nes-emu/apu/registers/APUControl.js

A NES emulator

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _registers = require("../../registers");
/** Enables or disables APU channels. */
class APUControl extends _registers.WriteOnlyInMemoryRegister {
  constructor() {
    super();
    this.addReadOnlyField("enablePulse1", 0).addReadOnlyField("enablePulse2", 1).addReadOnlyField("enableTriangle", 2).addReadOnlyField("enableNoise", 3).addReadOnlyField("enableDMC", 4);
  }

  /** When a channel is disabled, it resets its length counters. */
  writeAt(__, byte) {
    const {
      channels
    } = this.context.apu;
    this.setValue(byte);
    const {
      enablePulse1,
      enablePulse2,
      enableTriangle,
      enableNoise,
      enableDMC
    } = this;
    if (!enablePulse1) channels.pulses[0].lengthCounter.counter = 0;
    if (!enablePulse2) channels.pulses[1].lengthCounter.counter = 0;
    if (!enableTriangle) {
      channels.triangle.lengthCounter.counter = 0;
      channels.triangle.linearLengthCounter.counter = 0;
      channels.triangle.linearLengthCounter.reload = 0;
      channels.triangle.linearLengthCounter.reloadFlag = false;
    }
    if (!enableNoise) channels.noise.lengthCounter.counter = 0;
    if (!enableDMC) channels.dmc.stopDPCM();else if (channels.dmc.remainingBytes === 0) channels.dmc.startDPCM();
    this.context.apu.registers.dmc.irqEnable = 0;
  }
}
exports.default = APUControl;