chore(cartridge): impelement MBC3

This commit is contained in:
Rekai Nyangadzayi Musuka 2021-06-10 16:57:40 -05:00
parent 482d226cd6
commit 0c22509d24
1 changed files with 105 additions and 6 deletions

View File

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