nes-emu/cpu/addressings/relative.js

A NES emulator

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _helpers = require("../../helpers");
var _getValue = _interopRequireDefault(require("./_getValue"));
function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
/**
 * "Relative" addressing mode.
 *
 * The parameter is a signed relative offset from the following instruction.
 */
var _default = exports.default = {
  id: "RELATIVE",
  parameterSize: 1,
  getAddress: (_ref, offset, canTakeExtraCycles) => {
    let {
      cpu
    } = _ref;
    const address = cpu.pc.value;
    const newAddress = address + _helpers.Byte.toNumber(offset);
    const pageCrossed = _helpers.Byte.highPartOf(address) !== _helpers.Byte.highPartOf(newAddress);
    if (pageCrossed && canTakeExtraCycles) cpu.extraCycles += 2;
    return _helpers.Byte.force16Bit(newAddress);
  },
  getValue: _getValue.default
};