nes-emu/cpu/CPUMemoryMap.js

A NES emulator

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _memory = require("../memory");
var _registers = require("../registers");
var _helpers = require("../helpers");
/** The CPU memory map. Addess space size: 64KB. */
class CPUMemoryMap {
  constructor() {
    _helpers.WithContext.apply(this);
    _memory.WithCompositeMemory.apply(this);
  }

  /** When a context is loaded. */
  onLoad(_ref) {
    let {
      ppu,
      apu,
      mapper,
      controllers
    } = _ref;
    this.ram = new _memory.MemoryChunk(0x0800);
    const ramMirror = new _memory.MemoryMirror(this.ram, 0x1800);
    const ppuRegisters = ppu.registers.toMemory();
    const ppuRegistersMirror = new _memory.MemoryMirror(ppuRegisters, 0x1ff8);
    const apuRegisters = apu.registers.toMemory();
    const port2AndFrameCounter = new _registers.MixedInMemoryRegister(controllers[1].port, apu.registers.apuFrameCounter);
    const cpuTestModeRegisters = new _memory.MemoryPadding(0x0008);
    this.defineChunks([
    //                        Address range  Size     Device
    this.ram,
    //              $0000-$07FF    $0800    2KB internal RAM
    ramMirror,
    //             $0800-$1FFF    $1800    Mirrors of $0000-$07FF
    ppuRegisters,
    //          $2000-$2007    $0008    NES PPU registers
    ppuRegistersMirror,
    //    $2008-$3FFF    $1FF8    Mirrors of $2000-$2007 (repeats every 8 bytes)
    apuRegisters,
    //          $4000-$4013    $0014    NES APU registers
    ppu.registers.oamDma,
    //  $4014-$4014    $0001    PPU's OAM DMA register
    apu.registers.apuMain,
    // $4015-$4015    $0001    APU status/control register
    controllers[0].port,
    //   $4016-$4016    $0001    Controller port 1
    port2AndFrameCounter,
    //  $4017-$4017    $0001    Controller port 2 and APU frame counter
    cpuTestModeRegisters,
    //  $4018-$401F    $0008    APU and I/O functionality that is normally disabled
    mapper.segments.cpu //    $4020-$FFFF    $BFE0    Cartridge space: PRG ROM, PRG RAM, and mapper registers
    ]);
  }

  /** Reads a `byte` from `address`, which can be a register or a memory address. */
  readAt(address) {
    return address.value != null ? address.value : _memory.WithCompositeMemory.readAt.call(this, address);
  }

  /** Writes a `byte` to `address`, which can be a register or a memory address. */
  writeAt(address, byte) {
    if (address.value != null) address.value = byte;else _memory.WithCompositeMemory.writeAt.call(this, address, byte);
  }

  /** Returns a snapshot of the current state. */
  getSaveState() {
    const {
      ppu,
      apu
    } = this.context;
    return {
      ram: Array.from(this.ram.bytes),
      ppuRegisters: ppu.registers.toMemory().chunks.map(it => it.value),
      apuRegisters: apu.registers.toMemory().chunks.map(it => it.value),
      apuControl: apu.registers.apuControl.value,
      apuFrameCounter: apu.registers.apuFrameCounter.value
    };
  }

  /** Restores state from a snapshot. */
  setSaveState(saveState) {
    const {
      ppu,
      apu
    } = this.context;
    this.ram.bytes.set(saveState.ram);
    ppu.registers.toMemory().chunks.forEach((chunk, i) => {
      chunk.setValue && chunk.setValue(saveState.ppuRegisters[i]);
    });
    apu.registers.toMemory().chunks.forEach((chunk, i) => {
      chunk.setValue && chunk.setValue(saveState.apuRegisters[i]);
    });
    apu.registers.apuControl.setValue(saveState.apuControl);
    apu.registers.apuFrameCounter.setValue(saveState.apuFrameCounter);
  }
}
exports.default = CPUMemoryMap;