broken-neees/ppu/PPU.js

A really broken NEEES emulator that introduces glitches and random bugs on purpose!

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;
var _PPUMemory = _interopRequireDefault(require("./PPUMemory"));
var _VideoRegisters = _interopRequireDefault(require("./VideoRegisters"));
var _BackgroundRenderer = _interopRequireDefault(require("./BackgroundRenderer"));
var _SpriteRenderer = _interopRequireDefault(require("./SpriteRenderer"));
var _LoopyRegister = _interopRequireDefault(require("../lib/ppu/LoopyRegister"));
var _masterPalette = _interopRequireDefault(require("../lib/ppu/masterPalette"));
var _interrupts = _interopRequireDefault(require("../lib/cpu/interrupts"));
function _interopRequireDefault(e) { return e && e.__esModule ? e : { default: e }; }
const MEM_PALETTE = 0x3f00;
const PALETTE_SIZE_BYTES = 4;
class PPU {
  constructor(cpu) {
    this.cpu = cpu;
    this.cycle = 0;
    this.scanline = -1;
    this.frame = 0;
    this.memory = new _PPUMemory.default();
    this.registers = new _VideoRegisters.default(this);
    this.loopy = new _LoopyRegister.default();
    this.frameBuffer = new Uint32Array(256 * 240);
    this.colorIndexes = new Uint8Array(256 * 240);
    this.backgroundRenderer = new _BackgroundRenderer.default(this);
    this.spriteRenderer = new _SpriteRenderer.default(this);
  }
  onLoad(mapper) {
    this.mapper = mapper;
  }
  step(onFrame, onInterrupt) {
    if (this.scanline === -1) this._onPreLine();else if (this.scanline >= 0 && this.scanline < 240) this._onVisibleLine();else if (this.scanline === 241) this._onVBlankLine(onInterrupt);
    this._incrementCounters(onFrame);
  }
  plotBG(x, y, color, colorIndex) {
    this.colorIndexes[y * 256 + x] = colorIndex;
    this.plot(x, y, color);
    if (this.registers.ppuMask.showBackground) this.loopy.onPlot(x);
  }
  plot(x, y, color) {
    this.frameBuffer[y * 256 + x] = this.registers.ppuMask.transform(color);
  }
  isBackgroundPixelOpaque(x, y) {
    return this.colorIndexes[y * 256 + x] > 0;
  }
  getPaletteColors(paletteId) {
    return [this.getColor(paletteId, 0), this.getColor(paletteId, 1), this.getColor(paletteId, 2), this.getColor(paletteId, 3)];
  }
  getColor(paletteId, paletteIndex) {
    const startAddress = MEM_PALETTE + paletteId * PALETTE_SIZE_BYTES;
    const colorIndex = this.memory.read(startAddress + paletteIndex);
    return _masterPalette.default[colorIndex];
  }
  _onPreLine() {
    if (!this.registers.ppuMask.isRenderingEnabled()) return;
    if (this.cycle === 1) {
      this.registers.ppuStatus.spriteOverflow = 0;
      this.registers.ppuStatus.sprite0Hit = 0;
      this.registers.ppuStatus.isInVBlankInterval = 0;
    }
    this.loopy.onPreLine(this.cycle);
    if (this.cycle === 260) this.mapper.tick();
  }
  _onVisibleLine() {
    if (this.cycle === 0) {
      this.backgroundRenderer.renderScanline();
      this.spriteRenderer.renderScanline();
    }
    if (!this.registers.ppuMask.isRenderingEnabled()) return;
    this.loopy.onVisibleLine(this.cycle);
    if (this.cycle === 260) this.mapper.tick();
  }
  _onVBlankLine(onInterrupt) {
    if (this.cycle === 1) {
      this.registers.ppuStatus.isInVBlankInterval = 1;
      if (this.registers.ppuCtrl.generateNMIOnVBlank) {
        onInterrupt(_interrupts.default.NMI);
      }
    }
  }
  _incrementCounters(onFrame) {
    this.cycle++;
    if (this.cycle >= 341) {
      this.cycle = 0;
      this.scanline++;
      if (this.scanline >= 261) {
        this.scanline = -1;
        this.frame++;
        onFrame(this.frameBuffer);
      }
    }
  }
}
exports.default = PPU;