chore(cartridge): impelement MBC3
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parent
482d226cd6
commit
0c22509d24
111
src/cartridge.rs
111
src/cartridge.rs
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@ -46,6 +46,25 @@ impl Cartridge {
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Box::new(mbc)
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}
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MbcKind::Mbc3WithBattery => {
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// TODO: Implement Saving
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let mbc = MBC3 {
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ram_size,
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ram: vec![0; ram_byte_count as usize],
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..Default::default()
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};
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Box::new(mbc)
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}
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MbcKind::Mbc3 => {
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let mbc = MBC3 {
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ram_size,
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ram: vec![0; ram_byte_count as usize],
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..Default::default()
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};
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Box::new(mbc)
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}
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MbcKind::Mbc5 => todo!("Implement MBC5"),
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}
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}
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@ -83,6 +102,8 @@ impl Cartridge {
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0x00 => MbcKind::None,
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0x01 => MbcKind::Mbc1,
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0x19 => MbcKind::Mbc5,
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0x13 => MbcKind::Mbc3WithBattery,
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0x11 => MbcKind::Mbc3,
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_ => unimplemented!("id {:#04X} is an unsupported MBC", id),
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}
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}
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@ -93,7 +114,7 @@ impl BusIo for Cartridge {
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use MbcResult::*;
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match self.mbc.handle_read(addr) {
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Address(addr) => self.memory[addr as usize],
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Address(addr) => self.memory[addr],
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Value(byte) => byte,
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}
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}
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@ -189,14 +210,14 @@ impl MemoryBankController for Mbc1 {
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0x0000..=0x3FFF => {
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if self.mode {
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let zero_bank = self.calc_zero_bank_number() as u16;
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Address(0x4000 * zero_bank + addr)
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Address(0x4000 * zero_bank as usize + addr as usize)
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} else {
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Address(addr)
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Address(addr as usize)
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}
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}
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0x4000..=0x7FFF => {
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let high_bank = self.calc_high_bank_number() as u16;
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Address(0x4000 * high_bank + (addr - 0x4000))
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Address(0x4000 * high_bank as usize + (addr as usize - 0x4000))
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}
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0xA000..=0xBFFF => {
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if self.ram_enabled {
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@ -228,12 +249,87 @@ impl MemoryBankController for Mbc1 {
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}
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}
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}
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#[derive(Debug, Clone, Copy)]
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enum MBC3Device {
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ExternalRam,
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RealTimeClock,
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}
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#[derive(Debug, Clone, Default)]
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struct MBC3 {
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/// 7-bit Number
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rom_bank: u8,
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/// 2-bit Number
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ram_bank: u8,
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devices_enabled: bool,
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currently_mapped: Option<MBC3Device>,
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ram_size: RamSize,
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ram: Vec<u8>,
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}
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impl MemoryBankController for MBC3 {
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fn handle_read(&self, addr: u16) -> MbcResult {
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use MbcResult::*;
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let res = match addr {
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0x0000..=0x3FFF => Address(addr as usize),
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0x4000..=0x7FFF => Address(0x4000 * self.rom_bank as usize + (addr as usize - 0x4000)),
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0xA000..=0xBFFF => match self.currently_mapped {
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Some(MBC3Device::ExternalRam) if self.devices_enabled => {
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Value(self.ram[0x2000 * self.ram_bank as usize + (addr as usize - 0xA000)])
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}
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Some(MBC3Device::RealTimeClock) if self.devices_enabled => {
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unimplemented!("Reading from MBC3 RTC is currently unsupported")
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}
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_ => Value(0xFF),
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},
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_ => unreachable!("A read from {:#06X} should not be handled by MBC3", addr),
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};
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res
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}
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fn handle_write(&mut self, addr: u16, byte: u8) {
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match addr {
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0x000..=0x1FFF => self.devices_enabled = (byte & 0x0F) == 0x0A, // Enable External RAM and Access to RTC if there is one
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0x2000..=0x3FFF => match byte {
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0x00 => self.rom_bank = 0x01,
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byte => self.rom_bank = byte & 0x7F,
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},
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0x4000..=0x5FFF => match byte {
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0x00 | 0x01 | 0x02 | 0x03 => {
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self.ram_bank = byte & 0x03;
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self.currently_mapped = Some(MBC3Device::ExternalRam);
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}
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0x08 | 0x09 | 0x0A | 0x0B | 0x0C => {
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self.currently_mapped = Some(MBC3Device::RealTimeClock);
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unimplemented!("RTC in MBC3 is currently unimplemented")
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}
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_ => {}
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},
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0x6000..=0x7FFF => unimplemented!("RTC Data Latch is currently unimplemented"),
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0xA000..=0xBFFF => match self.currently_mapped {
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Some(MBC3Device::ExternalRam) if self.devices_enabled => {
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self.ram[0x2000 * self.ram_bank as usize + (addr as usize - 0xA000)] = byte
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}
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Some(MBC3Device::RealTimeClock) if self.devices_enabled => {
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unimplemented!("Writing to MBC3 RTC is currently unsupported")
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}
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_ => {}
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},
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_ => unreachable!("A write to {:#06X} should not be handled by MBC3", addr),
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}
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}
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}
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#[derive(Debug, Clone, Copy)]
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struct NoMbc {}
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impl MemoryBankController for NoMbc {
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fn handle_read(&self, addr: u16) -> MbcResult {
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MbcResult::Address(addr)
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MbcResult::Address(addr as usize)
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}
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fn handle_write(&mut self, _addr: u16, _byte: u8) {
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@ -259,8 +355,9 @@ where
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}
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}
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#[derive(Debug, Clone, Copy)]
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enum MbcResult {
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Address(u16),
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Address(usize),
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Value(u8),
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}
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@ -269,6 +366,8 @@ enum MbcKind {
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None,
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Mbc1,
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Mbc5,
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Mbc3WithBattery,
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Mbc3,
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}
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impl Default for MbcKind {
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