broken-neees/apu/PulseChannel.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 _PulseOscillator = _interopRequireDefault(require("../lib/apu/PulseOscillator"));
var _LengthCounter = _interopRequireDefault(require("./LengthCounter"));
var _VolumeEnvelope = _interopRequireDefault(require("./VolumeEnvelope"));
var _FrequencySweep = _interopRequireDefault(require("./FrequencySweep"));
var _byte = _interopRequireDefault(require("../lib/byte"));
function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
class PulseChannel {
  constructor(apu, id, enableFlagName) {
    this.apu = apu;
    this.id = id;
    this.enableFlagName = enableFlagName;
    this.timer = 0;
    this.registers = this.apu.registers.pulses[this.id];
    this.oscillator = new _PulseOscillator.default();
    this.lengthCounter = new _LengthCounter.default();
    this.volumeEnvelope = new _VolumeEnvelope.default();
    this.frequencySweep = new _FrequencySweep.default(this);
    this.outputSample = 0;

    // [!!!]
    this.random = 200;
  }
  sample() {
    if (!this.isEnabled() || !this.lengthCounter.isActive() || this.frequencySweep.mute) return this.outputSample;

    // from nesdev: f = fCPU / (16 * (t + 1))
    this.oscillator.frequency = 1789773 / (16 * (this.timer + 1));
    this.oscillator.dutyCycle = this.registers.control.dutyCycleId;
    this.oscillator.volume = this.registers.control.constantVolume ? this.registers.control.volumeOrEnvelopePeriod : this.volumeEnvelope.volume;

    // [!!!]
    if (!this.apu.cpu.unbroken) this.oscillator.frequency = Math.abs(1789773 / (16 * (this.timer + 1)) - this.random);
    this.outputSample = this.oscillator.sample();
    return this.outputSample;
  }
  updateTimer() {
    this.timer = _byte.default.buildU16(this.registers.timerHighLCL.timerHigh, this.registers.timerLow.value);
  }
  step() {
    this.frequencySweep.muteIfNeeded();
    if (!this.registers.sweep.enabledFlag) this.updateTimer();
  }
  quarterFrame() {
    this.volumeEnvelope.clock(this.registers.control.volumeOrEnvelopePeriod, this.registers.control.envelopeLoopOrLengthCounterHalt);
  }
  halfFrame() {
    this.lengthCounter.clock(this.isEnabled(), this.registers.control.envelopeLoopOrLengthCounterHalt);
    this.frequencySweep.clock();
  }
  isEnabled() {
    return !!this.apu.registers.apuControl[this.enableFlagName];
  }
}
exports.default = PulseChannel;