example.js

/* Small example driver program for compiling/running programs */
const fs = require("fs");
const { exec } = require("child_process");
var args = process.argv.slice(2);

/**  We execute this with the path of the file we want to compile */
const compile_cmd = "sh compile.sh";

/**  Memory that will be imported in WASM runtime */
const memory = new WebAssembly.Memory({ initial: 1 });

/** Utility for parsing strings out of C0's memory */
const c0_parse_str = (address) => {
  const bytes = new Uint8Array(memory.buffer.slice(address | 0));
  var i = 0;
  var msg = "";
  while (i < bytes.length && bytes[i] !== undefined && bytes[i] !== 0) {
    msg += String.fromCharCode(bytes[i]);
    i += 1;
  }
  return msg;
};

/** Required imports */
const imports = {
  c0deine: {
    memory: memory,
    result: (res) => {
      console.log(res | 0);
    },
    abort: (sig) => {
      console.log("abort: " + (sig | 0));
    },
    error: (str) => {
      console.log("error:  " + c0_parse_str(str));
    },
    debug: (lbl) => {
      console.log("debug:  entered label " + lbl);
      setTimeout(() => {
        return 0;
      }, 0);
    },
  },
  conio: {
    print: (str) => {
      process.stdout.write(c0_parse_str(str));
    },
    println: (str) => {
      process.stdout.write(c0_parse_str(str) + "\n");
    },
    flush: () => {
      process.stdout.flush();
      setTimeout(() => {}, 0);
    },
    eof: () => {
      console.log("TODO: eof unimplemented!");
    },
    readline: () => {
      console.log("TODO: readline unimplemented!");
    },
  },
};

/** Drivers to compile and evaluate programs */
function compile(filename, exe, next) {
  exec(compile_cmd + " " + filename, (error, stdout, stderr) => {
    if (error !== null) {
      console.log(stdout);
      console.log(stderr);
      return next();
    }
    return exe();
  });
}

function run(filename, imports) {
  const bytes = fs.readFileSync(filename + ".wasm");
  const wasm = new WebAssembly.Module(bytes);

  try {
    const instance = new WebAssembly.Instance(wasm, imports);
  } catch (e) {
    console.log(e + "");
  }
}

if (!fs.existsSync(args[0])) {
  console.log("Couldn't find file: " + args[0] + "\n");
} else if (fs.lstatSync(args[0]).isFile()) {
  const filename = args[0];
  compile(
    filename,
    () => {
      run(filename, imports);
    },
    () => {
      console.log("Compilation failed.");
    }
  );
}