Crate oxid8_core 

Oxid-8 Core

oxid8_core is an interpreter core for the Chip-8 programming language, developed by Joseph Weisbecker in the mid-1970s for making games on the COSMAC VIP and Telmac 1800.

This is the core interpreter library for Oxid8. So that developers can create their own renderers on top of this library crate.

Getting Started

use oxid8_core::Oxid8;
use std::time::{Duration, Instant};

#[derive(Default)]
struct State {
    should_exit: bool,
    last_frame: Option<Instant>,
}

#[derive(Default)]
struct Emu {
    state: State,
    core: Oxid8,
}

fn main() -> std::io::Result<()> {
    let mut emu = Emu::default();
    emu.core.load_font();
    emu.core.load_rom("rom_path")?;

    while !emu.state.should_exit {
        let time = Instant::now();

        // TODO: Poll and Handle Events.

        if let Some(last_frame) = emu.state.last_frame {
            if time.duration_since(last_frame) >= Duration::from_millis(16) {
                if let Err(err) = emu.core.next_frame() {
                    panic!("{err}");
                }

                // TODO: Draw current frame.

                emu.state.last_frame = Some(time);
            }

            if emu.core.sound() {
                // TODO: Beep!
            }

        } else {
            emu.state.last_frame = Some(Instant::now());
        }
    }

    Ok(())
}

WASM Compatibility

# Cargo.toml

[dependencies]
web-time = "1.1.0"

[target.'cfg(target_arch = "wasm32")'.dependencies]
getrandom = { version = "0.3", features = ["wasm_js"] }

# config.toml

[target.'cfg(target_arch = "wasm32")']
rustflags = ["--cfg", 'getrandom_backend="wasm_js"']

Frame Time

You should generate frames at 60Hz or roughly 16ms if not relying on vsync. std::time::{Instant, Duration} panic in the web so use the web-time crate when compiling to web assembly.

Structs

Oxid8

Oxid8 Core

Constants

CPU_TICK

Standard CPU tick rate set to 700Hz. This value is not used internally. Run a CPU cycle this often.

SCREEN_AREA

Virtual screen area (2048 pixels).

SCREEN_HEIGHT

Virtual screen height (32 pixels).

SCREEN_WIDTH

Virtual screen width (64 pixels).

TIMER_TICK

Standard TIMER tick rate set to 60Hz. This value is not used internally. Decrement the timers and refresh the display this often.