nes-emu/ppu/registers/PPUCtrl.js

A NES emulator

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _registers = require("../../registers");
/**
 * PPU Control Register (> write)
 *
 * Contains various flags controlling PPU operation.
 * Connected to `LoopyRegister`.
 */
class PPUCtrl extends _registers.WriteOnlyInMemoryRegister {
  constructor() {
    super();
    this.addReadOnlyField("vramAddressIncrement32", 2).addReadOnlyField("patternTableAddressIdFor8x8Sprites", 3).addReadOnlyField("patternTableAddressIdForBackground", 4).addReadOnlyField("spriteSizeId", 5).addReadOnlyField("generateNmiAtStartOfVBlank", 7);
  }

  /** Sets the actual value and updates scrolling metadata. */
  writeAt(__, byte) {
    this.setValue(byte);
    this.context.ppu.loopy.onPPUCtrlWrite(byte);
  }

  /** Returns the `PPUAddr` increment per CPU read/write of `PPUData`. */
  get vramAddressIncrement() {
    return this.vramAddressIncrement32 ? 32 : 1;
  }

  /** Returns true if sprites are 8x16. Otherwise, they're 8x8. */
  get isIn8x16Mode() {
    return this.spriteSizeId === 1;
  }
}
exports.default = PPUCtrl;