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6 changed files with 185 additions and 40 deletions

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@ -11,7 +11,8 @@ use crate::ppu::{
LCDStatusModeFlag, LCDStatusModeFlag,
LCD_STATUS_ADDRESS, LCD_STATUS_ADDRESS,
LCD_CONTROL_ADDRESS, LCD_CONTROL_ADDRESS,
LCD_Y_ADDRESS LCD_Y_ADDRESS,
DMA_ADDRESS,
}; };
use crate::cpu::{Interrupt}; use crate::cpu::{Interrupt};
use crate::timer::{TIMER_DIVIDER_REGISTER_ADDRESS}; use crate::timer::{TIMER_DIVIDER_REGISTER_ADDRESS};
@ -55,11 +56,12 @@ pub struct Bus {
game_rom: ROM, game_rom: ROM,
data: [u8; 0x10000], data: [u8; 0x10000],
pub reset_timer: bool, pub reset_timer: bool,
pub joypad: Joypad,
} }
impl Bus { impl Bus {
pub fn new() -> Self { pub fn new() -> Self {
let game_rom = match ROM::load_file("ignore/m3_scy_change.gb".to_string()) { 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("roms/cpu_instrs.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/01-special.gb".to_string()) {
// let game_rom = match ROM::load_file("roms/cpu_instrs_individual/02-interrupts.gb".to_string()) { // let game_rom = match ROM::load_file("roms/cpu_instrs_individual/02-interrupts.gb".to_string()) {
@ -104,12 +106,18 @@ impl Bus {
data, data,
game_rom, game_rom,
reset_timer: false, reset_timer: false,
joypad: Joypad::new(),
} }
} }
pub fn read(&self, address: u16) -> u8 { pub fn read(&self, address: u16) -> u8 {
if BANK_ZERO.in_range(address) || BANK_SWITCHABLE.in_range(address) { if BANK_ZERO.in_range(address) || BANK_SWITCHABLE.in_range(address) {
return self.game_rom.read(address); return self.game_rom.read(address);
} else if address == INTERRUPT_ENABLE_ADDRESS || address == INTERRUPT_FLAG_ADDRESS {
return 0b11100000 | self.data[address as usize];
} else if address == JOYPAD_ADDRESS {
return self.joypad.read(self.data[address as usize]);
} }
self.data[address as usize] self.data[address as usize]
} }
@ -147,6 +155,16 @@ impl Bus {
} else if address == JOYPAD_ADDRESS { } else if address == JOYPAD_ADDRESS {
let byte = self.data[address as usize]; let byte = self.data[address as usize];
self.data[address as usize] = (data & 0b11110000) | (byte & 0b00001111); self.data[address as usize] = (data & 0b11110000) | (byte & 0b00001111);
} else if address == DMA_ADDRESS {
// the idea is: when something gets written to $FF46, multiply it by 0x100, then copy 160 bytes starting from that memory location into OAM
self.data[address as usize] = data;
let source = (data as usize) * 0x100;
let mut count = 0;
let oam_addr = SPRITE_ATTRIBUTE_TABLE.begin() as usize;
while count < 160 {
self.data[oam_addr + count] = self.data[source + count];
count += 1;
}
} else { } else {
self.data[address as usize] = data; self.data[address as usize] = data;
} }

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@ -911,7 +911,7 @@ impl CPU {
} }
pub fn handle_interrupt(&mut self, bus: &mut Bus, interrupt: Interrupt) { pub fn handle_interrupt(&mut self, bus: &mut Bus, interrupt: Interrupt) {
println!("Interrupt: {:?}", interrupt); // println!("Interrupt: {:?}", interrupt);
bus.set_interrupt_flag(interrupt, false); bus.set_interrupt_flag(interrupt, false);
self.ime = false; self.ime = false;
self.registers.decrement(Register::PC, 3); self.registers.decrement(Register::PC, 3);

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@ -13,18 +13,15 @@ pub struct Emulator {
ppu: PPU, ppu: PPU,
bus: Bus, bus: Bus,
timer: Timer, timer: Timer,
joypad: Joypad,
} }
impl Emulator { impl Emulator {
pub fn new() -> Self { pub fn new() -> Self {
let mut joypad: Joypad = Joypad::new();
Self { Self {
cpu: CPU::new(), cpu: CPU::new(),
ppu: PPU::new(), ppu: PPU::new(),
bus: Bus::new(), bus: Bus::new(),
timer: Timer::new(), timer: Timer::new(),
joypad: Joypad::new(),
} }
} }
@ -32,68 +29,68 @@ impl Emulator {
let mut change = false; let mut change = false;
if input.key_pressed(VirtualKeyCode::K) { if input.key_pressed(VirtualKeyCode::K) {
change = true; change = true;
self.joypad.press(Button::A); self.bus.joypad.press(Button::A);
} }
if input.key_pressed(VirtualKeyCode::J) { if input.key_pressed(VirtualKeyCode::J) {
change = true; change = true;
self.joypad.press(Button::B); self.bus.joypad.press(Button::B);
} }
if input.key_pressed(VirtualKeyCode::W) { if input.key_pressed(VirtualKeyCode::W) {
change = true; change = true;
self.joypad.press(Button::Up); self.bus.joypad.press(Button::Up);
} }
if input.key_pressed(VirtualKeyCode::S) { if input.key_pressed(VirtualKeyCode::S) {
change = true; change = true;
self.joypad.press(Button::Down); self.bus.joypad.press(Button::Down);
} }
if input.key_pressed(VirtualKeyCode::A) { if input.key_pressed(VirtualKeyCode::A) {
change = true; change = true;
self.joypad.press(Button::Left); self.bus.joypad.press(Button::Left);
} }
if input.key_pressed(VirtualKeyCode::D) { if input.key_pressed(VirtualKeyCode::D) {
change = true; change = true;
self.joypad.press(Button::Right); self.bus.joypad.press(Button::Right);
} }
if input.key_pressed(VirtualKeyCode::N) { if input.key_pressed(VirtualKeyCode::N) {
change = true; change = true;
self.joypad.press(Button::Start); self.bus.joypad.press(Button::Start);
} }
if input.key_pressed(VirtualKeyCode::B) { if input.key_pressed(VirtualKeyCode::B) {
change = true; change = true;
self.joypad.press(Button::Select); self.bus.joypad.press(Button::Select);
} }
if input.key_released(VirtualKeyCode::K) { if input.key_released(VirtualKeyCode::K) {
change = true; change = true;
self.joypad.release(Button::A); self.bus.joypad.release(Button::A);
} }
if input.key_released(VirtualKeyCode::J) { if input.key_released(VirtualKeyCode::J) {
change = true; change = true;
self.joypad.release(Button::B); self.bus.joypad.release(Button::B);
} }
if input.key_released(VirtualKeyCode::W) { if input.key_released(VirtualKeyCode::W) {
change = true; change = true;
self.joypad.release(Button::Up); self.bus.joypad.release(Button::Up);
} }
if input.key_released(VirtualKeyCode::S) { if input.key_released(VirtualKeyCode::S) {
change = true; change = true;
self.joypad.release(Button::Down); self.bus.joypad.release(Button::Down);
} }
if input.key_released(VirtualKeyCode::A) { if input.key_released(VirtualKeyCode::A) {
change = true; change = true;
self.joypad.release(Button::Left); self.bus.joypad.release(Button::Left);
} }
if input.key_released(VirtualKeyCode::D) { if input.key_released(VirtualKeyCode::D) {
change = true; change = true;
self.joypad.release(Button::Right); self.bus.joypad.release(Button::Right);
} }
if input.key_released(VirtualKeyCode::N) { if input.key_released(VirtualKeyCode::N) {
change = true; change = true;
self.joypad.release(Button::Start); self.bus.joypad.release(Button::Start);
} }
if input.key_released(VirtualKeyCode::B) { if input.key_released(VirtualKeyCode::B) {
change = true; change = true;
self.joypad.release(Button::Select); self.bus.joypad.release(Button::Select);
} }
if change { if change {
self.bus.set_interrupt_flag(Interrupt::Joypad, true); self.bus.set_interrupt_flag(Interrupt::Joypad, true);
@ -102,7 +99,7 @@ impl Emulator {
pub fn run(&mut self, cpu_cycles: Cycles, frame_buffer: &mut [u8]) { pub fn run(&mut self, cpu_cycles: Cycles, frame_buffer: &mut [u8]) {
self.cpu.reset_cycles(); self.cpu.reset_cycles();
while self.cpu.get_cycles().0 <= cpu_cycles.0 { while self.cpu.get_cycles().to_t() <= cpu_cycles.0 {
self.cpu.run(&mut self.bus); self.cpu.run(&mut self.bus);
if self.bus.reset_timer { if self.bus.reset_timer {
self.bus.reset_timer = false; self.bus.reset_timer = false;

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@ -41,7 +41,6 @@ impl Joypad {
} }
pub fn press(&mut self, button: Button) { pub fn press(&mut self, button: Button) {
println!("{:?} pressed", button);
match button { match button {
Button::A => self.a = true, Button::A => self.a = true,
Button::B => self.b = true, Button::B => self.b = true,
@ -55,7 +54,6 @@ impl Joypad {
} }
pub fn release(&mut self, button: Button) { pub fn release(&mut self, button: Button) {
println!("{:?} released", button);
match button { match button {
Button::A => self.a = false, Button::A => self.a = false,
Button::B => self.b = false, Button::B => self.b = false,
@ -68,8 +66,7 @@ impl Joypad {
}; };
} }
pub fn read(&self, bus: &mut Bus) -> u8 { pub fn read(&self, byte: u8) -> u8 {
let byte = bus.read(JOYPAD_ADDRESS);
let direction = !get_bit(byte, BitIndex::I4); let direction = !get_bit(byte, BitIndex::I4);
let action = !get_bit(byte, BitIndex::I5); let action = !get_bit(byte, BitIndex::I5);

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@ -4,7 +4,7 @@ use crate::utils::{
set_bit, set_bit,
to_bit_index, to_bit_index,
}; };
use crate::bus::{Bus, AddressRange, BANK_ZERO, VIDEO_RAM}; use crate::bus::{Bus, AddressRange, BANK_ZERO, VIDEO_RAM, SPRITE_ATTRIBUTE_TABLE};
use crate::cpu::{Cycles, Interrupt}; use crate::cpu::{Cycles, Interrupt};
pub const LCD_WIDTH: u32 = 160; pub const LCD_WIDTH: u32 = 160;
@ -94,11 +94,60 @@ pub struct PPU {
prev_state: bool, prev_state: bool,
cycles: Cycles, cycles: Cycles,
rgba_frame: [[u8; 4]; FRAME_BUFFER_LENGTH as usize], rgba_frame: [[u8; 4]; FRAME_BUFFER_LENGTH as usize],
sprite_buffer: Vec<Sprite>,
} }
enum TileNumber { struct Sprite {
Base(u16), x: u8,
Absolute(u8), y: u8,
tile_number: u8,
x_flip: bool,
y_flip: bool,
over_bg: bool,
palette_one: bool,
is_long: bool,
}
impl Sprite {
pub fn x(&self) -> u8 {
self.x
}
pub fn get_pixel(&self, lcd_x: u8, lcd_y: u8, bus: &Bus) -> Option<Pixel> {
todo!("Implement sprite flipping");
if lcd_x < self.x.saturating_sub(8) || lcd_x >= self.x {
return None;
}
let height: u8 = match self.is_long {
true => 16,
false => 8,
};
let x = lcd_x.saturating_sub(self.x.saturating_sub(8));
let y = lcd_y.saturating_sub(self.y .saturating_sub(16));
let tile_line = y.rem_euclid(height) * 2;
let addr = 0x8000 + (self.tile_number as u16 * 16) + tile_line as u16;
let tile_byte_1 = bus.read(addr);
let tile_byte_2 = bus.read(addr + 1);
let pixel_index = (x as usize).rem_euclid(8);
if PPU::get_two_bit_byte_pixels(tile_byte_1, tile_byte_2)[pixel_index] == 0 {
return None;
}
let palette = match self.palette_one {
true => bus.read(OBJECT_PALETTE_1_ADDRESS),
false => bus.read(OBJECT_PALETTE_0_ADDRESS),
};
let pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2, palette);
Some(pixels[pixel_index])
}
} }
impl PPU { impl PPU {
@ -107,6 +156,7 @@ impl PPU {
prev_state: false, prev_state: false,
cycles: Cycles(0), cycles: Cycles(0),
rgba_frame: [[0xFF, 0xFF, 0xFF, 0]; FRAME_BUFFER_LENGTH as usize], rgba_frame: [[0xFF, 0xFF, 0xFF, 0]; FRAME_BUFFER_LENGTH as usize],
sprite_buffer: Vec::new(),
} }
} }
@ -120,7 +170,7 @@ impl PPU {
pub fn do_cycles(&mut self, bus: &mut Bus, cycles: Cycles, frame_buffer: &mut [u8]) { pub fn do_cycles(&mut self, bus: &mut Bus, cycles: Cycles, frame_buffer: &mut [u8]) {
let mut count = 0; let mut count = 0;
while count < cycles.0 { while count < cycles.to_t() {
self.cycle(bus, frame_buffer); self.cycle(bus, frame_buffer);
count += 1; count += 1;
} }
@ -137,6 +187,7 @@ impl PPU {
// Mode 2 OAM scan // Mode 2 OAM scan
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::SearchingOAM), true); PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::SearchingOAM), true);
self.stat_interrupt(bus); self.stat_interrupt(bus);
self.oam_search(bus);
} else if self.cycles.0 == 80 + 1 { } else if self.cycles.0 == 80 + 1 {
// Mode 3 drawing pixel line. This could also last 289 cycles // Mode 3 drawing pixel line. This could also last 289 cycles
self.draw_line(bus, frame_buffer); self.draw_line(bus, frame_buffer);
@ -189,6 +240,71 @@ impl PPU {
} }
} }
fn oam_search(&mut self, bus: &Bus) {
self.sprite_buffer = Vec::new();
if !PPU::get_lcd_control(bus, LCDControl::ObjectEnable) {
return;
}
let long_sprites = PPU::get_lcd_control(bus, LCDControl::ObjectSize);
let mut addr = SPRITE_ATTRIBUTE_TABLE.begin();
while addr <= SPRITE_ATTRIBUTE_TABLE.end() {
// The gameboy only supports 10 sprites per line,
// 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;
}
let y = bus.read(addr);
let x = bus.read(addr + 1);
if x == 0 {
addr += 4;
continue;
}
let sprite_height: u8 = match long_sprites {
true => 16,
false => 8,
};
let lcd_y = PPU::get_lcd_y(bus).saturating_add(16);
if lcd_y < y || lcd_y > (y + sprite_height) {
addr += 4;
continue;
}
let tile_number = bus.read(addr + 2);
let attributes = bus.read(addr + 3);
self.sprite_buffer.push(Sprite {
x,
y,
tile_number,
is_long: long_sprites,
palette_one: get_bit(attributes, BitIndex::I4),
x_flip: get_bit(attributes, BitIndex::I5),
y_flip: get_bit(attributes, BitIndex::I6),
over_bg: get_bit(attributes, BitIndex::I7),
});
addr += 4;
}
self.sprite_buffer.sort_by(|a, b| a.x().cmp(&b.x()));
}
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) {
return Some(pixel);
}
}
return None;
}
fn get_lcd_y(bus: &Bus) -> u8 { fn get_lcd_y(bus: &Bus) -> u8 {
bus.read(LCD_Y_ADDRESS) bus.read(LCD_Y_ADDRESS)
} }
@ -258,15 +374,12 @@ impl PPU {
bus.force_write(LCD_STATUS_ADDRESS, byte); bus.force_write(LCD_STATUS_ADDRESS, byte);
} }
fn get_tile_bytes(x: u8, y: u8, tile_number_type: TileNumber, default_method: bool, bus: &Bus) -> (u8, u8) { fn get_tile_bytes(x: u8, y: u8, tilemap_area: u16, default_method: bool, bus: &Bus) -> (u8, u8) {
let index_x = x as u16 / 8; let index_x = x as u16 / 8;
let index_y = (y as u16 / 8) * 32; let index_y = (y as u16 / 8) * 32;
let index = index_x + index_y; let index = index_x + index_y;
let tile_line = (y).rem_euclid(8) * 2; let tile_line = (y).rem_euclid(8) * 2;
let tile_number = match tile_number_type { let tile_number = bus.read(tilemap_area + index as u16) as u16;
TileNumber::Base(base) => bus.read(base + index as u16),
TileNumber::Absolute(num) => bus.read(0x8000 + num as u16),
} as u16;
let addr = if default_method { let addr = if default_method {
0x8000 + tile_line as u16 + (tile_number * 16) 0x8000 + tile_line as u16 + (tile_number * 16)
} else { } else {
@ -296,7 +409,7 @@ impl PPU {
true => 0x9C00, true => 0x9C00,
false => 0x9800, false => 0x9800,
}; };
let (tile_byte_1, tile_byte_2) = PPU::get_tile_bytes(x, y, TileNumber::Base(tilemap_area), default_mode, bus); 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 palette = bus.read(BACKGROUND_PALETTE_ADDRESS);
let pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2, palette); let pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2, palette);
@ -320,7 +433,7 @@ impl PPU {
true => 0x9C00, true => 0x9C00,
false => 0x9800, false => 0x9800,
}; };
let (tile_byte_1, tile_byte_2) = PPU::get_tile_bytes(x, y, TileNumber::Base(tilemap_area), default_mode, bus); 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 bg_pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2, palette);
@ -337,6 +450,13 @@ impl PPU {
frame_buffer[idx + 2] = rgba[2]; 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];
frame_buffer[idx + 1] = rgba[1];
frame_buffer[idx + 2] = rgba[2];
}
lcd_x += 1; lcd_x += 1;
/* for pixel in bg_pixels { /* for pixel in bg_pixels {
@ -386,6 +506,19 @@ impl PPU {
} }
} }
fn get_two_bit_byte_pixels(byte1: u8, byte2: u8) -> [u8; 8] {
[
((byte1 >> 7) & 0b01) | ((byte2 >> 6) & 0b10),
((byte1 >> 6) & 0b01) | ((byte2 >> 5) & 0b10),
((byte1 >> 5) & 0b01) | ((byte2 >> 4) & 0b10),
((byte1 >> 4) & 0b01) | ((byte2 >> 3) & 0b10),
((byte1 >> 3) & 0b01) | ((byte2 >> 2) & 0b10),
((byte1 >> 2) & 0b01) | ((byte2 >> 1) & 0b10),
((byte1 >> 1) & 0b01) | (byte2 & 0b10),
(byte1 & 0b01) | ((byte2 << 1) & 0b10),
]
}
fn get_byte_pixels(byte1: u8, byte2: u8, palette: u8) -> [Pixel; 8] { 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 >> 7) & 0b01) | ((byte2 >> 6) & 0b10), palette)),

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@ -67,7 +67,7 @@ pub fn start_eventloop() {
emulator.run(Cycles(70224), pixels.get_frame()); emulator.run(Cycles(70224), pixels.get_frame());
// emulator.draw(pixels.get_frame()); // emulator.draw(pixels.get_frame());
// thread::sleep(time::Duration::from_millis(1000)); thread::sleep(time::Duration::from_millis(10));
window.request_redraw(); window.request_redraw();
}, },
Event::RedrawRequested(_) => { Event::RedrawRequested(_) => {