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

A NES emulator

"use strict";

var _createTestContext = _interopRequireDefault(require("../../helpers/createTestContext"));
function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
const should = require("chai").Should();
const ADDRESS = 0x2007;
describe("CPU/PPU registers interaction", () => {
  describe("PPUData", () => {
    let cpu, ppu, memoryBus, register;
    beforeEach(() => {
      ({
        cpu,
        ppu,
        memoryBus
      } = (0, _createTestContext.default)());
      register = ppu.registers.ppuData;
    });
    it("can write VRAM", () => {
      ppu.registers.ppuAddr.address = 0x2016;
      memoryBus.cpu.writeAt(ADDRESS, 24);
      ppu.memory.readAt(0x2016).should.equal(24);
    });
    it("can read VRAM, delayed by 1", () => {
      ppu.memory.writeAt(0x2016, 84);
      ppu.registers.ppuAddr.address = 0x2016;
      cpu.memory.readAt(ADDRESS).should.equal(0);
      ppu.memory.writeAt(0x2016, 92);
      ppu.registers.ppuAddr.address = 0x2016;
      cpu.memory.readAt(ADDRESS).should.equal(84);
      ppu.registers.ppuAddr.address = 0x2016;
      cpu.memory.readAt(ADDRESS).should.equal(92);
    });
    it("can read Palette RAM without delays", () => {
      ppu.memory.writeAt(0x3f10, 123);
      ppu.registers.ppuAddr.address = 0x3f10;
      cpu.memory.readAt(ADDRESS).should.equal(123);
    });
    describe("PPUAddr increment", () => {
      const run = operation => {
        if (operation === "write") memoryBus.cpu.writeAt(ADDRESS, 24);else cpu.memory.readAt(ADDRESS);
      };
      ["write", "read"].forEach(operation => {
        it("".concat(operation, ": increments PPUAddr by 1 if bit 2 of PPUCtrl is 0"), () => {
          ppu.registers.ppuCtrl.setValue(0b00000000);
          ppu.registers.ppuAddr.address = 0x2016;
          run(operation);
          ppu.registers.ppuAddr.address.should.equal(0x2017);
        });
        it("".concat(operation, ": increments PPUAddr by 32 if bit 2 of PPUCtrl is 1"), () => {
          ppu.registers.ppuCtrl.setValue(0b00000100);
          ppu.registers.ppuAddr.address = 0x2016;
          run(operation);
          ppu.registers.ppuAddr.address.should.equal(0x2036);
        });
      });
    });
  });
});