ToyCPU-4bit/toyvm/src/main.rs

use clap::Parser;
use std::{error::Error, fs::File, io::Read, path::PathBuf};
use toy_cpu_4bit::cpu::Cpu;

/// ToyCPU-4bit Virtual Machine
#[derive(Parser)]
#[clap(version, about, long_about = None)]
struct Args {
    /// Visualize every CPU tick
    #[clap(short, long)]
    trace: bool,
    /// Path to 256-byte file with code for CPU
    code: PathBuf,
}

fn read_code(path: PathBuf) -> Result<[u8; 256], Box<dyn Error>> {
    let mut file = File::open(path)?;
    match file.metadata()?.len() {
        x if x != 256 => {
            Err(format!("Wrong code file size, expected: 256, provided: {}", x).into())
        }
        _ => {
            let mut buf = [0u8; 256];
            file.read_exact(&mut buf)?;
            Ok(buf)
        }
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    let args = Args::parse();
    let code = read_code(args.code)?;
    let mut cpu = Cpu::new(&code);
    loop {
        if cpu.step() {
            break;
        }
        if args.trace {
            cpu.visualize();
        }
    }
    Ok(())
}