README.md

@@ -6,12 +6,13 @@ This is just a fun project I'm making for learning and practice purposes. If you
 Any help or suggestion is welcome!
 
 ## TODO
-- [x] CPU implementation
+- [x] CPU Registers implementation
+- [x] CPU Instructions implementations
 - [ ] Interrupts
 - [ ] Timing
 - [ ] PPU implementations
 - [ ] Gameboy boot ROM
-- [x] Render the pixels
+- [ ] Render the pixels
 - [ ] Gameboy Color compatibility
 - [ ] Sound
 - [ ] Web Assembly support (because this is a Rust project and it has to support Web Assembly)

src/bus.rs

@@ -1,12 +1,5 @@
-use crate::utils::{
-    get_bit,
-    set_bit,
-    BitIndex,
-    join_bytes
-};
+use crate::utils::{join_bytes};
 use crate::rom::ROM;
-use crate::ppu::{PPU, LCDStatus, LCDStatusModeFlag};
-use crate::cpu::{InterruptFlag};
 
 pub struct AddressRange {
     begin: u16,
@@ -39,7 +32,6 @@ pub const NOT_USABLE: AddressRange                = AddressRange{begin: 0xFEA0,
 pub const IO_REGISTERS: AddressRange              = AddressRange{begin: 0xFF00, end: 0xFF7F};
 pub const HIGH_RAM: AddressRange                  = AddressRange{begin: 0xFF80, end: 0xFFFE};
 pub const INTERRUPT_ENABLE_REGISTER: AddressRange = AddressRange{begin: 0xFFFF, end: 0xFFFF};
-pub const INTERRUPT_FLAG_ADDRESS: u16 = 0xFF0F;
 
 pub struct Bus {
     game_rom: ROM,
@@ -48,8 +40,7 @@ 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("roms/cpu_instrs.gb".to_string()) {
+        let game_rom = match ROM::load_file("ignore/dmg-acid2.gb".to_string()) {
         // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/01-special.gb".to_string()) {
         // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/03-op sp,hl.gb".to_string()) {
         // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/04-op r,imm.gb".to_string()) {
@@ -73,12 +64,12 @@ impl Bus {
     pub fn read(&self, address: u16) -> u8 {
         if BANK_ZERO.in_range(address) || BANK_SWITCHABLE.in_range(address) {
             return self.game_rom.read(address);
-        } else if VIDEO_RAM.in_range(address) {
-            if PPU::get_lcd_status(self, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD)) {
-                return 0xFF
-            }
         } else if IO_REGISTERS.in_range(address) {
-            return self.data[address as usize];
+            return match address {
+                0xFF44 => 0x90,
+                0xFF4D => 0xFF,
+                _ => self.data[address as usize],
+            }
         }
         self.data[address as usize]
     }
@@ -103,13 +94,8 @@ impl Bus {
         } else if ECHO_RAM.in_range(address) {
             self.data[address as usize] = data;
             self.data[(WORK_RAM_1.begin() + (address - ECHO_RAM.begin())) as usize] = data; // Copy to the working RAM
-        } else if VIDEO_RAM.in_range(address) {
-            //if !PPU::get_lcd_status(self, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD)) {
-                self.data[address as usize] = data;
-            // }
-        } else {
-            self.data[address as usize] = data;
         }
+        self.data[address as usize] = data;
     }
 
     pub fn write_16bit(&mut self, address: u16, data: u16) {
@@ -117,15 +103,4 @@ impl Bus {
         self.write(address, bytes[0]);
         self.write(address.wrapping_add(1), bytes[1]);
     }
-
-    pub fn set_flag(&mut self, flag: InterruptFlag, val: bool) {
-        let byte = self.read(INTERRUPT_FLAG_ADDRESS);
-        self.write(INTERRUPT_FLAG_ADDRESS, match flag {
-           InterruptFlag::VBlank => set_bit(byte, val, BitIndex::I0),
-           InterruptFlag::LCDSTAT => set_bit(byte, val, BitIndex::I1),
-           InterruptFlag::Timer => set_bit(byte, val, BitIndex::I2),
-           InterruptFlag::Serial => set_bit(byte, val, BitIndex::I3),
-           InterruptFlag::Joypad => set_bit(byte, val, BitIndex::I4),
-        });
-    }
 }

src/cpu.rs

@@ -806,6 +806,8 @@ pub enum Opcode {
     PrefixCB(Box<Opcode>),
     IllegalInstruction,
 }
+// Frequency un Hz
+const FREQUENCY: f64 = 4194.304;
 
 // Store cycles in M
 #[derive(Debug, Copy, Clone)]

src/emulator.rs

@@ -20,8 +20,8 @@ impl Emulator {
     }
 
     pub fn draw(&mut self, frame: &mut [u8]) {
-        // self.ppu.draw_background(&mut self.bus);
-        let ppu_frame = self.ppu.get_rgba_frame();
+        self.ppu.draw_background(&self.bus);
+        let ppu_frame = self.ppu.get_rgba_frame(&self.bus);
         for (i, pixel) in frame.chunks_exact_mut(4).enumerate() {
             pixel.copy_from_slice(&ppu_frame[i]);
         }
@@ -30,7 +30,6 @@ impl Emulator {
     pub fn run(&mut self, cpu_cycles: Cycles) {
         self.cpu.reset_cycles();
         while self.cpu.get_cycles().0 <= cpu_cycles.0 {
-            self.ppu.do_cycle(&mut self.bus);
             self.cpu.run(&mut self.bus);
         }
     }

src/ppu.rs

@@ -5,7 +5,8 @@ use crate::utils::{
     to_bit_index,
 };
 use crate::bus::{Bus, AddressRange, BANK_ZERO, VIDEO_RAM};
-use crate::cpu::{Cycles, InterruptFlag};
+use crate::cpu::{Cycles};
+use rand::Rng;
 
 #[derive(Debug, Copy, Clone)]
 enum Pixel {
@@ -45,10 +46,8 @@ pub enum LCDStatus {
     ModeFlag(LCDStatusModeFlag),
 }
 
-pub const LCD_WIDTH: u32 = 160;
-pub const LCD_HEIGHT: u32 = 144;
-pub const WIDTH: u32 = LCD_WIDTH;
-pub const HEIGHT: u32 = LCD_HEIGHT;
+pub const WIDTH: u32 = 160;
+pub const HEIGHT: u32 = 144;
 pub const FRAME_BUFFER_LENGTH: u32 = WIDTH * HEIGHT;
 
 const LCD_CONTROL_ADDRESS: u16 = 0xFF40;
@@ -75,69 +74,10 @@ impl PPU {
     pub fn new() -> Self {
         Self {
             cycles: Cycles(0),
-            rgba_frame: [[0xFF, 0xFF, 0xFF, 0]; FRAME_BUFFER_LENGTH as usize],
+            rgba_frame: [[0, 0, 0xFF, 0]; FRAME_BUFFER_LENGTH as usize],
         }
     }
 
-    pub fn reset_cycles(&mut self) {
-        self.cycles.0 = 0;
-    }
-
-    pub fn increment_cycles(&mut self, cycles: Cycles) {
-        self.cycles.0 += cycles.0;
-    }
-
-    pub fn do_cycle(&mut self, bus: &mut Bus) {
-        // Mode 1 Vertical blank
-        if PPU::get_lcd_y(bus) >= 144 {
-            if PPU::get_lcd_y(bus) == 144 {
-                bus.set_flag(InterruptFlag::VBlank, true);
-                PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::VBlank), true);
-            }
-        } else {
-            if self.cycles.0 == 0 {
-                // Mode 2 OAM scan
-                PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::SearchingOAM), true);
-            } else if self.cycles.0 == 80 + 1 {
-                // Mode 3 drawing pixel line. This could also last 289 cycles
-                bus.set_flag(InterruptFlag::LCDSTAT, true);
-                self.draw_line(bus);
-                PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD), true);
-            } else if self.cycles.0 == 80 + 172 + 1 {
-                // Mode 0 Horizontal blank. This could last 87 or 204 cycles depending on the mode 3
-                bus.set_flag(InterruptFlag::LCDSTAT, true);
-                PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::HBlank), true);
-            }
-        }
-
-        let lyc_compare = PPU::get_lcd_y(bus) == bus.read(LCD_Y_COMPARE_ADDRESS);
-        PPU::set_lcd_status(bus, LCDStatus::LYCInterrupt, lyc_compare);
-        if lyc_compare {
-            bus.set_flag(InterruptFlag::LCDSTAT, true);
-        }
-        self.increment_cycles(Cycles(1));
-
-        // Horizontal scan completed
-        if self.cycles.0 > 456 {
-            self.reset_cycles();
-
-            PPU::set_lcd_y(bus, PPU::get_lcd_y(bus) + 1);
-
-            // Frame completed
-            if PPU::get_lcd_y(bus) > 153 {
-                PPU::set_lcd_y(bus, 0);
-            }
-        }
-    }
-
-    fn get_lcd_y(bus: &Bus) -> u8 {
-        bus.read(LCD_Y_ADDRESS)
-    }
-
-    fn set_lcd_y(bus: &mut Bus, val: u8) {
-        bus.write(LCD_Y_ADDRESS, val);
-    }
-
     fn get_scroll_x(bus: &Bus) -> u8 {
         bus.read(SCROLL_X_ADDRESS)
     }
@@ -154,7 +94,7 @@ impl PPU {
         bus.write(SCROLL_Y_ADDRESS, val);
     }
 
-    pub fn get_lcd_control(bus: &Bus, control: LCDControl) -> bool {
+    fn get_lcd_control(bus: &Bus, control: LCDControl) -> bool {
         let byte = bus.read(LCD_CONTROL_ADDRESS);
         match control {
             LCDControl::DisplayEnable => get_bit(byte, BitIndex::I7),
@@ -183,7 +123,7 @@ impl PPU {
         bus.write(LCD_CONTROL_ADDRESS, byte);
     }
 
-    pub fn get_lcd_status(bus: &Bus, status: LCDStatus) -> bool {
+    fn get_lcd_status(bus: &Bus, status: LCDStatus) -> bool {
         let byte = bus.read(LCD_STATUS_ADDRESS);
         match status {
             LCDStatus::LYCInterrupt => get_bit(byte, BitIndex::I6),
@@ -218,35 +158,6 @@ impl PPU {
         bus.write(LCD_STATUS_ADDRESS, byte);
     }
 
-    pub fn draw_line(&mut self, bus: &Bus) {
-        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 index_x = x as u16 / 8;
-            let index_y = (y as u16 / 8) * 32;
-            let index = index_x + index_y;
-            let tile_line = (y).rem_euclid(8) * 2;
-            let tile_number = bus.read(0x9800 + index as u16) as u16;
-            let addr = 0x8000 + tile_line as u16 + (tile_number * 16);
-
-            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);
-
-            for pixel in pixels {
-                let idx = lcd_x as usize + (lcd_y as usize * LCD_WIDTH as usize);
-                self.rgba_frame[idx] = PPU::get_rgba(pixel);
-                lcd_x += 1;
-            }
-        }
-    }
-
     fn get_pixel(two_bit_pixel: u8) -> Pixel {
         match two_bit_pixel {
             0x00 => Pixel::White,
@@ -266,6 +177,38 @@ impl PPU {
         }
     }
     
+    pub fn draw_background(&mut self, bus: &Bus) {
+        let mut idx = 0;
+        // let mut tile_line: u16 = 0;
+        let mut lcd_y: u8 = 0;
+        while lcd_y < 144 {
+            let mut lcd_x: u8 = 0;
+            while lcd_x < 160 {
+                let y = lcd_y.wrapping_add(PPU::get_scroll_y(bus));
+                let x = lcd_x.wrapping_add(PPU::get_scroll_x(bus));
+                let index_x = (x as u16 / 8);
+                let index_y = (y as u16 / 8) * 32;
+                let index = index_x + index_y;
+                let tile_line = (y).rem_euclid(8) * 2;
+                let index_byte = (bus.read(0x9800 + index as u16) as u16) * 16;
+
+                let tile_byte_1 = bus.read(0x8000 + tile_line as u16 + index_byte);
+                let tile_byte_2 = bus.read(0x8000 + tile_line as u16 + index_byte + 1);
+
+                let pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2);
+
+                for pixel in pixels {
+                    self.rgba_frame[idx] = PPU::get_rgba(pixel);
+                    idx += 1;
+                }
+
+                lcd_x += 8;
+            }
+            lcd_y += 1;
+            // tile_line += 2;
+        }
+    }
+
     fn get_byte_pixels(byte1: u8, byte2: u8) -> [Pixel; 8] {
         let mut pixels: [Pixel; 8] = [Pixel::White; 8];
         pixels[0] = PPU::get_pixel(((get_bit(byte1, BitIndex::I7) as u8) << 1) | (get_bit(byte2, BitIndex::I7) as u8));
@@ -279,7 +222,7 @@ impl PPU {
         pixels
     }
 
-    pub fn get_rgba_frame(&self) -> &[[u8; 4]; FRAME_BUFFER_LENGTH as usize] {
+    pub fn get_rgba_frame(&self, bus: &Bus) -> &[[u8; 4]; FRAME_BUFFER_LENGTH as usize] {
         &self.rgba_frame
     }
 }

src/render.rs

@@ -38,6 +38,7 @@ pub fn start_eventloop() {
 
     let mut emulator = Emulator::new();
 
+    let mut count: usize = 0;
     event_loop.run(move |event, _, control_flow| {
         // Handle input events
         if input.update(&event) {
@@ -65,7 +66,7 @@ pub fn start_eventloop() {
                 emulator.run(Cycles(70224));
                 emulator.draw(pixels.get_frame());
 
-                // thread::sleep(time::Duration::from_millis(14));
+                thread::sleep(time::Duration::from_millis(14));
                 window.request_redraw();
             },
             Event::RedrawRequested(_) => {