nes-emu/cpu/CPUMemoryMap.spec.js

A NES emulator

"use strict";

var _registers = require("./registers");
var _constants = _interopRequireDefault(require("../constants"));
var _createTestContext = _interopRequireDefault(require("../helpers/createTestContext"));
var _lodash = _interopRequireDefault(require("lodash"));
function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
const should = require("chai").Should();
const RAM_MIRROR_ADDRESS = 0x0800;
const MAPPER_SIZE = 0xbfe0;
const KB = 1024;
describe("memory", () => {
  describe("CPUMemoryMap", () => {
    let memory;
    beforeEach(() => {
      ({
        memory
      } = (0, _createTestContext.default)());
    });
    it("stores the start address of each chunk", () => {
      _lodash.default.last(memory.chunks).$memoryStartAddress.should.equal(_constants.default.CPU_MAPPER_START_ADDRESS);
    });
    it("stores the memory size", () => {
      memory.memorySize.should.equal(64 * KB);
    });
    it("can write in the right chunk", () => {
      memory.writeAt(RAM_MIRROR_ADDRESS + 3, 123);
      memory.chunks[1].readAt(3).should.equal(123);
    });
    it("can read from the right chunk", () => {
      memory.chunks[1].writeAt(3, 123);
      memory.readAt(RAM_MIRROR_ADDRESS + 3).should.equal(123);
    });
    [123, 0].forEach(value => {
      it("can accept a register as address (containing ".concat(value, " as value)"), () => {
        const register = new _registers.Register8Bit(value);
        memory.writeAt(register, 250);
        register.value.should.equal(250);
      });
    });
    it("can read and write RAM's mirror", () => {
      memory.writeAt(0, 129);
      memory.readAt(0x1800).should.equal(129);
      memory.writeAt(0x1801, 201);
      memory.readAt(1).should.equal(201);
    });
    it("can read and write numbers in Little Endian", () => {
      memory.writeAt(0, 0x20);
      memory.writeAt(1, 0xff);
      memory.write2BytesAt(2, 0xfe30);
      memory.readBytesAt(0, 1).should.equal(0x20);
      memory.readBytesAt(1, 1).should.equal(0xff);
      memory.readBytesAt(0, 2).should.equal(0xff20);
      memory.read2BytesAt(0).should.equal(0xff20);
      memory.read2BytesAt(2).should.equal(0xfe30);
    });
    it("throws an exception when the address is out of bounds", () => {
      (() => memory.readAt(_constants.default.CPU_MAPPER_START_ADDRESS + MAPPER_SIZE)).should.throw("Unreachable address: 0x10000.");
    });
  });
});