#chess-engine #chess #syzygy #tablebase

pyrrhic-rs

A pure-Rust library to probe Syzygy Tablebases within a chess engine

2 unstable releases

0.2.0 Mar 28, 2024
0.1.0 Mar 26, 2024

#439 in Game dev

34 downloads per month

MIT license

135KB
3.5K SLoC

Pyrrhic-rs

pyrrhic-rs is a library for use in chess engines to probe the Syzygy endgame tablesbases during a search.

Usage

Pyrrhic's original API is unsafe, with potential for memory corruption if used improperly. Therefore pyrrhic-rs wraps this unsafe API in the TableBases struct, which guards against memory- and thread-unsafe usage of the Pyrrhic API.

As pyrrhic-rs is designed to be used within an existing engine, the user must implement the EngineAdapter trait on a type for the probing code to be able to use the engine's own move generation code. Afterwards, Tablebases::new() can be called using this type as a parameter.

Example using cozy_chess:

use cozy_chess::*;

struct CozyChessAdapter;

impl EngineAdapter for CozyChessAdapter {
    fn pawn_attacks(color: pyrrhic_rs::Color, sq: u64) -> u64 {
        let attacks = get_pawn_attacks(
            Square::index(sq as usize),
            if color == pyrrhic_rs::Color::Black {
                Color::Black
            } else {
                Color::White
            },
        );
        attacks.0
    }
    fn knight_attacks(sq: u64) -> u64 {
        get_knight_moves(Square::index(sq as usize)).0
    }
    fn bishop_attacks(sq: u64, occ: u64) -> u64 {
        get_bishop_moves(Square::index(sq as usize), BitBoard(occ)).0
    }
    fn rook_attacks(sq: u64, occ: u64) -> u64 {
        get_rook_moves(Square::index(sq as usize), BitBoard(occ)).0
    }
    fn king_attacks(sq: u64) -> u64 {
        get_king_moves(Square::index(sq as usize)).0
    }
    fn queen_attacks(sq: u64, occ: u64) -> u64 {
        (get_bishop_moves(Square::index(sq as usize), BitBoard(occ))
            | get_rook_moves(Square::index(sq as usize), BitBoard(occ)))
        .0
    }
}

fn main() {
    let tb = pyrrhic_rs::TableBases::<CozyChessAdapter>::new("./syzygy/tb345:./syzygy/tb6:./syzygy/tb7").unwrap();
}

pyrrhic-rs was initially transliterated from the original Pyrrhic library in C, and is therefore subject to the following copyrights:

  • Fathom © 2015 basil, all rights reserved
  • Modifications Copyright © 2016-2019 by Jon Dart
  • Modifications Copyright © 2020-2020 by Andrew Grant

Acknowledgments

  • Ronald "Syzygy" de Man, creator of the Syzygy tablebases
  • C2Rust, used to initally translate the C code into Rust code

Dependencies

~165KB