Line data    Source code

       1              : #pragma once
       2              : 
       3              : #include "definition.hpp"
       4              : 
       5              : struct Position;
       6              : 
       7              : /*!
       8              :  * A simple Zobrist hash implementation
       9              :  */
      10              : namespace Zobrist {
      11              : extern array2d<Hash,NbSquare,14> ZT; // should be 13 but last ray is for castling[0 7 56 63][13] and ep [k][13] and Color [3 4][13]
      12              : extern array1d<Hash,16> ZTCastling; // castling
      13              : 
      14              : void initHash();
      15              : 
      16              : // Compute hash for a move using from/to squares
      17              : // Uses unused ZT slot [5][NbPiece] to add variation
      18        44704 : [[nodiscard]] constexpr Hash hashMove(MiniMove m) {
      19        44704 :    const Square from = Move2From(m);
      20        44704 :    const Square to = Move2To(m);
      21        44704 :    return ZT[from][NbPiece] ^ ZT[to][NbPiece] ^ ZT[5][NbPiece];
      22              : }
      23              : } // namespace Zobrist
      24              : 
      25              : // Position hash is computed only once and then updated on the fly
      26              : // But this encapsulating function is usefull for debugging
      27              : [[nodiscard]] Hash computeHash(const Position &p);
      28              : 
      29              : // Same holds from K+P hash (used for pawn hash table)
      30              : [[nodiscard]] Hash computePHash(const Position &p);