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Fix bug with LCD enable and LY=0 and disabling background when bit 0 is reset

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This commit is contained in:
Franco Colmenarez 2021-11-08 19:40:30 -05:00
parent f7ca3fcc25
commit b92160dee4
3 changed files with 64 additions and 49 deletions
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10
src/bus.rs
View File

@ -57,7 +57,7 @@ pub struct Bus {
impl Bus {
pub fn new() -> Self {
let game_rom = match ROM::load_file("ignore/tetris.gb".to_string()) {
let game_rom = match ROM::load_file("ignore/dmg-acid2.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()) {
@ -144,8 +144,12 @@ impl Bus {
} else if address == TIMER_DIVIDER_REGISTER_ADDRESS {
self.reset_timer = true;
} else if address == LCD_CONTROL_ADDRESS && get_bit(data, BitIndex::I7) {
self.data[address as usize] = data;
self.data[LCD_Y_ADDRESS as usize] = 0x00;
if get_bit(data, BitIndex::I7) && !get_bit(self.data[address as usize], BitIndex::I7) {
// LCD is turned on
println!("LCD turned on");
self.data[address as usize] = data;
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 {

102
src/ppu.rs
View File

@ -90,7 +90,7 @@ pub enum LCDStatus {
}
pub struct PPU {
prev_state: bool,
state: bool,
cycles: Cycles,
sprite_buffer: Vec<Sprite>,
}
@ -171,7 +171,7 @@ impl Sprite {
impl PPU {
pub fn new() -> Self {
Self {
prev_state: false,
state: false,
cycles: Cycles(0),
sprite_buffer: Vec::new(),
}
@ -199,8 +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
self.draw_line(bus, frame_buffer);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD), true);
self.draw_line(bus, frame_buffer);
} 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);
@ -224,26 +224,42 @@ impl PPU {
if PPU::get_lcd_y(bus) > 153 {
PPU::set_lcd_y(bus, 0);
}
self.check_lyc(bus);
// self.check_lyc(bus);
self.stat_interrupt(bus);
}
}
fn stat_interrupt(&mut self, bus: &mut Bus) {
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);
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 {
println!("LCDSTAT interrupt");
bus.set_interrupt_flag(Interrupt::LCDSTAT, self.state);
}
}
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 lyc_compare && PPU::get_lcd_status(bus, LCDStatus::LYCInterrupt) {
if !self.state && lyc_compare && PPU::get_lcd_status(bus, LCDStatus::LYCInterrupt) {
bus.set_interrupt_flag(Interrupt::LCDSTAT, true);
self.prev_state = true;
self.state = true;
}
}
@ -419,32 +435,44 @@ impl PPU {
Some(pixels[(x as usize).rem_euclid(8)])
}
fn draw_line(&mut self, bus: &Bus, frame_buffer: &mut [u8]) {
fn get_background_pixel(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);
let palette = bus.read(BACKGROUND_PALETTE_ADDRESS);
let y = lcd_y.wrapping_add(PPU::get_scroll_y(bus));
let x = lcd_x.wrapping_add(PPU::get_scroll_x(bus));
let default_mode = PPU::get_lcd_control(bus, LCDControl::TileAddressMode);
let tilemap_area = match PPU::get_lcd_control(bus, LCDControl::BackgroundTileMapAddress) {
true => 0x9C00,
false => 0x9800,
};
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, palette);
let pixel = bg_pixels[x.rem_euclid(8) as usize];
Some(pixel)
}
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;
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));
let default_mode = PPU::get_lcd_control(bus, LCDControl::TileAddressMode);
let tilemap_area = match PPU::get_lcd_control(bus, LCDControl::BackgroundTileMapAddress) {
true => 0x9C00,
false => 0x9800,
};
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, palette);
let idx = (lcd_x as usize + (lcd_y as usize * LCD_WIDTH as usize)) * 4;
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(background_pixel) = PPU::get_background_pixel(lcd_x, bus) {
let rgba = PPU::get_rgba(background_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(window_pixel);
frame_buffer[idx] = rgba[0];
@ -460,22 +488,6 @@ 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];
}
lcd_x += 1;
} */
}
}

1
src/render.rs
View File

@ -65,7 +65,6 @@ 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();