GB: MBC3: correct behavior when bank value of 0 is written. thanks to sanqui for pointing this out

libgambatte/libgambatte.vcxproj

@@ -57,6 +57,9 @@
       <SubSystem>Windows</SubSystem>
       <GenerateDebugInformation>true</GenerateDebugInformation>
     </Link>
+    <PostBuildEvent>
+      <Command>copy /y $(TargetDir)$(TargetFileName) $(ProjectDir)..\output\dll\$(TargetFileName)</Command>
+    </PostBuildEvent>
   </ItemDefinitionGroup>
   <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
     <ClCompile>
@@ -76,6 +79,9 @@
       <EnableCOMDATFolding>true</EnableCOMDATFolding>
       <OptimizeReferences>true</OptimizeReferences>
     </Link>
+    <PostBuildEvent>
+      <Command>copy /y $(TargetDir)$(TargetFileName) $(ProjectDir)..\output\dll\$(TargetFileName)</Command>
+    </PostBuildEvent>
   </ItemDefinitionGroup>
   <ItemGroup>
     <ClInclude Include="include\gambatte.h" />

libgambatte/src/mem/cartridge.cpp

@@ -254,6 +254,7 @@ class Mbc3 : public DefaultMbc {
 	unsigned char rambank;
 	bool enableRam;
 
+	static unsigned adjustedRombank(unsigned bank) { return bank & 0x7F ? bank : bank | 1; }
 	void setRambank() const {
 		unsigned flags = enableRam ? MemPtrs::READ_EN | MemPtrs::WRITE_EN : 0;
 		
@@ -266,6 +267,9 @@ class Mbc3 : public DefaultMbc {
 
 		memptrs.setRambank(flags, rambank & (rambanks(memptrs) - 1));
 	}
+	// we adjust the rombank before masking with size?  this seems correct, as how would the mbc
+	// know that high rom address outputs were not connected
+	void setRombank() const { memptrs.setRombank(adjustedRombank(rombank) & (rombanks(memptrs) - 1)); }
 
 public:
 	Mbc3(MemPtrs &memptrs, Rtc *const rtc)
@@ -285,7 +289,7 @@ public:
 			break;
 		case 1:
 			rombank = data & 0x7F;
-			memptrs.setRombank(rombank & (rombanks(memptrs) - 1));
+			setRombank();
 			break;
 		case 2:
 			rambank = data;
@@ -310,7 +314,7 @@ public:
 		rambank = ss.rambank;
 		enableRam = ss.enableRam;
 		setRambank();
-		memptrs.setRombank(rombank & (rombanks(memptrs) - 1));
+		setRombank();
 	}
 };