactory.cpp    |  4 +++-
 4 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 Core/Mapper204.h

diff --git a/Core/Core.vcxproj b/Core/Core.vcxproj
index 622bcdbd..8ef215cd 100644
--- a/Core/Core.vcxproj
+++ b/Core/Core.vcxproj
@@ -455,6 +455,7 @@
     <ClInclude Include="Mapper201.h" />
     <ClInclude Include="Mapper202.h" />
     <ClInclude Include="Mapper203.h" />
+    <ClInclude Include="Mapper204.h" />
     <ClInclude Include="Mapper212.h" />
     <ClInclude Include="Mapper213.h" />
     <ClInclude Include="Mapper214.h" />
diff --git a/Core/Core.vcxproj.filters b/Core/Core.vcxproj.filters
index 81899e6a..d8cc9f80 100644
--- a/Core/Core.vcxproj.filters
+++ b/Core/Core.vcxproj.filters
@@ -877,6 +877,9 @@
     <ClInclude Include="Mapper214.h">
       <Filter>Nes\Mappers\Unnamed</Filter>
     </ClInclude>
+    <ClInclude Include="Mapper204.h">
+      <Filter>Nes\Mappers\Unnamed</Filter>
+    </ClInclude>
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="stdafx.cpp">
diff --git a/Core/Mapper204.h b/Core/Mapper204.h
new file mode 100644
index 00000000..1a821976
--- /dev/null
+++ b/Core/Mapper204.h
@@ -0,0 +1,25 @@
+#pragma once
+#include "stdafx.h"
+#include "BaseMapper.h"
+
+class Mapper204 : public BaseMapper
+{
+protected:
+	virtual uint16_t GetPRGPageSize() { return 0x4000; }
+	virtual uint16_t GetCHRPageSize() { return 0x2000; }
+
+	void InitMapper()
+	{
+		WriteRegister(0x8000, 0);
+	}
+
+	void WriteRegister(uint16_t addr, uint8_t value)
+	{
+		uint8_t bitMask = addr & 0x06;
+		uint8_t page = bitMask + ((bitMask == 0x06) ? 0 : (addr & 0x01));
+		SelectPRGPage(0, page);
+		SelectPRGPage(1, bitMask + ((bitMask == 0x06) ? 1 : (addr & 0x01)));
+		SelectCHRPage(0, page);
+		SetMirroringType(addr & 0x10 ? MirroringType::Horizontal : MirroringType::Vertical);
+	}
+};
\ No newline at end of file
diff --git a/Core/MapperFactory.cpp b/Core/MapperFactory.cpp
index cd5fa93b..0b3a77da 100644
--- a/Core/MapperFactory.cpp
+++ b/Core/MapperFactory.cpp
@@ -60,6 +60,7 @@
 #include "Mapper201.h"
 #include "Mapper202.h"
 #include "Mapper203.h"
+#include "Mapper204.h"
 #include "Mapper212.h"
 #include "Mapper213.h"
 #include "Mapper214.h"
@@ -183,7 +184,7 @@ Supported mappers:
 |144|145|146|147|148|149|150|151|152|153|154|155|156|157|   |159|
 |   |===|   |163|164|165|166|167|168|===|170|171|172|173|===|175|
 |176|177|178|179|180|   |182|   |184|185|   |187|188|189|===|191|
-|192|193|194|195|   |197|   |   |200|201|202|203|   |205|206|207|
+|192|193|194|195|   |197|   |   |200|201|202|203|204|205|206|207|
 |   |209|210|211|212|213|214|   |   |   |218|   |   |221|222|   |
 |   |225|226|227|228|229|230|231|232|233|234|235|   |===|238|===|
 |240|241|242|243|244|245|246|===|===|249|250|===|252|   |254|   |
@@ -362,6 +363,7 @@ BaseMapper* MapperFactory::GetMapperFromID(RomData &romData)
 		case 201: return new Mapper201();
 		case 202: return new Mapper202();
 		case 203: return new Mapper203();
+		case 204: return new Mapper204();
 		case 205: return new MMC3_205();
 		case 206: return new Namco108();
 		case 207: return new TaitoX1005(true);