nes-emu/apu/registers/PulseLCLTimerHigh.js

A NES emulator

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _registers = require("../../registers");
var _constants = require("../constants");
/** Sets the high 3 bits of a Pulse channel's timer and its length counter. */
class PulseLCLTimerHigh extends _registers.WriteOnlyInMemoryRegister {
  constructor(id) {
    super();
    this.id = id;
    this.addReadOnlyField("timerHigh", 0, 3).addReadOnlyField("lengthCounterLoad", 3, 5);
  }

  /** Updates timer value, length counter, and volume envelope's start flag. */
  writeAt(__, byte) {
    this.setValue(byte);
    const channel = this.context.apu.channels.pulses[this.id];
    channel.updateTimer();
    channel.lengthCounter.counter = _constants.lengthTable[this.lengthCounterLoad];
    channel.volumeEnvelope.startFlag = true;
  }
}
exports.default = PulseLCLTimerHigh;