Crate padme_core

Expand description

§Padme

padme_core is a gameboy emulator engine that can be used to create a gameboy emulator on any platform. It is possible to use padme to build an emulator on any platform, so it supports no_std environments. It’s especially a great fit for web assembly or embedded devices where you cannot always rely on dynamic memory allocation or threads. Although, for simplicity, most examples and tests use the std crate.

For now, it’s not planned to support gameboy color or gameboy advance, but maybe later.

§How to build an emulator

use padme_core::{AudioSpeaker, Button, Pixel, Rom, Screen, SerialOutput, System};

struct MyScreen {
   // ... your framebuffer implementation
}

impl Screen for MyScreen {
    fn set_pixel(&mut self, pixel: &Pixel, x: u8, y: u8) {
        // add pixel to your framebuffer
    }
    fn update(&mut self) {
        // a frame has been pushed
        // this is called during a VBlank
    }
}

struct MySpeaker {
    // ... your audio buffer implementation
}

impl AudioSpeaker for MySpeaker {
    fn set_samples(&mut self, left: f32, right: f32) {
        // add samples for left and right channels
    }
}

struct MySerialConsole {
}

impl SerialOutput for MySerialConsole {
    fn putchar(&mut self, ch: u8) {
        // a byte has been transmitted
    }
}

// Loads a game, most commonly, it is retrieved from a file
// let bin: Vec<u8> = std::fs::read("some_game.gb").expect("could not find game");
let mut rom = Rom::load(&mut bin[..]).unwrap();
let mut emulator = System::new(rom, MyScreen {}, MySerialConsole {}, MySpeaker {});
// Set the number of frame per seconds
// This also sets the number of cycles needed per frame given the fixed CPU clock frequency
emulator.set_frame_rate(60);

while running {
    let t0 = std::time::Instant::now();
    emulator.update_frame();
    emulator.set_button(Button::A, a_pressed);
    emulator.set_button(Button::B, b_pressed);
    emulator.set_button(Button::Start, start_pressed);
    emulator.set_button(Button::Select, select_pressed);
    emulator.set_button(Button::Up, up_pressed);
    emulator.set_button(Button::Down, down_pressed);
    emulator.set_button(Button::Left, left_pressed);
    emulator.set_button(Button::Right, right_pressed);
    // here we need to sleep for the remaining time
    let frame_time = t0.elapsed();
    let min_frame_time = emulator.min_frame_time();
    if frame_time < min_frame_time {
        std::thread::sleep(min_frame_time - frame_time);
    }
}