stockfish_chess_engine 0.4.1

Use Stockfish chess engine directly in your Flutter project.

stockfish_chess_engine

Use Stockfish chess engine in your Flutter project.

This project is based on sources for Stockfish 15.

Note : I apologize for not releasing for IOS nor Mac, because I can't test on those machines. I'm open to pull request if someone can help me.

Usage

final stockfish = new Stockfish()

// Create a subscribtion on stdout : subscription that you'll have to cancel before disposing Stockfish.
final stockfishSubscription = stockfish.stdout.listen((message) {
    print(message);
});

// Get Stockfish ready
stockfish.stdin = 'isready'

// Send you commands to Stockfish stdin
stockfish.stdin = 'position startpos' // set up start position
stockfish.stdin = 'position fen rnbqkbnr/pp1ppppp/8/2p5/4P3/5N2/PPPP1PPP/RNBQKB1R b KQkq - 1 2' // set up custom position
stockfish.stdin = 'go movetime 1500' // search move for at most 1500ms

// Don't remember to dispose Stockfish when you're done.
stockfishSubscription.cancel();
stockfish.dispose();

You can see an example usage in example folder.

Important notes

• You must check the position validity before sending it to stdin, otherwise program will crash on illegal position ! For that, you can use the chess package.

• As the library creates two isolates, you must dispose Stockfish before perfoming an hot reload / hot restart, and then creating a new Stockfish instance.

For stockfish chess engine developpers

1. Run flutter pub get.
2. Uncomment line #define _ffigen on top of src/stockfish.h (for the ffi generation to pass).
3. Run command flutter pub run ffigen --config ffigen.yaml. More on https://pub.dev/packages/ffigen for the prerequesites per OS.
4. Comment line #define _ffigen in src/stockfish.h (otherwise Stockfish engine compilation will pass but be incorrect).
5. In the file lib/stockfish_bindings_generated.dart, add the following import line : import 'package:ffi/ffi.dart';
6. In the same file, replace Pointer<ffi.Char> by Pointer

Changing the downloaded NNUE file

1. Go to Stockfish NNUE files page and select a reference from the list.
2. Modify CMakeLists.txt, by replacing lines starting by set (NNUE_NAME ) by setting your reference name, without any quote.
3. Modify the reference name in evaluate.h in the line containing #define EvalFileDefaultName , by setting your nnue file name, with the quotes of course.
4. Don't forget to clean project before building again (flutter clean then flutter pub get).

Credits

• Using source code from Stockfish.
• Using source code from Flutter Stockfish.