Experimental background rendering with scrolling

.gitignore

@@ -1,2 +1,3 @@
 /target
 *.log
+/ignore

src/bus.rs

@@ -40,7 +40,8 @@ pub struct Bus {
 
 impl Bus {
     pub fn new() -> Self {
-        let game_rom = match ROM::load_file("roms/cpu_instrs_individual/01-special.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()) {
         // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/05-op rp.gb".to_string()) {
@@ -51,7 +52,8 @@ impl Bus {
         // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/10-bit ops.gb".to_string()) {
         // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/11-op a,(hl).gb".to_string()) {
             Ok(rom) => rom,
-            _ => ROM::from_bytes(&[0; 0xFFFF])
+            // _ => ROM::from_bytes(&[0; 0xFFFF])
+            _ => panic!("Could not read ROM"),
         };
         Self {
             data: [0x00; 0x10000],

src/emulator.rs

@@ -23,7 +23,6 @@ impl Emulator {
         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() {
-            let rgba = [0x5e, 0x48, 0xe8, 0xff];
             pixel.copy_from_slice(&ppu_frame[i]);
         }
     }

src/ppu.rs

@@ -2,20 +2,23 @@ use crate::utils::{
     BitIndex,
     get_bit,
     set_bit,
+    to_bit_index,
 };
-use crate::bus::{Bus, BANK_ZERO, VIDEO_RAM};
+use crate::bus::{Bus, AddressRange, BANK_ZERO, VIDEO_RAM};
+use crate::cpu::{Cycles};
 use rand::Rng;
 
+#[derive(Debug, Copy, Clone)]
+enum Pixel {
+    White,
+    Light,
+    Dark,
+    Black,
+}
+
+#[derive(Debug, Copy, Clone)]
 struct ColorPalette(u8, u8, u8, u8);
 
-struct Tile {
-
-}
-
-struct Sprite {
-}
-
-
 pub enum LCDControl {
     DisplayEnable,
     WindowTileMapAddress,
@@ -50,8 +53,8 @@ pub const FRAME_BUFFER_LENGTH: u32 = WIDTH * HEIGHT;
 const LCD_CONTROL_ADDRESS: u16 = 0xFF40;
 const LCD_STATUS_ADDRESS: u16 = 0xFF41;
 
-const SCROLL_X_ADDRESS: u16 = 0xFF42;
-const SCROLL_Y_ADDRESS: u16 = 0xFF43;
+const SCROLL_Y_ADDRESS: u16 = 0xFF42;
+const SCROLL_X_ADDRESS: u16 = 0xFF43;
 const LCD_Y_ADDRESS: u16 = 0xFF44;
 const LCD_Y_COMPARE_ADDRESS: u16 = 0xFF45;
 const DMA_ADDRESS: u16 = 0xFF46;
@@ -60,49 +63,21 @@ const OBJECT_PALETTE_0_ADDRESS: u16 = 0xFF48;
 const OBJECT_PALETTE_1_ADDRESS: u16 = 0xFF49;
 const WINDOW_X_ADDRESS: u16 = 0xFF4A;
 const WINDOW_Y_ADDRESS: u16 = 0xFF4B;
-
-pub struct Window {}
-
-impl Window {
-    pub fn new() -> Self {
-        Self {}
-    }
-
-    fn get_x(bus: &Bus) -> u8 {
-        bus.read(WINDOW_X_ADDRESS)
-    }
-
-    fn set_x(bus: &mut Bus, val: u8) {
-        bus.write(WINDOW_X_ADDRESS, val);
-    }
-
-    fn get_y(bus: &Bus) -> u8 {
-        bus.read(WINDOW_Y_ADDRESS)
-    }
-
-    fn set_y(bus: &mut Bus, val: u8) {
-        bus.write(WINDOW_Y_ADDRESS, val);
-    }
-}
+const TILE_MAP_ADDRESS: u16 = 0x9800;
 
 pub struct PPU {
-    window: Window,
-
+    cycles: Cycles,
     rgba_frame: [[u8; 4]; FRAME_BUFFER_LENGTH as usize],
 }
 
 impl PPU {
     pub fn new() -> Self {
         Self {
+            cycles: Cycles(0),
             rgba_frame: [[0, 0, 0xFF, 0]; FRAME_BUFFER_LENGTH as usize],
-            window: Window::new(),
         }
     }
 
-    fn get_sprite(address: u16) {
-
-    }
-
     fn get_scroll_x(bus: &Bus) -> u8 {
         bus.read(SCROLL_X_ADDRESS)
     }
@@ -183,46 +158,67 @@ impl PPU {
         bus.write(LCD_STATUS_ADDRESS, byte);
     }
 
-    fn get_rgba_pixel(two_bit_pixel: u8) -> [u8; 4] {
+    fn get_pixel(two_bit_pixel: u8) -> Pixel {
         match two_bit_pixel {
-            0x00 => [255, 255, 255, 255],
-            0x01 => [192, 192, 192, 0],
-            0x10 => [128, 128, 128, 0],
-            0x11 => [0, 0, 0, 0],
-            _ => [0, 0, 0, 0],
+            0x00 => Pixel::White,
+            0x01 => Pixel::Light,
+            0x10 => Pixel::Dark,
+            0x11 => Pixel::Black,
+            _ => Pixel::Black,
         }
     }
 
+    fn get_rgba(pixel: Pixel) -> [u8; 4] {
+        match pixel {
+            Pixel::White => [255, 255, 255, 0],
+            Pixel::Light => [192, 192, 192, 0],
+            Pixel::Dark  => [81, 81, 81, 0],
+            Pixel::Black => [0, 0, 0, 0],
+        }
+    }
+    
     pub fn draw_background(&mut self, bus: &Bus) {
-        let mut pointer = VIDEO_RAM.begin();
-        let mut pixels_drawn: usize = 0;
-        while pixels_drawn < FRAME_BUFFER_LENGTH as usize {
-            let byte1 = bus.read(pointer);
-            let byte2 = bus.read(pointer + 1);
-            let pixels = PPU::get_byte_pixels(byte1, byte2);
-            self.rgba_frame[pixels_drawn]     = PPU::get_rgba_pixel(pixels[0]);
-            self.rgba_frame[pixels_drawn + 1] = PPU::get_rgba_pixel(pixels[1]);
-            self.rgba_frame[pixels_drawn + 2] = PPU::get_rgba_pixel(pixels[2]);
-            self.rgba_frame[pixels_drawn + 3] = PPU::get_rgba_pixel(pixels[3]);
-            self.rgba_frame[pixels_drawn + 4] = PPU::get_rgba_pixel(pixels[4]);
-            self.rgba_frame[pixels_drawn + 5] = PPU::get_rgba_pixel(pixels[5]);
-            self.rgba_frame[pixels_drawn + 6] = PPU::get_rgba_pixel(pixels[6]);
-            self.rgba_frame[pixels_drawn + 7] = PPU::get_rgba_pixel(pixels[7]);
-            pixels_drawn += 8;
-            pointer += 2;
+        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) -> [u8; 8] {
-        let mut pixels: [u8; 8] = [0; 8];
-        pixels[0] = ((get_bit(byte1, BitIndex::I7) as u8) << 1) | (get_bit(byte2, BitIndex::I7) as u8);
-        pixels[1] = ((get_bit(byte1, BitIndex::I6) as u8) << 1) | (get_bit(byte2, BitIndex::I6) as u8);
-        pixels[2] = ((get_bit(byte1, BitIndex::I5) as u8) << 1) | (get_bit(byte2, BitIndex::I5) as u8);
-        pixels[3] = ((get_bit(byte1, BitIndex::I4) as u8) << 1) | (get_bit(byte2, BitIndex::I4) as u8);
-        pixels[4] = ((get_bit(byte1, BitIndex::I3) as u8) << 1) | (get_bit(byte2, BitIndex::I3) as u8);
-        pixels[5] = ((get_bit(byte1, BitIndex::I2) as u8) << 1) | (get_bit(byte2, BitIndex::I2) as u8);
-        pixels[6] = ((get_bit(byte1, BitIndex::I1) as u8) << 1) | (get_bit(byte2, BitIndex::I1) as u8);
-        pixels[7] = ((get_bit(byte1, BitIndex::I0) as u8) << 1) | (get_bit(byte2, BitIndex::I0) as u8);
+    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));
+        pixels[1] = PPU::get_pixel(((get_bit(byte1, BitIndex::I6) as u8) << 1) | (get_bit(byte2, BitIndex::I6) as u8));
+        pixels[2] = PPU::get_pixel(((get_bit(byte1, BitIndex::I5) as u8) << 1) | (get_bit(byte2, BitIndex::I5) as u8));
+        pixels[3] = PPU::get_pixel(((get_bit(byte1, BitIndex::I4) as u8) << 1) | (get_bit(byte2, BitIndex::I4) as u8));
+        pixels[4] = PPU::get_pixel(((get_bit(byte1, BitIndex::I3) as u8) << 1) | (get_bit(byte2, BitIndex::I3) as u8));
+        pixels[5] = PPU::get_pixel(((get_bit(byte1, BitIndex::I2) as u8) << 1) | (get_bit(byte2, BitIndex::I2) as u8));
+        pixels[6] = PPU::get_pixel(((get_bit(byte1, BitIndex::I1) as u8) << 1) | (get_bit(byte2, BitIndex::I1) as u8));
+        pixels[7] = PPU::get_pixel(((get_bit(byte1, BitIndex::I0) as u8) << 1) | (get_bit(byte2, BitIndex::I0) as u8));
         pixels
     }
 

src/render.rs

@@ -2,6 +2,8 @@ use crate::emulator::Emulator;
 use crate::cpu::{CPU, Cycles};
 use crate::ppu::{WIDTH, HEIGHT};
 
+use std::{thread, time};
+
 use log::error;
 use pixels::{Error, Pixels, SurfaceTexture};
 use winit::dpi::LogicalSize;
@@ -62,10 +64,12 @@ pub fn start_eventloop() {
             },
             Event::MainEventsCleared => {
                 emulator.run(Cycles(70224));
+                emulator.draw(pixels.get_frame());
+
+                thread::sleep(time::Duration::from_millis(14));
                 window.request_redraw();
             },
             Event::RedrawRequested(_) => {
-                emulator.draw(pixels.get_frame());
                 if pixels
                     .render()
                     .map_err(|e| error!("pixels.render() failed: {}", e))

src/utils.rs

@@ -10,6 +10,20 @@ pub enum BitIndex {
     I7,
 }
 
+pub fn to_bit_index(index: u8) -> BitIndex {
+    match index {
+        0 => BitIndex::I0,
+        1 => BitIndex::I1,
+        2 => BitIndex::I2,
+        3 => BitIndex::I3,
+        4 => BitIndex::I4,
+        5 => BitIndex::I5,
+        6 => BitIndex::I6,
+        7 => BitIndex::I7,
+        _ => BitIndex::I7,
+    }
+}
+
 pub fn get_bit_index(index: BitIndex) -> u8 {
     match index {
         BitIndex::I0 => 0,