voroskoi/pistike - Change A23ETUI3HMBQKCAROPWHAJ36CRQ3QFR27ZVRNJWDKAIPOBXYUAOAC

Implement incremental Zobrist hash updates

Created by voroskoi on January 29, 2023

A23ETUI3HMBQKCAROPWHAJ36CRQ3QFR27ZVRNJWDKAIPOBXYUAOAC

Dependencies

In channels

main

Change contents

Replacement in src/zobrist.zig at line 55 [2.36]

B:BD[2.1379] → [2.1379:1520]

    if (@bitCast(Board.CastlingType, gs.castling) != 0) {
        gs.hash ^= castle_hashes[@bitCast(Board.CastlingType, gs.castling)];
    }

[2.1379]

[2.1520]

    gs.hash ^= castle_hashes[@bitCast(Board.CastlingType, gs.castling)];

Insertion in src/perft.zig at line 4 [3.34]
[3.100]
[3.100]
```
const zobrist = @import("zobrist.zig");
```

Insertion in src/perft.zig at line 30 [3.34]

[3.630]

[4.148]

            // only for testing incremental Zobrist hash updates!
            // {
            //     const orig = self.gs.hash;
            //     zobrist.updateHash(&self.gs);
            //     if (orig != self.gs.hash) {
            //         std.log.err("{any}", .{mp.move});
            //         bk.show();
            //         self.gs.show();
            //         return error.HashMismatch;
            //     }
            // }

Replacement in src/Board.zig at line 181 [6.16071]

B:BD[5.1126] → [2.2926:2976]

∅:D[2.2976] → [5.1175:1269]

B:BD[5.1175] → [5.1175:1269]

        var ret = @bitCast(CastlingType, self.*);
        ret &= CASTLING_RIGHTS[@enumToInt(square)];
        self.* = @bitCast(Castling, ret);

[5.1126]

[5.1269]

        self.* = @bitCast(Castling, @bitCast(CastlingType, self.*) &
            CASTLING_RIGHTS[@enumToInt(square)]);

Insertion in src/Board.zig at line 239 [6.16071]
[6.21382]
[6.21406]
```
        new_gs.hash = self.hash;
```
Insertion in src/Board.zig at line 252 [6.16071]
[6.21755]
[6.21755]
```
        self.hash = bck.hash;
```

Insertion in src/Board.zig at line 751 [6.16071]

[7.5362]

[8.2568]


                // Zobrist: update piece hash
                self.hash ^= zobrist.piece_hashes[@enumToInt(move.piece)][@enumToInt(move.source)];
                self.hash ^= zobrist.piece_hashes[@enumToInt(move.piece)][@enumToInt(move.target)];

Insertion in src/Board.zig at line 787 [6.16071]

[7.5535]

[4.1793]


                                // Zobrist: update capture hash
                                self.hash ^= zobrist.piece_hashes[@enumToInt(piece)][@enumToInt(move.target)];

Insertion in src/Board.zig at line 803 [6.16071]

[7.5698]

[4.2267]


                        // Zobrist
                        self.hash ^= zobrist.piece_hashes[@enumToInt(move.piece)][@enumToInt(move.target)];
                        self.hash ^= zobrist.piece_hashes[@enumToInt(move.prom)][@enumToInt(move.target)];

Replacement in src/Board.zig at line 809 [6.16071]

B:BD[8.3701] → [4.2290:2332]

                    // handling enpassant

[8.3701]

[4.2332]

                    // handling enpassant captures

Replacement in src/Board.zig at line 812 [6.16071]

B:BD[4.2419] → [7.5699:5776]

∅:D[7.5776] → [4.2490:2577]

B:BD[4.2490] → [4.2490:2577]

B:BD[4.2577] → [7.5777:5854]

∅:D[7.5854] → [4.2648:2735]

B:BD[4.2648] → [4.2648:2735]

                            .white => self.bitboards[@enumToInt(Chess.PE.p)]
                                .pop(@intToEnum(Square, @enumToInt(move.target) + 8)),
                            .black => self.bitboards[@enumToInt(Chess.PE.P)]
                                .pop(@intToEnum(Square, @enumToInt(move.target) - 8)),

[4.2419]

[4.2735]

                            .white => {
                                self.bitboards[@enumToInt(Chess.PE.p)]
                                    .pop(@intToEnum(Square, @enumToInt(move.target) + 8));
                                // Zobrist
                                self.hash ^=
                                    zobrist.piece_hashes[@enumToInt(Chess.PE.p)][@enumToInt(move.target) + 8];
                            },
                            .black => {
                                self.bitboards[@enumToInt(Chess.PE.P)]
                                    .pop(@intToEnum(Square, @enumToInt(move.target) - 8));
                                // Zobrist
                                self.hash ^=
                                    zobrist.piece_hashes[@enumToInt(Chess.PE.P)][@enumToInt(move.target) - 8];
                            },

Insertion in src/Board.zig at line 828 [6.16071]

[3.6109]

[4.2762]

                    // Zobrist: remove enpassant hash
                    if (self.enpassant != null)
                        self.hash ^= zobrist.enpassant_hashes[@enumToInt(self.enpassant.?)];

Insertion in src/Board.zig at line 842 [6.16071]

[4.3247]

                        // Zobrist: add enpassant hash
                        self.hash ^= zobrist.enpassant_hashes[@enumToInt(enpassant)];

Insertion in src/Board.zig at line 856 [6.16071]

[3.6385]

[5.1687]


                                // Zobrist
                                self.hash ^= zobrist.piece_hashes[@enumToInt(Chess.PE.R)][@enumToInt(Square.h1)];
                                self.hash ^= zobrist.piece_hashes[@enumToInt(Chess.PE.R)][@enumToInt(Square.f1)];

Insertion in src/Board.zig at line 866 [6.16071]

[3.6586]

[5.1917]


                                // Zobrist
                                self.hash ^= zobrist.piece_hashes[@enumToInt(Chess.PE.R)][@enumToInt(Square.a1)];
                                self.hash ^= zobrist.piece_hashes[@enumToInt(Chess.PE.R)][@enumToInt(Square.d1)];

Insertion in src/Board.zig at line 876 [6.16071]

[3.6787]

[5.2147]


                                // Zobrist
                                self.hash ^= zobrist.piece_hashes[@enumToInt(Chess.PE.r)][@enumToInt(Square.h8)];
                                self.hash ^= zobrist.piece_hashes[@enumToInt(Chess.PE.r)][@enumToInt(Square.f8)];

Insertion in src/Board.zig at line 886 [6.16071]

[3.6988]

[5.2377]


                                // Zobrist
                                self.hash ^= zobrist.piece_hashes[@enumToInt(Chess.PE.r)][@enumToInt(Square.a8)];
                                self.hash ^= zobrist.piece_hashes[@enumToInt(Chess.PE.r)][@enumToInt(Square.d8)];

Insertion in src/Board.zig at line 894 [6.16071]

[5.2505]


                    // Zobrist - castling rights - remove all
                    self.hash ^= zobrist.castle_hashes[@bitCast(CastlingType, self.castling)];

Replacement in src/Board.zig at line 900 [6.16071]

B:BD[5.2607] → [5.2607:2662]

                    self.castling.update(move.target);

[5.2607]

[4.3270]

                    self.castling.update(move.target); // have to handle target too!
                    // Zobrist - castling rights - reset all
                    self.hash ^= zobrist.castle_hashes[@bitCast(CastlingType, self.castling)];

Insertion in src/Board.zig at line 926 [6.16071]

[4.4127]


                // update Zobrist hash
                self.hash ^= zobrist.side_hash;

Replacement in README.md at line 106 [10.34]

B:BD[9.701] → [9.701:871]

      - TODO: see comment below the [video](https://www.youtube.com/watch?v=n6xAzopULxU&list=PLmN0neTso3Jxh8ZIylk74JpwfiWNI76Cs&index=63), this is not a perfect solution

[9.701]

[11.1872]

    - Aspiration window

Insertion in README.md at line 126 [10.34]

[12.639]

- NULL move pruning: see comment below the [video](https://www.youtube.com/watch?v=n6xAzopULxU&list=PLmN0neTso3Jxh8ZIylk74JpwfiWNI76Cs&index=63), this is not a perfect solution

Insertion in README.md at line 130 [10.34]

[12.687]

- [Gigantua - fast movegen](https://www.codeproject.com/Articles/5313417/Worlds-fastest-Bitboard-Chess-Movegenerator)