multistockfish

Multiple flavors of Stockfish Engine.

This plugin provides the following Stockfish engines:

• Stockfish 16, with embedded NNUE (38MB)
• Stockfish 17.1, without embedded NNUE
• Fairy-Stockfish, for chess variants

Usage

Init engine

[!WARNING] Only one instance can be created at a time. The Stockfish() constructor will throw a StateError if called while another instance is running.

[!NOTE] When using the StockfishFlavor.latestNoNNUE flavor, you need to download the .nnue files before starting an evaluation, since it is not embedded in the binary.

import 'package:multistockfish/multistockfish.dart';

// create a new instance
final stockfish = Stockfish();

// state is a ValueListenable<StockfishState>
print(stockfish.state.value); # StockfishState.starting

// the engine takes a few moment to start
await Future.delayed(...)
print(stockfish.state.value); # StockfishState.ready

UCI command

Wait until the state is ready before sending commands.

stockfish.stdin = 'isready';
stockfish.stdin = 'go movetime 3000';
stockfish.stdin = 'go infinite';
stockfish.stdin = 'stop';

Engine output is directed to a Stream<String>, add a listener to process results.

stockfish.stdout.listen((line) {
  // do something useful
  print(line);
});

Dispose / Hot reload

There are two active isolates when Stockfish engine is running. That interferes with Flutter's hot reload feature so you need to dispose it before attempting to reload.

// sends the UCI quit command
stockfish.stdin = 'quit';

// or even easier...
stockfish.dispose();