nes-emu/controller/ControllerPort.js

A NES emulator

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _registers = require("../registers");
var _constants = _interopRequireDefault(require("../constants"));
var _helpers = require("../helpers");
function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
/**
 * Controller Port Register
 *
 * If the "strobe" flag is active, reads return the current state of the A button.
 * If not, reads return the current state of [A, B, Select, Start, Up, Down, Left, Right] in a loop.
 */
class ControllerPort extends _registers.InMemoryRegister {
  constructor() {
    super();
    this.cursor = 0;
  }

  /** Returns the strobe flag. */
  get strobe() {
    throw new Error("not_implemented");
  }

  /** Reads the current buton state, and updates the cursor if the strobe flag is on. */
  readAt() {
    if (this.cursor >= _constants.default.BUTTONS) return 1;
    const isPressed = _helpers.Byte.getBit(this.value, this.cursor);
    if (!this.strobe) this.cursor++;
    return isPressed;
  }
}
exports.default = ControllerPort;