first tests now pass

src/mbc.cpp

@@ -1,10 +1,9 @@
 #include "addressSpace.hpp"
-#include "gameboy.hpp"
 
 void AddressSpace::determineMBCInfo() {
 	MBC = static_cast<MBCType>(memoryLayout.romBank0[0x147]);
 	romSize = 32768 * (1 << memoryLayout.romBank0[0x147]);
-	romBanks = (1 << (memoryLayout.romBank0[0x147] + 1));
+	romBanks = 1 << (memoryLayout.romBank0[0x147] + 1);
 
 	switch (memoryLayout.romBank0[0x0149]) {
 	case 0x02:
@@ -29,16 +28,90 @@ void AddressSpace::determineMBCInfo() {
 		break;
 	}
 
-	if (MBC == MBC2 || MBC2Battery) {
+	if (MBC == MBC2 || MBC == MBC2Battery) {
 		//only the lower 4 bits are usable
 		externalRamSize = 512;
 	}
 }
 
-bool GameBoy::testMBCWrite(const Byte& address) {
-	const Byte* ptr = &address;
-	if (ptr >= &addressSpace[0x0] && ptr <= &addressSpace[0x7FFF])
+bool AddressSpace::testMBCWrite(const Word address) {
+	if (address <= 0x7FFF)
 		return true;
 	return false;
 }
 
+Byte* AddressSpace::MBCRead(const Word address) {
+	if (MBC == MBC1) {
+		if (address <= 0x1FFF)
+			return &ramEnable;
+		if (address <= 0x3FFF)
+			return &romBankRegister;
+		if (address <= 0x5FFF)
+			return &twoBitBankRegister;
+		if (address <= 0x7FFF)
+			return &romRamSelect;
+	}
+	if (MBC == MBC1Ram || MBC == MBC1RamBattery) {
+		if (address <= 0x1FFF)
+			return &ramEnable;
+		//bits 0-4
+		if (address <= 0x3FFF)
+			return &romBankRegister;
+		if (address <= 0x5FFF) {
+			return &twoBitBankRegister;
+		}
+		if (address <= 0x7FFF)
+			return &romRamSelect;
+	}
+	return &dummyVal;
+}
+
+void AddressSpace::MBCUpdate() {
+	if (MBC == MBC1) {
+		//TODO: multicart roms need to be able to switch the first rom bank as well
+		//see: https://gbdev.io/pandocs/MBC1.html
+
+		//Selected ROM Bank = (Secondary Bank << 5) + ROM Bank
+		romBankRegister &= 0x1F;
+		twoBitBankRegister &= 0x3;
+
+		//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();
+	}
+	if (MBC == MBC1Ram || MBC == MBC1RamBattery) {}
+}
+
+void AddressSpace::loadRomBank() {
+	Byte* old = memoryLayout.romBankSwitch;
+	memoryLayout.romBankSwitch = game.data() + (ROM_BANK_SIZE * selectedRomBank);
+	if (old != memoryLayout.romBankSwitch)
+		printf("\n");
+}
+
+void AddressSpace::createRamBank() {
+	if (externalRamSize)
+		cartridgeRam = new Byte[externalRamSize];
+}
+
+void AddressSpace::loadRamBank() {
+	Byte* old = memoryLayout.externalRam;
+	if (cartridgeRam != nullptr)
+		memoryLayout.externalRam = cartridgeRam + (RAM_BANK_SIZE * selectedExternalRamBank);
+	if (old != memoryLayout.externalRam)
+		printf("\n");
+}
+