broken-neees/apu/NoiseChannel.js

A really broken NEEES emulator that introduces glitches and random bugs on purpose!

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _LengthCounter = _interopRequireDefault(require("./LengthCounter"));
var _VolumeEnvelope = _interopRequireDefault(require("./VolumeEnvelope"));
var _noisePeriods = _interopRequireDefault(require("../lib/apu/noisePeriods"));
var _byte = _interopRequireDefault(require("../lib/byte"));
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
function _typeof(obj) { "@babel/helpers - typeof"; return _typeof = "function" == typeof Symbol && "symbol" == typeof Symbol.iterator ? function (obj) { return typeof obj; } : function (obj) { return obj && "function" == typeof Symbol && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }, _typeof(obj); }
function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a 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, _toPropertyKey(descriptor.key), descriptor); } }
function _createClass(Constructor, protoProps, staticProps) { if (protoProps) _defineProperties(Constructor.prototype, protoProps); if (staticProps) _defineProperties(Constructor, staticProps); Object.defineProperty(Constructor, "prototype", { writable: false }); return Constructor; }
function _toPropertyKey(arg) { var key = _toPrimitive(arg, "string"); return _typeof(key) === "symbol" ? key : String(key); }
function _toPrimitive(input, hint) { if (_typeof(input) !== "object" || input === null) return input; var prim = input[Symbol.toPrimitive]; if (prim !== undefined) { var res = prim.call(input, hint || "default"); if (_typeof(res) !== "object") return res; throw new TypeError("@@toPrimitive must return a primitive value."); } return (hint === "string" ? String : Number)(input); }
var NoiseChannel = /*#__PURE__*/function () {
  function NoiseChannel(apu) {
    _classCallCheck(this, NoiseChannel);
    this.apu = apu;
    this.registers = this.apu.registers.noise;
    this.lengthCounter = new _LengthCounter.default();
    this.volumeEnvelope = new _VolumeEnvelope.default();
    this.shift = 1; // (the shift register is 15 bits wide)
    this.dividerCount = 0;
  }
  _createClass(NoiseChannel, [{
    key: "sample",
    value: function sample() {
      if (!this.isEnabled() || !this.lengthCounter.isActive() || this.isMuted()) return 0;
      return this.registers.control.constantVolume ? this.registers.control.volumeOrEnvelopePeriod : this.volumeEnvelope.volume;
    }
  }, {
    key: "step",
    value: function step() {
      this.dividerCount++;
      if (this.dividerCount >= _noisePeriods.default[this.registers.form.periodId]) this.dividerCount = 0;else return;
      var bitPosition = this.registers.form.mode ? 6 : 1;
      var bit = _byte.default.getBit(this.shift, bitPosition);
      var feedback = _byte.default.getBit(this.shift, 0) ^ bit;
      this.shift = this.shift >> 1 | feedback << 14;
    }
  }, {
    key: "quarterFrame",
    value: function quarterFrame() {
      this.volumeEnvelope.clock(this.registers.control.volumeOrEnvelopePeriod, this.registers.control.envelopeLoopOrLengthCounterHalt);
    }
  }, {
    key: "halfFrame",
    value: function halfFrame() {
      this.lengthCounter.clock(this.isEnabled(), this.registers.control.envelopeLoopOrLengthCounterHalt);
    }
  }, {
    key: "isEnabled",
    value: function isEnabled() {
      return !!this.apu.registers.apuControl.enableNoise;
    }
  }, {
    key: "isMuted",
    value: function isMuted() {
      return !_byte.default.getBit(this.shift, 0);
    }
  }]);
  return NoiseChannel;
}();
exports.default = NoiseChannel;