README.md

@@ -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)

src/bus.rs

@@ -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 {

src/ppu.rs

@@ -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)),
+        ]
+    }
 }

src/render.rs

@@ -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();