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PPU timings

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This commit is contained in:
Franco Colmenarez 2021-10-28 19:38:30 -05:00
parent 6ad3f9f29b
commit 7f9fdc9935
5 changed files with 117 additions and 32 deletions
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9
src/bus.rs
View File

@ -40,7 +40,8 @@ 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("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/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()) {
@ -65,11 +66,7 @@ impl Bus {
if BANK_ZERO.in_range(address) || BANK_SWITCHABLE.in_range(address) {
return self.game_rom.read(address);
} else if IO_REGISTERS.in_range(address) {
return match address {
0xFF44 => 0x90,
0xFF4D => 0xFF,
_ => self.data[address as usize],
}
return self.data[address as usize];
}
self.data[address as usize]
}

2
src/cpu.rs
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@ -806,8 +806,6 @@ pub enum Opcode {
PrefixCB(Box<Opcode>),
IllegalInstruction,
}
// Frequency un Hz
const FREQUENCY: f64 = 4194.304;
// Store cycles in M
#[derive(Debug, Copy, Clone)]

5
src/emulator.rs
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@ -20,8 +20,8 @@ impl Emulator {
}
pub fn draw(&mut self, frame: &mut [u8]) {
self.ppu.draw_background(&self.bus);
let ppu_frame = self.ppu.get_rgba_frame(&self.bus);
// self.ppu.draw_background(&mut self.bus);
let ppu_frame = self.ppu.get_rgba_frame();
for (i, pixel) in frame.chunks_exact_mut(4).enumerate() {
pixel.copy_from_slice(&ppu_frame[i]);
}
@ -30,6 +30,7 @@ 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);
}
}

128
src/ppu.rs
View File

@ -6,7 +6,6 @@ use crate::utils::{
};
use crate::bus::{Bus, AddressRange, BANK_ZERO, VIDEO_RAM};
use crate::cpu::{Cycles};
use rand::Rng;
#[derive(Debug, Copy, Clone)]
enum Pixel {
@ -46,8 +45,10 @@ pub enum LCDStatus {
ModeFlag(LCDStatusModeFlag),
}
pub const WIDTH: u32 = 160;
pub const HEIGHT: u32 = 144;
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 FRAME_BUFFER_LENGTH: u32 = WIDTH * HEIGHT;
const LCD_CONTROL_ADDRESS: u16 = 0xFF40;
@ -74,10 +75,60 @@ impl PPU {
pub fn new() -> Self {
Self {
cycles: Cycles(0),
rgba_frame: [[0, 0, 0xFF, 0]; FRAME_BUFFER_LENGTH as usize],
rgba_frame: [[0xFF, 0xFF, 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 {
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::VBlank), true);
} else {
if self.cycles.0 <= 80 {
// Mode 2 OAM scan
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::SearchingOAM), true);
} else if self.cycles.0 <= 80 + 172 {
// Mode 3 drawing pixel line. This could also last 289 cycles
if !PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD)) {
self.draw_line(bus);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD), true);
}
} else if self.cycles.0 <= 80 + 172 + 204 {
// 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);
}
}
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)
}
@ -158,26 +209,46 @@ impl PPU {
bus.write(LCD_STATUS_ADDRESS, byte);
}
fn get_pixel(two_bit_pixel: u8) -> Pixel {
match two_bit_pixel {
0x00 => Pixel::White,
0x01 => Pixel::Light,
0x10 => Pixel::Dark,
0x11 => Pixel::Black,
_ => Pixel::Black,
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_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: &mut Bus) {
let mut lcd_y: u8 = 0;
PPU::set_lcd_y(bus, lcd_y);
while lcd_y < 144 {
self.draw_line(bus);
lcd_y += 1;
PPU::set_lcd_y(bus, lcd_y);
}
}
pub fn draw_background(&mut self, bus: &Bus) {
/* pub fn draw_background_old(&mut self, bus: &Bus) {
let mut idx = 0;
// let mut tile_line: u16 = 0;
let mut lcd_y: u8 = 0;
@ -207,6 +278,25 @@ impl PPU {
lcd_y += 1;
// tile_line += 2;
}
} */
fn get_pixel(two_bit_pixel: u8) -> Pixel {
match two_bit_pixel {
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],
}
}
fn get_byte_pixels(byte1: u8, byte2: u8) -> [Pixel; 8] {
@ -222,7 +312,7 @@ impl PPU {
pixels
}
pub fn get_rgba_frame(&self, bus: &Bus) -> &[[u8; 4]; FRAME_BUFFER_LENGTH as usize] {
pub fn get_rgba_frame(&self) -> &[[u8; 4]; FRAME_BUFFER_LENGTH as usize] {
&self.rgba_frame
}
}

3
src/render.rs
View File

@ -38,7 +38,6 @@ 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) {
@ -66,7 +65,7 @@ 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(_) => {