hdl-js/dist/emulator/hardware/builtin-gates/MipsAlu.js

Hardware definition language (HDL) and Hardware simulator

/**
 * The MIT License (MIT)
 * Copyright (c) 2017-present Dmitry Soshnikov <dmitry.soshnikov@gmail.com>
 */

'use strict';

var _slicedToArray = function () { function sliceIterator(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"]) _i["return"](); } finally { if (_d) throw _e; } } return _arr; } return function (arr, i) { if (Array.isArray(arr)) { return arr; } else if (Symbol.iterator in Object(arr)) { return sliceIterator(arr, i); } else { throw new TypeError("Invalid attempt to destructure non-iterable instance"); } }; }();

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

function _possibleConstructorReturn(self, call) { if (!self) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return call && (typeof call === "object" || typeof call === "function") ? call : self; }

function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }

var BuiltInGate = require('../BuiltInGate');

/**
 * Canonical truth table for the MipsAlu
 */
// prettier-ignore
var TRUTH_TABLE = [
// Add
{ a: 1, b: 1, na: 0, nb: 0, less: 0, cin: 0, op: 2, out: 0, cout: 1, set: 0 }, { a: 1, b: 1, na: 0, nb: 0, less: 0, cin: 1, op: 2, out: 1, cout: 1, set: 0 }, { a: 0, b: 0, na: 0, nb: 0, less: 0, cin: 1, op: 2, out: 1, cout: 0, set: 0 },

// Sub
{ a: 1, b: 1, na: 0, nb: 1, less: 0, cin: 1, op: 2, out: 0, cout: 1, set: 0 },

// And
{ a: 1, b: 1, na: 0, nb: 0, less: 0, cin: 0, op: 0, out: 1, cout: 0, set: 0 },

// Or
{ a: 1, b: 1, na: 0, nb: 0, less: 0, cin: 0, op: 1, out: 1, cout: 0, set: 0 }, { a: 0, b: 1, na: 0, nb: 0, less: 0, cin: 0, op: 1, out: 1, cout: 0, set: 0 }, { a: 0, b: 0, na: 0, nb: 0, less: 0, cin: 0, op: 1, out: 0, cout: 0, set: 0 }];

/**
 * A 1-bit MipsAlu
 */

var MipsAlu = function (_BuiltInGate) {
  _inherits(MipsAlu, _BuiltInGate);

  function MipsAlu() {
    _classCallCheck(this, MipsAlu);

    return _possibleConstructorReturn(this, (MipsAlu.__proto__ || Object.getPrototypeOf(MipsAlu)).apply(this, arguments));
  }

  _createClass(MipsAlu, [{
    key: 'eval',

    /**
     * Logic:
     *
     *   a & b: op = 0
     *   a | b: op = 1
     *   a NOR b => ~a & ~b: op = 0, na = 1, nb = 1
     *
     * Math:
     *
     *   a + b: op = 2
     *   a - b: op = 2, nb = 1, cin = 1
     *   b - a: op = 2, na = 1, cin = 1
     *
     */
    value: function _eval() {
      var _getInputPins$map = this.getInputPins().map(function (pin) {
        return pin.getValue();
      }),
          _getInputPins$map2 = _slicedToArray(_getInputPins$map, 7),
          a = _getInputPins$map2[0],
          b = _getInputPins$map2[1],
          na = _getInputPins$map2[2],
          nb = _getInputPins$map2[3],
          less = _getInputPins$map2[4],
          cin = _getInputPins$map2[5],
          op = _getInputPins$map2[6];

      var A = na ? 1 - a : a;
      var B = nb ? 1 - b : b;

      switch (op) {
        case 0:
          {
            this.getOutputPins()[0].setValue(A & B);
            break;
          }
        case 1:
          {
            this.getOutputPins()[0].setValue(A | B);
            break;
          }
        case 2:
          {
            var sum = A + B + cin;
            this.getOutputPins()[0].setValue(sum % 2);
            this.getOutputPins()[1].setValue(Math.trunc(sum / 2));
            break;
          }
        case 3:
          {
            this.getOutputPins()[0].setValue(less);
            break;
          }
      }
    }
  }]);

  return MipsAlu;
}(BuiltInGate);

/**
 * Specification of the `MipsAlu` gate.
 */


MipsAlu.Spec = {
  name: 'MipsAlu',

  description: '1-bit Mips Alu.\n\nImplements 1-bit MIPS ALU chip.\n\nThe actual ALU operation is controlled by the 2-bit "op" input, which takes the following values:\n\n- 0 - AND\n- 1 - OR\n- 2 - ADD\n- 3 - propagate "less" input\n\nOther operations can be achieved by manipulating different inputs, and the "op" code.\nFor example, to do a subtraction operation "a - b", we need to set cin = 1, and nb = 1.\n\nSetting inputs "na" and "nb" negates the inputs "a" and "b" before performing the operation.\n',
  inputPins: ['a', 'b', 'na', 'nb', 'less', 'cin', { name: 'op', size: 2 }],
  outputPins: ['out', 'cout', 'set'],
  truthTable: TRUTH_TABLE
};

module.exports = MipsAlu;