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  1. /*
  2.   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
  3.   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
  4.   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
  5.   Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
  6.  
  7.   Stockfish is free software: you can redistribute it and/or modify
  8.   it under the terms of the GNU General Public License as published by
  9.   the Free Software Foundation, either version 3 of the License, or
  10.   (at your option) any later version.
  11.  
  12.   Stockfish is distributed in the hope that it will be useful,
  13.   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.   GNU General Public License for more details.
  16.  
  17.   You should have received a copy of the GNU General Public License
  18.   along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19. */
  20.  
  21. #ifndef SEARCH_H_INCLUDED
  22. #define SEARCH_H_INCLUDED
  23.  
  24. #include <atomic>
  25. #include <memory>  // For std::unique_ptr
  26. #include <stack>
  27. #include <vector>
  28.  
  29. #include "misc.h"
  30. #include "position.h"
  31. #include "types.h"
  32.  
  33. namespace Search {
  34.  
  35. /// Stack struct keeps track of the information we need to remember from nodes
  36. /// shallower and deeper in the tree during the search. Each search thread has
  37. /// its own array of Stack objects, indexed by the current ply.
  38.  
  39. struct Stack {
  40.   Move* pv;
  41.   int ply;
  42.   Move currentMove;
  43.   Move excludedMove;
  44.   Move killers[2];
  45.   Value staticEval;
  46.   bool skipEarlyPruning;
  47.   int moveCount;
  48. };
  49.  
  50. /// RootMove struct is used for moves at the root of the tree. For each root move
  51. /// we store a score and a PV (really a refutation in the case of moves which
  52. /// fail low). Score is normally set at -VALUE_INFINITE for all non-pv moves.
  53.  
  54. struct RootMove {
  55.  
  56.   explicit RootMove(Move m) : pv(1, m) {}
  57.  
  58.   bool operator<(const RootMove& m) const { return m.score < score; } // Descending sort
  59.   bool operator==(const Move& m) const { return pv[0] == m; }
  60.   void insert_pv_in_tt(Position& pos);
  61.   bool extract_ponder_from_tt(Position& pos);
  62.  
  63.   Value score = -VALUE_INFINITE;
  64.   Value previousScore = -VALUE_INFINITE;
  65.   std::vector<Move> pv;
  66. };
  67.  
  68. typedef std::vector<RootMove> RootMoveVector;
  69.  
  70. /// LimitsType struct stores information sent by GUI about available time to
  71. /// search the current move, maximum depth/time, if we are in analysis mode or
  72. /// if we have to ponder while it's our opponent's turn to move.
  73.  
  74. struct LimitsType {
  75.  
  76.   LimitsType() { // Init explicitly due to broken value-initialization of non POD in MSVC
  77.     nodes = time[WHITE] = time[BLACK] = inc[WHITE] = inc[BLACK] = npmsec = movestogo =
  78.     depth = movetime = mate = infinite = ponder = 0;
  79.   }
  80.  
  81.   bool use_time_management() const {
  82.     return !(mate | movetime | depth | nodes | infinite);
  83.   }
  84.  
  85.   std::vector<Move> searchmoves;
  86.   int time[COLOR_NB], inc[COLOR_NB], npmsec, movestogo, depth, movetime, mate, infinite, ponder;
  87.   int64_t nodes;
  88.   TimePoint startTime;
  89. };
  90.  
  91. /// The SignalsType struct stores atomic flags updated during the search
  92. /// typically in an async fashion e.g. to stop the search by the GUI.
  93.  
  94. struct SignalsType {
  95.   std::atomic_bool stop, stopOnPonderhit;
  96. };
  97.  
  98. typedef std::unique_ptr<std::stack<StateInfo>> StateStackPtr;
  99.  
  100. extern SignalsType Signals;
  101. extern LimitsType Limits;
  102. extern StateStackPtr SetupStates;
  103.  
  104. void init();
  105. void clear();
  106. template<bool Root = true> uint64_t perft(Position& pos, Depth depth);
  107.  
  108. } // namespace Search
  109.  
  110. #endif // #ifndef SEARCH_H_INCLUDED
  111.