From ae3e6c4978559b41fbc0bc088219dbbdea09420a Mon Sep 17 00:00:00 2001
From: Souryo <mesenemu@gmail.com>
Date: Wed, 30 Dec 2015 19:41:01 -0500
Subject: [PATCH] CNROM w/ copy protection (Mapper 185) support

---
 Core/BaseMapper.h      | 12 +++++++++++-
 Core/CNROM.h           | 38 ++++++++++++++++++++++++++++----------
 Core/MapperFactory.cpp |  3 ++-
 3 files changed, 41 insertions(+), 12 deletions(-)

diff --git a/Core/BaseMapper.h b/Core/BaseMapper.h
index 67d04b46..d2259c39 100644
--- a/Core/BaseMapper.h
+++ b/Core/BaseMapper.h
@@ -143,6 +143,7 @@ class BaseMapper : public IMemoryHandler, public Snapshotable, public INotificat
 			for(uint16_t i = startAddr; i <= endAddr; i++) {
 				_prgPages[i] = source;
 				_prgPageAccessType[i] = accessType != -1 ? accessType : defaultAccessType;
+
 				source += 0x100;
 			}
 		}
@@ -166,10 +167,19 @@ class BaseMapper : public IMemoryHandler, public Snapshotable, public INotificat
 			for(uint16_t i = startAddr; i <= endAddr; i++) {
 				_chrPages[i] = sourceMemory;
 				_chrPageAccessType[i] = accessType != -1 ? accessType : MemoryAccessType::ReadWrite;
-				sourceMemory += 0x100;
+
+				if(sourceMemory != nullptr) {
+					sourceMemory += 0x100;
+				}
 			}
 		}
 
+		void RemovePpuMemoryMapping(uint16_t startAddr, uint16_t endAddr)
+		{
+			//Unmap this section of memory (causing open bus behavior)
+			SetPpuMemoryMapping(startAddr, endAddr, nullptr, MemoryAccessType::NoAccess);
+		}
+
 		uint8_t InternalReadRam(uint16_t addr)
 		{
 			return _prgPages[addr >> 8] ? _prgPages[addr >> 8][addr & 0xFF] : 0;
diff --git a/Core/CNROM.h b/Core/CNROM.h
index ea9b08b0..a828faac 100644
--- a/Core/CNROM.h
+++ b/Core/CNROM.h
@@ -4,18 +4,36 @@
 
 class CNROM : public BaseMapper
 {
-	protected:
-		virtual uint16_t GetPRGPageSize() { return 0x8000; }
-		virtual uint16_t GetCHRPageSize() {	return 0x2000; }
+private:
+	bool _enableCopyProtection;
 
-		void InitMapper() 
-		{
-			SelectPRGPage(0, 0);
-			SelectCHRPage(0, 0);
-		}
+protected:
+	virtual uint16_t GetPRGPageSize() { return 0x8000; }
+	virtual uint16_t GetCHRPageSize() { return 0x2000; }
 
-		void WriteRegister(uint16_t addr, uint8_t value)
-		{
+	void InitMapper()
+	{
+		SelectPRGPage(0, 0);
+		SelectCHRPage(0, 0);
+	}
+
+	void WriteRegister(uint16_t addr, uint8_t value)
+	{
+		if(_enableCopyProtection) {
+			//"if C AND $0F is nonzero, and if C does not equal $13: CHR is enabled"
+			//This means Seicross (mapper 185 version) will not work (to allow Spy vs Spy (J) to work
+			if((value & 0x0F) != 0 && value != 0x13) {
+				SelectCHRPage(0, 0);
+			} else {
+				RemovePpuMemoryMapping(0x0000, 0x1FFF);
+			}
+		} else {
 			SelectCHRPage(0, value);
 		}
+	}
+
+public:
+	CNROM(bool enableCopyProtection) : _enableCopyProtection(enableCopyProtection)
+	{
+	}
 };
\ No newline at end of file
diff --git a/Core/MapperFactory.cpp b/Core/MapperFactory.cpp
index 0b9f2db8..cb266d4d 100644
--- a/Core/MapperFactory.cpp
+++ b/Core/MapperFactory.cpp
@@ -37,7 +37,7 @@ BaseMapper* MapperFactory::GetMapperFromID(uint8_t mapperID)
 		case 0: return new NROM();
 		case 1: return new MMC1();
 		case 2: return new UNROM();
-		case 3: return new CNROM();
+		case 3: return new CNROM(false);
 		case 4: return new MMC3();
 		case 5: return new MMC5();
 		case 7: return new AXROM();
@@ -67,6 +67,7 @@ BaseMapper* MapperFactory::GetMapperFromID(uint8_t mapperID)
 		case 101: return new JalecoJfxx(true);
 		case 152: return new Bandai74161_7432(true);
 		case 163: return new Nanjing();
+		case 185: return new CNROM(true);
 		case 189: return new MMC3_189();
 	}