hdl-js/dist/emulator/hardware/builtin-gates/RAM4K.js

Hardware definition language (HDL) and Hardware simulator

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

'use strict';

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 colors = require('colors');
var RAM = require('./RAM');

var _require = require('../../../util/numbers'),
    int16Table = _require.int16Table;

/**
 * Canonical truth table for the `RAM4K` gate.
 */


var TRUTH_TABLE = int16Table([{
  $clock: -0,
  in: 0,
  load: 0,
  address: 0,
  out: 0
}, {
  $clock: +0,
  in: 21,
  load: 1,
  address: 0,
  out: 0
}, {
  $clock: -1,
  in: 1,
  load: 0,
  address: 0,
  out: 21
}, {
  $clock: +1,
  in: 21,
  load: 0,
  address: 0,
  out: 21
}, {
  $clock: -2,
  in: 21,
  load: 0,
  address: 0,
  out: 21
}, {
  $clock: +2,
  in: 53781,
  load: 1,
  address: 2,
  out: 0
}, {
  $clock: -3,
  in: 53781,
  load: 0,
  address: 2,
  out: 53781
}, {
  $clock: +3,
  in: 65535,
  load: 1,
  address: 4095,
  out: 0
}, {
  $clock: -4,
  in: 0,
  load: 1,
  address: 4095,
  out: 65535
}, {
  $clock: +4,
  in: 0,
  load: 1,
  address: 4095,
  out: 65535
}, {
  $clock: -5,
  in: 0,
  load: 0,
  address: 4095,
  out: 0
}]);

/**
 * RAM chip of 4K 16-bit registers.
 *
 * The output is the value stored at the memory location specified by address.
 * If load=1, loads the input into the memory location specified by address.
 *
 * Abstract:
 *
 *  IN in[16], load, address[12];
 *  OUT out[16];
 *
 *  DMux8Way(in=load, sel=address, ...);
 *  RAM512(in=in, load=l1, address=address[0..8], out=r1);
    RAM512(in=in, load=l2, address=address[0..8], out=r2);
 *  ...
 *  Mux8Way16(...);
 */

var RAM4K = function (_RAM) {
  _inherits(RAM4K, _RAM);

  function RAM4K(options) {
    _classCallCheck(this, RAM4K);

    return _possibleConstructorReturn(this, (RAM4K.__proto__ || Object.getPrototypeOf(RAM4K)).call(this, Object.assign({ size: 4 * 1024 }, options)));
  }

  return RAM4K;
}(RAM);

/**
 * Specification of the `RAM4K` gate.
 */


RAM4K.Spec = {
  name: 'RAM4K',

  description: ['Memory chip consisting of 4K 16-bit registers.', '', 'If load[t]=1 then out[t+1] = in[t] else out does not change.', '', 'Clock rising edge updates the value from the input by the address,', 'if the `load` is set; otherwise, preserves the state.', '', '  ' + colors.bold('↗') + ' : value[address] = load ? in : value[address]', '', 'Clock falling edge propagates the value at the address to the output:', '', '  ' + colors.bold('↘') + ' : out = value[address]'].join('\n'),

  inputPins: [{ name: 'in', size: 16 }, { name: 'load', size: 1 }, { name: 'address', size: 12 }],

  outputPins: [{ name: 'out', size: 16 }],

  truthTable: TRUTH_TABLE
};

module.exports = RAM4K;