use super::cartridge::Cartridge; use super::high_ram::HighRam; use super::instruction::Cycles; use super::interrupt::Interrupt; use super::ppu::Ppu; use super::serial::Serial; use super::sound::Sound; use super::timer::Timer; use super::work_ram::{VariableWorkRam, WorkRam}; use std::{convert::TryInto, fs::File, io::Read}; #[derive(Debug, Clone)] pub struct Bus { boot: Option<[u8; 256]>, // Boot ROM is 256b long cartridge: Option, pub ppu: Ppu, wram: WorkRam, vwram: VariableWorkRam, timer: Timer, interrupt: Interrupt, sound: Sound, hram: HighRam, serial: Serial, } impl Default for Bus { fn default() -> Self { Self { boot: None, cartridge: None, ppu: Default::default(), wram: Default::default(), vwram: Default::default(), timer: Default::default(), interrupt: Default::default(), sound: Default::default(), hram: Default::default(), serial: Default::default(), } } } impl Bus { pub fn with_boot(path: &str) -> Self { let mut file = File::open(path).unwrap(); let mut buf = Vec::with_capacity(256); file.read_to_end(&mut buf).unwrap(); let boot_rom: [u8; 256] = buf.try_into().unwrap(); Self { boot: Some(boot_rom), ..Default::default() } } pub fn load_cartridge(&mut self, path: &str) { self.cartridge = Some(Cartridge::new(path).unwrap()); } pub fn step(&mut self, cycles: Cycles) { let _ = self.timer.step(cycles); let _ = self.sound.step(cycles); let _ = self.ppu.step(cycles); } } impl Bus { pub fn read_byte(&self, addr: u16) -> u8 { match addr { 0x0000..=0x3FFF => { // 16KB ROM bank 00 if addr < 0x00FF { if let Some(boot) = self.boot { return boot[addr as usize]; } } match self.cartridge.as_ref() { Some(cart) => cart.read_byte(addr), None => panic!("Tried to read from a non-existant cartridge"), } } 0x4000..=0x7FFF => match self.cartridge.as_ref() { // 16KB ROM Bank 01 -> NN (switchable via MB) Some(cart) => cart.read_byte(addr), None => panic!("Tried to read from a non-existant cartridge"), }, 0x8000..=0x9FFF => { // 8KB Video RAM self.ppu.vram[(addr - 0x8000) as usize] } 0xA000..=0xBFFF => match self.cartridge.as_ref() { // 8KB External RAM Some(cart) => cart.read_byte(addr), None => panic!("Tried to read from the external RAM of a non-existant cartridge"), }, 0xC000..=0xCFFF => { // 4KB Work RAM Bank 0 self.wram.read_byte((addr - 0xC000) as usize) } 0xD000..=0xDFFF => { // 4KB Work RAM Bank 1 -> N self.vwram.read_byte((addr - 0xD000) as usize) } 0xE000..=0xFDFF => { // Mirror of 0xC000 to 0xDDFF unimplemented!("Unable to read {:#06X} in Restricted Mirror", addr); } 0xFE00..=0xFE9F => { // Sprite Attribute Table unimplemented!("Unable to read {:#06X} in the Sprite Attribute Table", addr); } 0xFEA0..=0xFEFF => unimplemented!("{:#06X} is not allowed to be used", addr), 0xFF00..=0xFF7F => { // IO Registers match addr { 0xFF01 => self.serial.next, 0xFF02 => self.serial.control.into(), 0xFF07 => self.timer.control.into(), 0xFF0F => self.interrupt.flag.into(), 0xFF11 => self.sound.ch1.sound_duty.into(), 0xFF12 => self.sound.ch1.vol_envelope.into(), 0xFF14 => self.sound.ch1.freq_hi.into(), 0xFF24 => self.sound.control.channel.into(), 0xFF25 => self.sound.control.output.into(), 0xFF26 => self.sound.control.status.into(), 0xFF40 => self.ppu.lcd_control.into(), 0xFF41 => self.ppu.stat.into(), 0xFF42 => self.ppu.pos.scroll_y, 0xFF43 => self.ppu.pos.scroll_x, 0xFF44 => self.ppu.pos.line_y, 0xFF47 => self.ppu.monochrome.bg_palette.into(), _ => unimplemented!("Unable to read {:#06X} in I/O Registers", addr), } } 0xFF80..=0xFFFE => { // High RAM self.hram.read_byte((addr - 0xFF80) as usize) } 0xFFFF => { // Interrupts Enable Register self.interrupt.enable.into() } } } pub fn write_byte(&mut self, addr: u16, byte: u8) { match addr { 0x0000..=0x3FFF => { // 16KB ROM bank 00 match self.cartridge.as_mut() { Some(cart) => cart.write_byte(addr, byte), None => panic!("Tried to write into non-existent Cartridge"), } } 0x4000..=0x7FFF => { // 16KB ROM Bank 01 -> NN (switchable via MB) match self.cartridge.as_mut() { Some(cart) => cart.write_byte(addr, byte), None => panic!("Tried to write into non-existent Cartridge"), } } 0x8000..=0x9FFF => { // 8KB Video RAM self.ppu.vram[(addr - 0x8000) as usize] = byte; } 0xA000..=0xBFFF => { // 8KB External RAM match self.cartridge.as_mut() { Some(cart) => cart.write_byte(addr, byte), None => panic!("Tried to write into non-existent Cartridge"), } } 0xC000..=0xCFFF => { // 4KB Work RAM Bank 0 self.wram.write_byte((addr - 0xC000) as usize, byte); } 0xD000..=0xDFFF => { // 4KB Work RAM Bank 1 -> N self.vwram.write_byte((addr - 0xD000) as usize, byte); } 0xE000..=0xFDFF => { // Mirror of 0xC000 to 0xDDFF unimplemented!("Unable to write to {:#06X} in Restricted Mirror", addr); } 0xFE00..=0xFE9F => { // Sprite Attribute Table unimplemented!( "Unable to write to {:#06X} in the Sprite Attribute Table", addr ); } 0xFEA0..=0xFEFF => unimplemented!("{:#06X} is not allowed to be used", addr), 0xFF00..=0xFF7F => { // IO Registers match addr { 0xFF01 => self.serial.next = byte, 0xFF02 => self.serial.control = byte.into(), 0xFF07 => self.timer.control = byte.into(), 0xFF0F => self.interrupt.flag = byte.into(), 0xFF11 => self.sound.ch1.sound_duty = byte.into(), 0xFF12 => self.sound.ch1.vol_envelope = byte.into(), 0xFF13 => self.sound.ch1.freq_lo = byte.into(), 0xFF14 => self.sound.ch1.freq_hi = byte.into(), 0xFF24 => self.sound.control.channel = byte.into(), 0xFF25 => self.sound.control.output = byte.into(), 0xFF26 => self.sound.control.status = byte.into(), // FIXME: Should we control which bytes are written to here? 0xFF40 => self.ppu.lcd_control = byte.into(), 0xFF41 => self.ppu.stat = byte.into(), 0xFF42 => self.ppu.pos.scroll_y = byte, 0xFF43 => self.ppu.pos.scroll_x = byte, 0xFF44 => self.ppu.pos.line_y = byte, 0xFF47 => self.ppu.monochrome.bg_palette = byte.into(), 0xFF50 => { // Disable Boot ROM if byte != 0 { self.boot = None; } } _ => unimplemented!("Unable to write to {:#06X} in I/O Registers", addr), }; } 0xFF80..=0xFFFE => { // High RAM self.hram.write_byte((addr - 0xFF80) as usize, byte); } 0xFFFF => { // Interrupts Enable Register self.interrupt.enable = byte.into(); } } } pub fn read_word(&self, addr: u16) -> u16 { (self.read_byte(addr + 1) as u16) << 8 | self.read_byte(addr) as u16 } pub fn write_word(&mut self, addr: u16, word: u16) { self.write_byte(addr + 1, (word >> 8) as u8); self.write_byte(addr, (word & 0x00FF) as u8); } }