Saving RAM when the emulator is closed

README.md

@@ -17,11 +17,11 @@ Any help or suggestion is welcome!
   - [x] MBC1
   - [x] MBC2
   - [ ] MBC3 (partially implemented)
-  - [X] MBC5
+  - [x] MBC5
   - [ ] MBC6
   - [ ] MBC7
   - [ ] HuC1
-- [ ] Save files
+- [x] Save files
 - [ ] Web Assembly support (because this is a Rust project and it has to support Web Assembly)
 - [ ] Gameboy boot ROM (Not important for now)
 - [ ] Gameboy Color compatibility

src/bus.rs

@@ -27,8 +27,8 @@ pub const INTERRUPT_ENABLE_ADDRESS: u16 = 0xFFFF;
 pub const INTERRUPT_FLAG_ADDRESS: u16 = 0xFF0F;
 
 pub struct Bus {
-    game_rom: Box<dyn ROM>,
     data: [u8; 0x10000],
+    pub rom: Box<dyn ROM>,
     pub ppu: PPU,
     pub joypad: Joypad,
     pub timer: Timer,
@@ -39,19 +39,19 @@ impl Bus {
         let args: Vec<String> = std::env::args().collect();
         #[cfg(not(test))]
         if args.len() < 2 {
-            println!("Please, specify a ROM file");
+            eprintln!("Please, specify a ROM file");
             std::process::exit(1);
         }
-        let game_rom = match load_rom(&args.get(1).unwrap_or(&"".to_string())) {
+        let rom = match load_rom(&args.get(1).unwrap_or(&"".to_string())) {
             Ok(rom) => rom,
             Err(err) => {
-                println!("Could not read ROM: {}", err);
+                eprintln!("Could not read ROM: {}", err);
                 std::process::exit(1);
             },
         };
         let mut bus = Self {
             data: [0x00; 0x10000],
-            game_rom,
+            rom,
             ppu: PPU::new(),
             joypad: Joypad::new(),
             timer: Timer::new(),
@@ -85,7 +85,7 @@ impl Bus {
 
     pub fn read(&self, address: u16) -> u8 {
         if BANK_ZERO.contains(&address) || BANK_SWITCHABLE.contains(&address)  || EXTERNAL_RAM.contains(&address) {
-            return self.game_rom.read(address);
+            return self.rom.read(address);
         } else if address == INTERRUPT_ENABLE_ADDRESS || address == INTERRUPT_FLAG_ADDRESS {
             return 0b11100000 | self.data[address as usize];
         } else if VIDEO_RAM.contains(&address) {
@@ -112,7 +112,7 @@ impl Bus {
         }
 
         if BANK_ZERO.contains(&address) || BANK_SWITCHABLE.contains(&address) || EXTERNAL_RAM.contains(&address) {
-            self.game_rom.write(address, data);
+            self.rom.write(address, data);
         } else if WORK_RAM_1.contains(&address) || WORK_RAM_2.contains(&address) {
             self.data[address as usize] = data;
             // Copy to the ECHO RAM
@@ -120,7 +120,7 @@ impl Bus {
                 self.data[(ECHO_RAM.min().unwrap() + (address - WORK_RAM_1.min().unwrap())) as usize] = data;
             }
         } else if EXTERNAL_RAM.contains(&address) {
-            self.game_rom.write(address, data);
+            self.rom.write(address, data);
         } else if ECHO_RAM.contains(&address) {
             self.data[address as usize] = data;
             self.data[(WORK_RAM_1.min().unwrap() + (address - ECHO_RAM.min().unwrap())) as usize] = data; // Copy to the working RAM

src/emulator.rs

@@ -5,6 +5,8 @@ use winit::event::{VirtualKeyCode};
 use crate::cpu::{CPU, Cycles, Interrupt};
 use crate::bus::Bus;
 use crate::joypad::{Button};
+#[cfg(not(test))]
+use crate::rom::{save_file};
 
 pub struct Emulator {
     bus: Bus,
@@ -19,6 +21,16 @@ impl Emulator {
         }
     }
 
+    pub fn close(&self) {
+        println!("closing emulator");
+
+        #[cfg(not(test))]
+        match save_file(self.bus.rom.ram(), self.bus.rom.info()) {
+            Err(err) => eprintln!("Could not save file: {}", err),
+            _ => {},
+        };
+    }
+
     pub fn handle_input(&mut self, input: &WinitInputHelper) {
         let mut change = false;
         if input.key_pressed(VirtualKeyCode::K) {

src/lib.rs

@@ -2,6 +2,7 @@ pub mod utils;
 pub mod cpu;
 pub mod ppu;
 pub mod timer;
+pub mod sound;
 pub mod rom;
 pub mod bus;
 pub mod joypad;

src/render.rs

@@ -52,12 +52,13 @@ pub fn start_eventloop() {
     let mut pixels = create_pixels(WIDTH, HEIGHT, &window);
 
     event_loop.run(move |event, _, control_flow| {
-        *control_flow = ControlFlow::Wait;
+        // *control_flow = ControlFlow::Wait;
 
         // Handle input events
         if input.update(&event) {
             // Close events
             if input.key_pressed(VirtualKeyCode::Escape) || input.quit() {
+                emulator.close();
                 *control_flow = ControlFlow::Exit;
                 return;
             }
@@ -76,6 +77,7 @@ pub fn start_eventloop() {
                 ..
             } => {
                 println!("The close button was pressed; stopping");
+                emulator.close();
                 *control_flow = ControlFlow::Exit
             },
             Event::MainEventsCleared => {

src/rom.rs

@@ -2,6 +2,8 @@
 use std::fs::File;
 #[cfg(not(test))]
 use std::io::Read;
+#[cfg(not(test))]
+use std::io::Write;
 
 use crate::bus::{
     BANK_ZERO,
@@ -36,6 +38,7 @@ fn header_checksum(data: &Vec<u8>) -> bool {
 pub fn load_rom(_filename: &str) -> std::io::Result<Box<dyn ROM>> {
     Ok(Box::new(NoMBC::new(Vec::new(), ROMInfo {
         mbc: MBC::NoMBC,
+        filename: "".to_string(),
         publisher: "".to_string(),
         title: "".to_string(),
         cgb_only: false,
@@ -58,16 +61,59 @@ pub fn load_rom(filename: &str) -> std::io::Result<Box<dyn ROM>> {
         return Err(std::io::Error::new(std::io::ErrorKind::InvalidData, "Header checksum failed. Is this a Gameboy ROM?"));
     }
 
-    let info = ROMInfo::from_bytes(&data);
+    let mut info = ROMInfo::from_bytes(&data);
+    info.set_filename(filename.to_string());
+    let info_copy = info.clone();
 
-    Ok(match info.mbc {
+    let mut rom: Box<dyn ROM> = match info.mbc {
         MBC::NoMBC => Box::new(NoMBC::new(data, info)),
         MBC::MBC1 => Box::new(MBC1::new(data, info)),
         MBC::MBC2 => Box::new(MBC2::new(data, info)),
         MBC::MBC3 => Box::new(MBC3::new(data, info)),
         MBC::MBC5 => Box::new(MBC5::new(data, info)),
         _ => unimplemented!(),
-    })
+    };
+
+    #[cfg(not(test))]
+    match load_save(rom.ram_mut(), &info_copy) {
+        Err(err) => eprintln!("Could not load save file: {}", err),
+        _ => {},
+    };
+
+    Ok(rom)
+}
+
+#[cfg(not(test))]
+pub fn save_file(ram: &Vec<u8>, info: &ROMInfo) -> std::io::Result<()> {
+    if !info.has_ram || !info.has_battery {
+        return Ok(());
+    }
+    let mut file = File::create(format!("{}.sav", info.filename))?;
+    file.write_all(ram)?;
+    Ok(())
+}
+
+#[cfg(not(test))]
+pub fn load_save(ram: &mut Vec<u8>, info: &ROMInfo) -> std::io::Result<()> {
+    if !info.has_ram || !info.has_battery {
+        return Ok(());
+    }
+
+    let mut file = File::open(format!("{}.sav", info.filename))?;
+    let mut data = vec![];
+    file.read_to_end(&mut data)?;
+
+    let mut index = 0;
+    let size = match ram.len() < data.len() {
+        true => ram.len(),
+        false => data.len(),
+    };
+    while index < size {
+        ram[index] = data[index];
+        index += 1;
+    } 
+
+    Ok(())
 }
 
 #[derive(Debug, Copy, Clone)]
@@ -86,21 +132,22 @@ enum MBC {
     BandaiTIMA5,
 }
 
-#[derive(Debug)]
+#[derive(Copy, Clone, Debug)]
 enum Region {
     Japanese,
     NonJapanese,
 }
 
-#[derive(Debug, PartialEq)]
+#[derive(Copy, Clone, PartialEq, Debug)]
 enum BankingMode {
     Simple,
     Advanced,
 }
 
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct ROMInfo {
     mbc: MBC,
+    filename: String,
     publisher: String,
     title: String,
     cgb_only: bool,
@@ -114,6 +161,10 @@ pub struct ROMInfo {
 }
 
 impl ROMInfo {
+    pub fn set_filename(&mut self, filename: String) {
+        self.filename = filename;
+    }
+
     pub fn from_bytes(bytes: &[u8]) -> Self {
         let rom_type = bytes[CARTRIDGE_TYPE_ADDRESS as usize];
         Self {
@@ -147,6 +198,7 @@ impl ROMInfo {
                 0xFF => MBC::HuC1,
                 _ => unreachable!(),
             },
+            filename: "".to_string(),
             region: match bytes[DESTINATION_CODE_ADDRESS as usize] {
                 0x00 => Region::Japanese,
                 _ => Region::NonJapanese,
@@ -207,11 +259,15 @@ impl ROMInfo {
 pub trait ROM {
     fn read(&self, address: u16) -> u8;
     fn write(&mut self, address: u16, data: u8);
+    fn ram_mut(&mut self) -> &mut Vec<u8>;
+    fn ram(&self) -> &Vec<u8>;
+    fn info(&self) -> &ROMInfo;
 }
 
 pub struct NoMBC {
     data: Vec<u8>,
     info: ROMInfo,
+    ram: Vec<u8>,
 }
 
 impl NoMBC {
@@ -219,6 +275,7 @@ impl NoMBC {
         let rom = Self {
             data,
             info,
+            ram: Vec::new(),
         };
         println!("MBC {:?}", rom.info.mbc);
         println!("Region {:?}", rom.info.region);
@@ -236,6 +293,18 @@ impl ROM for NoMBC {
     }
 
     fn write(&mut self, _address: u16, _data: u8) {}
+
+    fn ram_mut(&mut self) -> &mut Vec<u8> {
+        &mut self.ram
+    }
+
+    fn ram(&self) -> &Vec<u8> {
+        &self.ram
+    }
+
+    fn info(&self) -> &ROMInfo {
+        &self.info
+    }
 }
 
 pub struct MBC1 {
@@ -254,6 +323,7 @@ impl MBC1 {
         println!("MBC {:?}", info.mbc);
         println!("Region {:?}", info.region);
         println!("Has RAM {}", info.has_ram);
+        println!("Has battery {}", info.has_battery);
         println!("ROM banks {}", info.rom_banks);
         println!("RAM banks {}", info.ram_banks);
         let ram = vec![0; info.ram_size() as usize];
@@ -367,6 +437,18 @@ impl ROM for MBC1 {
             }
         }
     }
+
+    fn ram_mut(&mut self) -> &mut Vec<u8> {
+        &mut self.ram
+    }
+
+    fn ram(&self) -> &Vec<u8> {
+        &self.ram
+    }
+
+    fn info(&self) -> &ROMInfo {
+        &self.info
+    }
 }
 
 pub struct MBC2 {
@@ -382,6 +464,7 @@ impl MBC2 {
         println!("MBC {:?}", info.mbc);
         println!("Region {:?}", info.region);
         println!("Has RAM {}", info.has_ram);
+        println!("Has battery {}", info.has_battery);
         println!("ROM banks {}", info.rom_banks);
         println!("RAM banks {}", info.ram_banks);
         let ram = vec![0; 0x200];
@@ -443,6 +526,18 @@ impl ROM for MBC2 {
             }
         }
     }
+
+    fn ram_mut(&mut self) -> &mut Vec<u8> {
+        &mut self.ram
+    }
+
+    fn ram(&self) -> &Vec<u8> {
+        &self.ram
+    }
+
+    fn info(&self) -> &ROMInfo {
+        &self.info
+    }
 }
 
 pub struct MBC3 {
@@ -459,6 +554,7 @@ impl MBC3 {
         println!("MBC {:?}", info.mbc);
         println!("Region {:?}", info.region);
         println!("Has RAM {}", info.has_ram);
+        println!("Has battery {}", info.has_battery);
         println!("ROM banks {}", info.rom_banks);
         println!("RAM banks {}", info.ram_banks);
         let ram = vec![0; info.ram_size() as usize];
@@ -519,6 +615,18 @@ impl ROM for MBC3 {
         }
 
     }
+
+    fn ram_mut(&mut self) -> &mut Vec<u8> {
+        &mut self.ram
+    }
+
+    fn ram(&self) -> &Vec<u8> {
+        &self.ram
+    }
+
+    fn info(&self) -> &ROMInfo {
+        &self.info
+    }
 }
 
 pub struct MBC5 {
@@ -535,6 +643,7 @@ impl MBC5 {
         println!("MBC {:?}", info.mbc);
         println!("Region {:?}", info.region);
         println!("Has RAM {}", info.has_ram);
+        println!("Has battery {}", info.has_battery);
         println!("ROM banks {}", info.rom_banks);
         println!("RAM banks {}", info.ram_banks);
         let ram = vec![0; info.ram_size() as usize];
@@ -591,4 +700,16 @@ impl ROM for MBC5 {
             }
         }
     }
+
+    fn ram_mut(&mut self) -> &mut Vec<u8> {
+        &mut self.ram
+    }
+
+    fn ram(&self) -> &Vec<u8> {
+        &self.ram
+    }
+
+    fn info(&self) -> &ROMInfo {
+        &self.info
+    }
 }

src/sound.rs

@@ -0,0 +1,47 @@
+use std::ops::RangeInclusive;
+
+pub const NR10_ADDRESS: u16 = 0xFF10;
+pub const NR11_ADDRESS: u16 = 0xFF11;
+pub const NR12_ADDRESS: u16 = 0xFF12;
+pub const NR13_ADDRESS: u16 = 0xFF13;
+pub const NR14_ADDRESS: u16 = 0xFF14;
+
+pub const NR21_ADDRESS: u16 = 0xFF16;
+pub const NR22_ADDRESS: u16 = 0xFF17;
+pub const NR23_ADDRESS: u16 = 0xFF18;
+pub const NR24_ADDRESS: u16 = 0xFF19;
+
+pub const NR30_ADDRESS: u16 = 0xFF1A;
+pub const NR31_ADDRESS: u16 = 0xFF1B;
+pub const NR32_ADDRESS: u16 = 0xFF1C;
+pub const NR33_ADDRESS: u16 = 0xFF1D;
+pub const NR34_ADDRESS: u16 = 0xFF1E;
+
+pub const NR41_ADDRESS: u16 = 0xFF20;
+pub const NR42_ADDRESS: u16 = 0xFF21;
+pub const NR43_ADDRESS: u16 = 0xFF22;
+pub const NR44_ADDRESS: u16 = 0xFF23;
+
+pub const NR50_ADDRESS: u16 = 0xFF24;
+pub const NR51_ADDRESS: u16 = 0xFF25;
+pub const NR52_ADDRESS: u16 = 0xFF26;
+
+pub const WAVE_PATTERN_RAM: RangeInclusive<u16> = 0xFF30..=0xFF3F;
+
+pub struct Sound {
+    io_registers: [u8; 48],
+}
+
+impl Sound {
+    pub fn is_io_register(address: u16) -> bool {
+        address >= 0xFF10 && address <= 0xFF3F
+    }
+
+    pub fn get_register(&self, address: u16) -> u8 {
+        self.io_registers[(address - 0xFF10) as usize]
+    }
+
+    pub fn set_register(&mut self, address: u16, data: u8) {
+        self.io_registers[(address - 0xFF10) as usize] = data;
+    }
+}