cfxnes (core)

Core of the cfxnes emulator.

Its components can be used independently in browser or in Node.js environment.

For better performance, these components can be compiled with closure compiler in ADVANCED optimization mode.

Initialization

import {NES} from 'cfxnes-core';

const nes = new NES;

NES constructor allows to pass custom implementation of any internal unit (CPU, PPU, APU, DMA, CPUMemory, PPUMemory). This is mainly used for their mocking/customization in tests.

const nes = new NES({cpu: customCPU});

ROM Images

ROM image can be loaded from Uint8Array or from a file system path when running in Node.js. Supported formats are iNES and NES 2.0.

import {createCartridge, readCartridge} from 'cfxnes-core';

// From buffer
const cartridge1 = createCartridge(uint8Array);
nes.setCartridge(cartridge1);

// From file system
const cartridge2 = readCartridge('./data/rom.nes');
nes.setCartridge(cartridge2);

Rendering Loop

Video output is rendered into provided Uint32Array(256 * 240) buffer. Color of each pixel is encoded as 32-bit unsigned integer in RGBA format. Their values are generated using specified Uint32Array(64) palette.

import {createPalette, VIDEO_WIDTH, VIDEO_HEIGHT} from 'cfxnes-core';

const palette = createPalette('fceux'); // Predefined palette
nes.setPalette(palette);

const videoBuffer = new Uint32Array(VIDEO_WIDTH * VIDEO_HEIGHT);
while (running) {
    nes.renderFrame(videoBuffer);
    // Display video buffer
    // Add delay to run loop at speed of 60 FPS (NTSC) or 50 FPS (PAL)
}

Audio Output

During the rendering loop, audio samples are generated at a specified rate. These samples are then passed to a provided callback function.

nes.setAudioSampleRate(44100); // 44.1 KHz sampling rate
nes.setAudioCallback(audioSample => { /* Handle audio sample. */ });

// Rendering loop

Input Devices

import {Button, Joypad, Zapper} from 'cfxnes-core';

// Standard NES controller
const joypad = new Joypad;
nes.setInputDevice(1, joypad); // Port #1
joypad.setButtonPressed(Button.START, true);

// Zapper
const zapper = new Zapper;
nes.setInputDevice(2, zapper); // Port #2
zapper.setBeamPosition(128, 120);
zapper.setTriggerPressed(true);

Development

npm run <script>	Description
lint	Run linter.
test	Run all tests.
test:base	Run tests for source modules.
test:roms	Run tests that are using various validation ROMs.
clean	Clean all generated files.