nes-emu/ppu/registers/OAMDMA.spec.js

A NES emulator

"use strict";

var _createTestContext = _interopRequireDefault(require("../../helpers/createTestContext"));
var _helpers = require("../../helpers");
function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
const should = require("chai").Should();
const ADDRESS = 0x4014;
describe("CPU/PPU registers interaction", () => {
  describe("OAMDMA", () => {
    let cpu, ppu, memory, register;
    beforeEach(() => {
      ({
        cpu,
        ppu,
        memory
      } = (0, _createTestContext.default)());
      register = ppu.registers.oamDma;
    });
    it("is write-only", () => {
      register.setValue(123);
      memory.readAt(ADDRESS).should.equal(0);
    });
    it("copies the whole page to OAM and add 514 cycles", () => {
      for (let i = 0; i < 256; i++) memory.writeAt(_helpers.Byte.to16Bit(0x06, i), 255 - i);
      memory.writeAt(ADDRESS, 0x06);
      for (let i = 0; i < 256; i++) ppu.oamRam[i].should.equal(255 - i);
      cpu.extraCycles.should.equal(514);
    });
  });
});