gb/src/main.rs

134 lines
4.3 KiB
Rust

use anyhow::{anyhow, Result};
use clap::{crate_authors, crate_description, crate_name, crate_version, App, Arg};
use gb::LR35902_CLOCK_SPEED;
use gb::{Cycle, LR35902};
use pixels::{Pixels, SurfaceTexture};
use std::time::{Duration, Instant};
use winit::dpi::LogicalSize;
use winit::event::{Event, VirtualKeyCode};
use winit::event_loop::{ControlFlow, EventLoop};
use winit::window::{Window, WindowBuilder};
use winit_input_helper::WinitInputHelper;
// 160 x 144
const GB_WIDTH: u32 = 160;
const GB_HEIGHT: u32 = 144;
const SCALE: f64 = 5.0;
const LR35902_CYCLE_TIME: f64 = 1.0f64 / LR35902_CLOCK_SPEED as f64;
const CYCLES_IN_FRAME: Cycle = Cycle::new(70224);
fn main() -> Result<()> {
let app = App::new(crate_name!())
.version(crate_version!())
.author(crate_authors!())
.about(crate_description!());
let m = app
.arg(
Arg::with_name("rom")
.value_name("ROM_FILE")
.takes_value(true)
.required(true)
.index(1)
.help("Path to the Game ROM"),
)
.arg(
Arg::with_name("boot")
.short("b")
.long("boot")
.value_name("FILE")
.takes_value(true)
.help("Path to Boot ROM"),
)
.get_matches();
let mut game_boy = match m.value_of("boot") {
Some(path) => LR35902::boot_new(path).expect("Failed to load boot ROM"),
None => LR35902::new(),
};
// This is a required value so if we program gets here,
// a string **will** have been provided to the rom argument
let rom_path = m
.value_of("rom")
.expect("ROM Path not provided despite it being a required argument");
game_boy
.load_cartridge(rom_path)
.expect("Failed to load ROM");
let default_title = "DMG-01 Emulator";
let cartridge_title = game_boy.rom_title().unwrap_or(&default_title);
// Initialize GUI
let event_loop = EventLoop::new();
let mut input = WinitInputHelper::new();
let window = create_window(&event_loop, cartridge_title)?;
let mut pixels = create_pixels(&window)?;
let mut now = Instant::now();
let mut cycles_in_frame: Cycle = Default::default();
event_loop.run(move |event, _, control_flow| {
if let Event::RedrawRequested(_) = event {
if pixels
.render()
.map_err(|e| anyhow!("pixels.render() failed: {}", e))
.is_err()
{
*control_flow = ControlFlow::Exit;
return;
}
}
if input.update(&event) {
if input.key_pressed(VirtualKeyCode::Escape) || input.quit() {
*control_flow = ControlFlow::Exit;
return;
}
if let Some(size) = input.window_resized() {
pixels.resize(size.width, size.height);
}
// Emulate Game Boy
let delta = now.elapsed().subsec_nanos();
now = Instant::now();
let cycle_time = Duration::from_secs_f64(LR35902_CYCLE_TIME).subsec_nanos();
let pending_cycles = Cycle::new(delta / cycle_time);
let mut elapsed_cycles: Cycle = Default::default();
while elapsed_cycles <= pending_cycles {
elapsed_cycles += game_boy.step();
}
cycles_in_frame += elapsed_cycles;
if cycles_in_frame >= CYCLES_IN_FRAME {
let ppu = game_boy.get_ppu();
let frame = pixels.get_frame();
ppu.copy_to_gui(frame);
window.request_redraw();
cycles_in_frame = Default::default()
}
}
});
}
fn create_window(event_loop: &EventLoop<()>, title: &str) -> Result<Window> {
let size = LogicalSize::new((GB_WIDTH as f64) * SCALE, (GB_HEIGHT as f64) * SCALE);
Ok(WindowBuilder::new()
.with_title(title)
.with_inner_size(size)
.with_min_inner_size(size)
.build(&event_loop)?)
}
fn create_pixels(window: &Window) -> Result<Pixels<Window>> {
let window_size = window.inner_size();
let surface_texture = SurfaceTexture::new(window_size.width, window_size.height, window);
Ok(Pixels::new(GB_WIDTH, GB_HEIGHT, surface_texture)?)
}