nes-emu/ppu/registers/OAMData.js

A NES emulator

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _registers = require("../../registers");
var _helpers = require("../../helpers");
/**
 * OAM Data Port (<> read/write)
 *
 * Write OAM data here. Writes will increment `OAMAddr` after the write.
 */
class OAMData extends _registers.InMemoryRegister {
  /** Reads a value from PPU's internal OAM. */
  readAt() {
    const {
      ppu
    } = this.context;
    const oamAddress = ppu.registers.oamAddr.value;
    return ppu.oamRam[oamAddress];
  }

  /** Writes a `byte` to PPU's internal OAM and increments `OAMAddr`. */
  writeAt(__, byte) {
    const {
      ppu
    } = this.context;
    const oamAddress = ppu.registers.oamAddr.value;
    ppu.oamRam[oamAddress] = byte;
    this._incrementAddress();
  }
  _incrementAddress() {
    const {
      oamAddr
    } = this.context.ppu.registers;
    oamAddr.setValue(_helpers.Byte.force8Bit(oamAddr.value + 1));
  }
}
exports.default = OAMData;