more MBC3 work

CMakeLists.txt

@@ -19,7 +19,11 @@ add_executable(GameBoy++ src/main.cpp
         src/testing.hpp
         src/joypad.cpp
 )
+target_compile_options(GameBoy++ PRIVATE -O2)
 target_link_libraries(GameBoy++ ${SDL2_LIBRARIES})
+target_compile_options(GameBoy++ PRIVATE
+    $<$<CONFIG:Release>:-O2>
+)
 
 if(CMAKE_EXPORT_COMPILE_COMMANDS)
   add_custom_target(copy_compile_commands ALL

src/addressSpace.hpp

@@ -93,8 +93,7 @@ public:
   void loadGame(const std::string &filename);
 
   void determineMBCInfo();
-  bool MBCWrite(Word address);
-  Byte *MBCRead(Word address);
+  Byte *MBCWrite(Word address);
   // prevents seg faults when programs with no MBC try to write to ROM
   Byte dummyVal = 0;
 
@@ -114,10 +113,10 @@ public:
   void dmaTransfer();
 
   // MBC registers
-  // Selected ROM Bank = (Secondary Bank << 5) + ROM Bank
+  // Selected ROM Bank in MBC1 = (Secondary Bank << 5) + ROM Bank
   Byte selectedRomBank = 0;
   Byte romBankRegister = 0x00;
-  // 2 bit register acts as secondary rom bank register or ram bank number
+  // 2 bit register acts as secondary rom bank register or ram bank number in MBC1
   Byte twoBitBankRegister = 0x0;
   Byte selectedExternalRamBank = 0;
   Byte romRamSelect = 0x00;
@@ -138,34 +137,33 @@ public:
       return testRam[address];
     if (address < 0x0100 && bootromLoaded)
       return bootrom[address];
-    if (address < 0x4000)
+    else if (address < 0x4000)
       return memoryLayout.romBank0[address];
-    if (address < 0x8000)
+    else if (address < 0x8000)
       return memoryLayout.romBankSwitch[address - 0x4000];
-    if (address < 0xA000)
+    else if (address < 0xA000)
       return memoryLayout.vram[address - 0x8000];
-    if (address < 0xC000) {
+    else if (address < 0xC000) {
       if (externalRamSize == 0)
         return 0xFF;
       // MBC2 echos 15 times and only stores lower 4 bits
-      if (MBC == MBC2 || MBC == MBC2Battery)
+      else if (MBC == MBC2 || MBC == MBC2Battery)
         return memoryLayout.externalRam[(address - 0xA000) & 0x01FF] | 0xF0;
+      else
         return memoryLayout.externalRam[address - 0xA000];
-    }
-    if (address < 0xD000)
+    } else if (address < 0xD000)
       return memoryLayout.memoryBank1[address - 0xC000];
-    if (address < 0xE000)
+    else if (address < 0xE000)
       return memoryLayout.memoryBank2[address - 0xD000];
-    if (address < 0xFE00)
+    else if (address < 0xFE00)
       return memoryLayout.memoryBank1[address - 0xE000];
-    if (address < 0xFEA0)
+    else if (address < 0xFEA0)
       return memoryLayout.oam[address - 0xFE00];
-    if (address < 0xFF00) {
+    else if (address < 0xFF00) {
       if ((memoryLayout.STAT & 0x03) == 2 || (memoryLayout.STAT & 0x03) == 3)
         return 0xFF;
       return 0x00;
-    }
-    if (address < 0xFF80)
+    } else if (address < 0xFF80)
       switch (address) {
       case 0xFF00:
         return memoryLayout.JOYP;
@@ -235,8 +233,6 @@ public:
       case 0xFF43:
         return memoryLayout.SCX;
       case 0xFF44:
-        // for debugging only
-        // return 0x90;
         return memoryLayout.LY;
       case 0xFF45:
         return memoryLayout.LYC;
@@ -258,7 +254,7 @@ public:
         }
         return 0xFF;
       }
-    if (address < 0xFFFF)
+    else if (address < 0xFFFF)
       return memoryLayout.specialRam[address - 0xFF80];
     // 0xFFFF
     return memoryLayout.IE;
@@ -269,28 +265,27 @@ public:
     dummyVal = 0xFF;
     if (testing)
       return testRam[address];
-    if (address < 0x0100 && bootromLoaded)
+    else if (address < 0x0100 && bootromLoaded)
       return bootrom[address];
-    if (address < 0x8000)
-      return (*MBCRead(address));
-    if (address < 0xA000)
+    else if (address < 0x8000)
+      return (*MBCWrite(address));
+    else if (address < 0xA000)
       return memoryLayout.vram[address - 0x8000];
-    if (address < 0xC000) {
+    else if (address < 0xC000) {
       if (externalRamSize == 0)
         return dummyVal;
       return memoryLayout.externalRam[address - 0xA000];
-    }
-    if (address < 0xD000)
+    } else if (address < 0xD000)
       return memoryLayout.memoryBank1[address - 0xC000];
-    if (address < 0xE000)
+    else if (address < 0xE000)
       return memoryLayout.memoryBank2[address - 0xD000];
-    if (address < 0xFE00)
+    else if (address < 0xFE00)
       return memoryLayout.memoryBank1[address - 0xE000];
-    if (address < 0xFEA0)
+    else if (address < 0xFEA0)
       return memoryLayout.oam[address - 0xFE00];
-    if (address < 0xFF00)
+    else if (address < 0xFF00)
       return memoryLayout.notUsable[address - 0xFEA0];
-    if (address < 0xFF80)
+    else if (address < 0xFF80)
       switch (address) {
       case 0xFF00:
         return memoryLayout.JOYP;
@@ -384,7 +379,7 @@ public:
         }
         return dummyVal;
       }
-    if (address < 0xFFFF)
+    else if (address < 0xFFFF)
       return memoryLayout.specialRam[address - 0xFF80];
     // 0xFFFF
     return memoryLayout.IE;

src/mbc.cpp

@@ -35,13 +35,7 @@ void AddressSpace::determineMBCInfo() {
   }
 }
 
-bool AddressSpace::MBCWrite(const Word address) {
-  if (address <= 0x7FFF)
-    return true;
-  return false;
-}
-
-Byte *AddressSpace::MBCRead(const Word address) {
+Byte *AddressSpace::MBCWrite(const Word address) {
   if (MBC == MBC1) {
     if (address <= 0x1FFF)
       return &ramEnable;
@@ -70,8 +64,16 @@ Byte *AddressSpace::MBCRead(const Word address) {
         return &ramEnable;
     }
   } else if (MBC == MBC3 || MBC == MBC3TimerBattery) {
+    if (address <= 0x1FFF)
+      return &ramEnable;
   } else if (MBC == MBC3Ram || MBC == MBC3RamBattery ||
              MBC == MBC3TimerRamBattery) {
+    if (address <= 0x1FFF)
+      return &ramEnable;
+    if (address <= 0x3FFF)
+      return &romBankRegister;
+    if (address <= 0x5FFF)
+      return &ramBankRTCRegister;
   }
   return &dummyVal;
 }
@@ -131,38 +133,16 @@ void AddressSpace::MBCUpdate() {
     loadRomBank();
     loadRamBank();
   } else if (MBC == MBC3 || MBC == MBC3TimerBattery) {
-    romBankRegister &= 0b11111;
-    twoBitBankRegister &= 0b11;
+    selectedRomBank = romBankRegister & 0x7F;
 
-    // 512 KiB can only have 8KiB of ram
-    if (romSize >= 524288) {
-      if (romBankRegister == 0)
-        selectedRomBank = (twoBitBankRegister << 5) + 1;
-      selectedRomBank = (twoBitBankRegister << 5) + romBankRegister;
-    } else {
-      if (romBankRegister == 0)
-        selectedRomBank = 1;
-      else
-        selectedRomBank = romBankRegister;
-    }
+    loadRomBank();
+    loadRamBank();
   } else if (MBC == MBC3Ram || MBC == MBC3RamBattery ||
              MBC == MBC3TimerRamBattery) {
-    romBankRegister &= 0b11111;
-    twoBitBankRegister &= 0b11;
+    selectedRomBank = romBankRegister & 0x7F;
 
-    // 512 KiB can only have 8KiB of ram
-    if (romSize >= 524288) {
-      if (romBankRegister == 0)
-        selectedRomBank = (twoBitBankRegister << 5) + 1;
-      selectedRomBank = (twoBitBankRegister << 5) + romBankRegister;
-      selectedExternalRamBank = 0;
-    } else {
-      if (romBankRegister == 0)
-        selectedRomBank = 1;
-      else
-        selectedRomBank = romBankRegister;
-      selectedExternalRamBank = twoBitBankRegister;
-    }
+    loadRomBank();
+    loadRamBank();
   }
 }