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4 changed files with 95 additions and 122 deletions

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@ -7,23 +7,12 @@ Any help or suggestion is welcome!
## TODO
- [x] CPU implementation
- [x] Interrupts
- [x] Interrupts (interrupts test not passing yet)
- [x] Timer
- [x] Joypad (not configurable yet)
- [X] PPU implementations
- [ ] PPU implementations
- [ ] Gameboy boot ROM
- [x] Render the pixels
- [ ] MBC Implementations
- [x] NoMBC
- [ ] MBC1
- [ ] MBC2
- [ ] MBC3
- [ ] MBC4
- [ ] MBC5
- [ ] MBC6
- [ ] MBC7
- [ ] HuC1
- [ ] 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
- [ ] Sound
- [ ] Many code refactors and optimizations are needed
- [ ] Web Assembly support (because this is a Rust project and it has to support Web Assembly)

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@ -57,7 +57,7 @@ pub struct Bus {
impl Bus {
pub fn new() -> Self {
let game_rom = match ROM::load_file("ignore/dmg-acid2.gb".to_string()) {
let game_rom = match ROM::load_file("ignore/tetris.gb".to_string()) {
// let game_rom = match ROM::load_file("ignore/mooneye/emulator-only/mbc1/bits_bank1.gb".to_string()) {
// let game_rom = match ROM::load_file("roms/cpu_instrs.gb".to_string()) {
// let game_rom = match ROM::load_file("roms/cpu_instrs_individual/01-special.gb".to_string()) {
@ -129,6 +129,7 @@ impl Bus {
if BANK_ZERO.in_range(address) || BANK_SWITCHABLE.in_range(address) || EXTERNAL_RAM.in_range(address) {
self.game_rom.write(address, data);
// println!("WRITING TO ROM");
} else if WORK_RAM_1.in_range(address) || WORK_RAM_2.in_range(address) {
self.data[address as usize] = data;
// Copy to the ECHO RAM
@ -142,12 +143,9 @@ impl Bus {
self.data[(WORK_RAM_1.begin() + (address - ECHO_RAM.begin())) as usize] = data; // Copy to the working RAM
} else if address == TIMER_DIVIDER_REGISTER_ADDRESS {
self.reset_timer = true;
} else if address == LCD_CONTROL_ADDRESS {
} else if address == LCD_CONTROL_ADDRESS && get_bit(data, BitIndex::I7) {
self.data[address as usize] = data;
// Check if LCD is being turned on
if get_bit(data, BitIndex::I7) && !get_bit(self.data[address as usize], BitIndex::I7) {
self.data[LCD_Y_ADDRESS as usize] = 0x00;
}
} else if address == LCD_Y_ADDRESS {
// println!("Write to LCD_Y not allowed");
} else if address == LCD_STATUS_ADDRESS {

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@ -23,8 +23,8 @@ pub const DMA_ADDRESS: u16 = 0xFF46;
pub const BACKGROUND_PALETTE_ADDRESS: u16 = 0xFF47;
pub const OBJECT_PALETTE_0_ADDRESS: u16 = 0xFF48;
pub const OBJECT_PALETTE_1_ADDRESS: u16 = 0xFF49;
pub const WINDOW_X_ADDRESS: u16 = 0xFF4B;
pub const WINDOW_Y_ADDRESS: u16 = 0xFF4A;
pub const WINDOW_X_ADDRESS: u16 = 0xFF4A;
pub const WINDOW_Y_ADDRESS: u16 = 0xFF4B;
pub const TILE_MAP_ADDRESS: u16 = 0x9800;
#[derive(Debug, Copy, Clone)]
@ -89,6 +89,12 @@ pub enum LCDStatus {
ModeFlag(LCDStatusModeFlag),
}
pub struct PPU {
prev_state: bool,
cycles: Cycles,
sprite_buffer: Vec<Sprite>,
}
struct Sprite {
x: u8,
y: u8,
@ -105,13 +111,13 @@ impl Sprite {
self.x
}
pub fn get_pixel(&self, lcd_x: u8, lcd_y: u8, bus: &Bus, last_bg_index: u8) -> Option<Pixel> {
pub fn get_pixel(&self, lcd_x: u8, lcd_y: u8, bus: &Bus) -> Option<Pixel> {
if lcd_x < self.x.saturating_sub(8) || lcd_x >= self.x {
return None;
}
if self.over_bg && (last_bg_index & 0b11) != 0 {
return None;
if self.over_bg {
// todo!("Implement over_bg sprite property");
}
let height: u8 = match self.is_long {
@ -145,11 +151,9 @@ impl Sprite {
let tile_byte_1 = bus.read(addr);
let tile_byte_2 = bus.read(addr + 1);
let pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2);
let pixel_index = (x as usize).rem_euclid(8);
let index = (x as usize).rem_euclid(8);
if pixels[index] == 0 {
if PPU::get_two_bit_byte_pixels(tile_byte_1, tile_byte_2)[pixel_index] == 0 {
return None;
}
@ -157,26 +161,19 @@ impl Sprite {
true => bus.read(OBJECT_PALETTE_1_ADDRESS),
false => bus.read(OBJECT_PALETTE_0_ADDRESS),
};
Some(PPU::get_pixel(PPU::get_palette(pixels[index], palette)))
}
}
let pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2, palette);
pub struct PPU {
state: bool,
cycles: Cycles,
sprite_buffer: Vec<Sprite>,
window_y_counter: u8,
last_bg_index: u8,
Some(pixels[pixel_index])
}
}
impl PPU {
pub fn new() -> Self {
Self {
state: false,
prev_state: false,
cycles: Cycles(0),
sprite_buffer: Vec::new(),
window_y_counter: 0,
last_bg_index: 0,
}
}
@ -202,8 +199,8 @@ impl PPU {
self.oam_search(bus);
} else if self.cycles.0 > 80 && self.cycles.0 <= 80 + 172 && !PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD)) {
// Mode 3 drawing pixel line. This could also last 289 cycles
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD), true);
self.draw_line(bus, frame_buffer);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD), true);
} else if self.cycles.0 > 80 + 172 && self.cycles.0 <= 80 + 172 + 204 && !PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::HBlank)) {
// Mode 0 Horizontal blank. This could last 87 or 204 cycles depending on the mode 3
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::HBlank), true);
@ -211,8 +208,8 @@ impl PPU {
}
} else if PPU::get_lcd_y(bus) >= 144 && !PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::VBlank)) {
// Mode 1 Vertical blank
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::VBlank), true);
bus.set_interrupt_flag(Interrupt::VBlank, true);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::VBlank), true);
self.stat_interrupt(bus);
}
@ -223,47 +220,30 @@ impl PPU {
self.reset_cycles();
PPU::set_lcd_y(bus, PPU::get_lcd_y(bus).wrapping_add(1));
// Frame completed
if PPU::get_lcd_y(bus) > 153 {
PPU::set_lcd_y(bus, 0);
self.window_y_counter = 0;
}
// self.check_lyc(bus);
self.stat_interrupt(bus);
self.check_lyc(bus);
}
}
fn stat_interrupt(&mut self, bus: &mut Bus) {
let prev_state = self.state;
let lyc_compare = PPU::get_lcd_y(bus) == bus.read(LCD_Y_COMPARE_ADDRESS);
PPU::set_lcd_status(bus, LCDStatus::LYCFlag, lyc_compare);
self.state =
(
lyc_compare &&
PPU::get_lcd_status(bus, LCDStatus::LYCInterrupt)
) ||
(
PPU::get_lcd_status(bus, LCDStatus::Mode2OAMInterrupt) &&
PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::SearchingOAM))
) || (
PPU::get_lcd_status(bus, LCDStatus::Mode0HBlankInterrupt) &&
PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::HBlank))
) || (
PPU::get_lcd_status(bus, LCDStatus::Mode1VBlankInterrupt) &&
PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::VBlank))
);
if self.state && !prev_state {
bus.set_interrupt_flag(Interrupt::LCDSTAT, self.state);
let state = self.prev_state;
self.prev_state = (PPU::get_lcd_status(bus, LCDStatus::Mode2OAMInterrupt) && PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::SearchingOAM))) ||
(PPU::get_lcd_status(bus, LCDStatus::Mode0HBlankInterrupt) && PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::HBlank))) ||
(PPU::get_lcd_status(bus, LCDStatus::Mode1VBlankInterrupt) && PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::VBlank)));
if self.prev_state && !state {
bus.set_interrupt_flag(Interrupt::LCDSTAT, true);
}
}
fn check_lyc(&mut self, bus: &mut Bus) {
let lyc_compare = PPU::get_lcd_y(bus) == bus.read(LCD_Y_COMPARE_ADDRESS);
PPU::set_lcd_status(bus, LCDStatus::LYCFlag, lyc_compare);
if !self.state && lyc_compare && PPU::get_lcd_status(bus, LCDStatus::LYCInterrupt) {
if lyc_compare && PPU::get_lcd_status(bus, LCDStatus::LYCInterrupt) {
bus.set_interrupt_flag(Interrupt::LCDSTAT, true);
self.state = true;
self.prev_state = true;
}
}
@ -279,7 +259,7 @@ impl PPU {
// but since we are on an emulator we can avoud that limitation
if self.sprite_buffer.len() >= 10 {
// todo!("Make a setting for the 10 sprites per scanline");
break;
// break;
}
let y = bus.read(addr);
let x = bus.read(addr + 1);
@ -324,7 +304,7 @@ impl PPU {
fn find_sprite_pixel(&self, lcd_x: u8, bus: &Bus) -> Option<Pixel> {
let lcd_y = PPU::get_lcd_y(bus);
for sprite in &self.sprite_buffer {
if let Some(pixel) = sprite.get_pixel(lcd_x, lcd_y, bus, self.last_bg_index) {
if let Some(pixel) = sprite.get_pixel(lcd_x, lcd_y, bus) {
return Some(pixel);
}
}
@ -414,23 +394,17 @@ impl PPU {
(bus.read(addr), bus.read(addr + 1))
}
fn get_window_pixel(&mut self, lcd_x: u8, bus: &Bus) -> Option<Pixel> {
fn get_window_pixel(lcd_x: u8, bus: &Bus) -> Option<Pixel> {
let lcd_y = PPU::get_lcd_y(bus);
let window_x = PPU::get_window_x(bus);
let window_y = PPU::get_window_y(bus);
if
!PPU::get_lcd_control(bus, LCDControl::WindowEnable) ||
lcd_x < window_x.saturating_sub(7) ||
lcd_y < window_y ||
window_y >= 144 ||
window_x.saturating_sub(7) >= 160
{
if !PPU::get_lcd_control(bus, LCDControl::WindowEnable) || lcd_x < (window_x.saturating_sub(7)) || window_y != lcd_y {
return None;
}
let x = lcd_x.wrapping_sub(window_x.saturating_sub(7));
let y = self.window_y_counter;
let y = lcd_y.wrapping_sub(window_y);
let default_mode = PPU::get_lcd_control(bus, LCDControl::TileAddressMode);
let tilemap_area = match PPU::get_lcd_control(bus, LCDControl::WindowTileMapAddress) {
@ -440,19 +414,19 @@ impl PPU {
let (tile_byte_1, tile_byte_2) = PPU::get_tile_bytes(x, y, tilemap_area, default_mode, bus);
let palette = bus.read(BACKGROUND_PALETTE_ADDRESS);
let pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2);
let index = pixels[(x as usize).rem_euclid(8)];
self.last_bg_index = index & 0b11;
let pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2, palette);
Some(PPU::get_pixel(PPU::get_palette(index, palette)))
Some(pixels[(x as usize).rem_euclid(8)])
}
fn get_background_pixel(&mut self, lcd_x: u8, bus: &Bus) -> Option<Pixel> {
if !PPU::get_lcd_control(bus, LCDControl::BackgroundPriority) {
return None;
}
let lcd_y = PPU::get_lcd_y(bus);
fn draw_line(&mut self, bus: &Bus, frame_buffer: &mut [u8]) {
let palette = bus.read(BACKGROUND_PALETTE_ADDRESS);
let lcd_y = PPU::get_lcd_y(bus);
if lcd_y as u32 >= LCD_HEIGHT {
return;
}
let mut lcd_x: u8 = 0;
while (lcd_x as u32) < LCD_WIDTH {
let y = lcd_y.wrapping_add(PPU::get_scroll_y(bus));
let x = lcd_x.wrapping_add(PPU::get_scroll_x(bus));
@ -463,36 +437,21 @@ impl PPU {
};
let (tile_byte_1, tile_byte_2) = PPU::get_tile_bytes(x, y, tilemap_area, default_mode, bus);
let bg_pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2);
let index = bg_pixels[x.rem_euclid(8) as usize];
self.last_bg_index = index & 0b11;
let bg_pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2, palette);
Some(PPU::get_pixel(PPU::get_palette(index, palette)))
}
fn draw_line(&mut self, bus: &Bus, frame_buffer: &mut [u8]) {
let lcd_y = PPU::get_lcd_y(bus);
if lcd_y as u32 >= LCD_HEIGHT {
return;
}
let mut lcd_x: u8 = 0;
let mut window_drawn = false;
while (lcd_x as u32) < LCD_WIDTH {
let idx = (lcd_x as usize + (lcd_y as usize * LCD_WIDTH as usize)) * 4;
if let Some(background_pixel) = self.get_background_pixel(lcd_x, bus) {
let rgba = PPU::get_rgba(background_pixel);
let pixel = bg_pixels[x.rem_euclid(8) as usize];
let rgba = PPU::get_rgba(pixel);
frame_buffer[idx] = rgba[0];
frame_buffer[idx + 1] = rgba[1];
frame_buffer[idx + 2] = rgba[2];
}
if let Some(window_pixel) = self.get_window_pixel(lcd_x, bus) {
window_drawn = true;
if let Some(window_pixel) = PPU::get_window_pixel(lcd_x, bus) {
let rgba = PPU::get_rgba(window_pixel);
frame_buffer[idx] = rgba[0];
frame_buffer[idx + 1] = rgba[1];
frame_buffer[idx + 2] = rgba[2];
}
if let Some(sprite_pixel) = self.find_sprite_pixel(lcd_x, bus) {
let rgba = PPU::get_rgba(sprite_pixel);
frame_buffer[idx] = rgba[0];
@ -501,9 +460,22 @@ impl PPU {
}
lcd_x += 1;
/* for pixel in bg_pixels {
let idx = (lcd_x as usize + (lcd_y as usize * LCD_WIDTH as usize)) * 4;
let rgba = PPU::get_rgba(pixel);
frame_buffer[idx] = rgba[0];
frame_buffer[idx + 1] = rgba[1];
frame_buffer[idx + 2] = rgba[2];
if let Some(window_pixel) = PPU::get_window_pixel(lcd_x, bus) {
let rgba = PPU::get_rgba(pixel);
frame_buffer[idx] = rgba[0];
frame_buffer[idx + 1] = rgba[1];
frame_buffer[idx + 2] = rgba[2];
}
if window_drawn {
self.window_y_counter += 1;
lcd_x += 1;
} */
}
}
@ -536,7 +508,7 @@ impl PPU {
}
}
fn get_byte_pixels(byte1: u8, byte2: u8) -> [u8; 8] {
fn get_two_bit_byte_pixels(byte1: u8, byte2: u8) -> [u8; 8] {
[
((byte1 >> 7) & 0b01) | ((byte2 >> 6) & 0b10),
((byte1 >> 6) & 0b01) | ((byte2 >> 5) & 0b10),
@ -548,4 +520,17 @@ impl PPU {
(byte1 & 0b01) | ((byte2 << 1) & 0b10),
]
}
fn get_byte_pixels(byte1: u8, byte2: u8, palette: u8) -> [Pixel; 8] {
[
PPU::get_pixel(PPU::get_palette(((byte1 >> 7) & 0b01) | ((byte2 >> 6) & 0b10), palette)),
PPU::get_pixel(PPU::get_palette(((byte1 >> 6) & 0b01) | ((byte2 >> 5) & 0b10), palette)),
PPU::get_pixel(PPU::get_palette(((byte1 >> 5) & 0b01) | ((byte2 >> 4) & 0b10), palette)),
PPU::get_pixel(PPU::get_palette(((byte1 >> 4) & 0b01) | ((byte2 >> 3) & 0b10), palette)),
PPU::get_pixel(PPU::get_palette(((byte1 >> 3) & 0b01) | ((byte2 >> 2) & 0b10), palette)),
PPU::get_pixel(PPU::get_palette(((byte1 >> 2) & 0b01) | ((byte2 >> 1) & 0b10), palette)),
PPU::get_pixel(PPU::get_palette(((byte1 >> 1) & 0b01) | (byte2 & 0b10), palette)),
PPU::get_pixel(PPU::get_palette((byte1 & 0b01) | ((byte2 << 1) & 0b10), palette)),
]
}
}

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@ -65,6 +65,7 @@ pub fn start_eventloop() {
},
Event::MainEventsCleared => {
emulator.run(Cycles(70224), pixels.get_frame());
// emulator.draw(pixels.get_frame());
thread::sleep(time::Duration::from_millis(1));
window.request_redraw();