// WAFER JS Loader - generated by wafer build --js
// Loads and runs test_js.wasm in the browser.

const WAFER = (() => {
  const CELL_SIZE = 4;
  const DATA_STACK_TOP = 0x1540;
  const SYSVAR_BASE = 0x0004;
  let outputCallback = (s) => {
    const el = document.getElementById('output');
    if (el) el.textContent += s;
    else console.log(s);
  };

  async function run(opts) {
    if (opts && opts.output) outputCallback = opts.output;

    const memory = new WebAssembly.Memory({ initial: 16 });
    const dsp = new WebAssembly.Global({ value: 'i32', mutable: true }, 5440);
    const rsp = new WebAssembly.Global({ value: 'i32', mutable: true }, 9536);
    const fsp = new WebAssembly.Global({ value: 'i32', mutable: true }, 11584);
    const table = new WebAssembly.Table({ element: 'anyfunc', initial: 256 });

    function emit(code) {
      outputCallback(String.fromCharCode(code));
    }

    const importObject = {
      env: { emit, memory, dsp, rsp, fsp, table }
    };

    // Register host functions
    const view = () => new DataView(memory.buffer);
    const pop = () => {
      const sp = dsp.value;
      const v = view().getInt32(sp, true);
      dsp.value = sp + CELL_SIZE;
      return v;
    };
    const push = (v) => {
      const sp = dsp.value - CELL_SIZE;
      view().setInt32(sp, v, true);
      dsp.value = sp;
    };

    table.set(84, new WebAssembly.Function({parameters:[], results:[]}, () => {
      const n = pop();
      const base = view().getUint32(SYSVAR_BASE, true);
      outputCallback((base === 16 ? n.toString(16).toUpperCase() : n.toString()) + ' ');
    }));

    const response = await fetch('test_js.wasm');
    const bytes = await response.arrayBuffer();
    const { instance } = await WebAssembly.instantiate(bytes, importObject);

    if (instance.exports._start) {
      instance.exports._start();
    }

    return instance;
  }

  return { run };
})();