1 /* 2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1 3 Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file) 4 5 Stockfish is free software: you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation, either version 3 of the License, or 8 (at your option) any later version. 9 10 Stockfish is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <http://www.gnu.org/licenses/>. 17 */ 18 19 #ifndef SEARCH_H_INCLUDED 20 #define SEARCH_H_INCLUDED 21 22 #include <vector> 23 24 #include "misc.h" 25 #include "movepick.h" 26 #include "types.h" 27 28 namespace Stockfish { 29 30 class Position; 31 32 namespace Search { 33 34 /// Threshold used for countermoves based pruning 35 constexpr int CounterMovePruneThreshold = 0; 36 37 38 /// Stack struct keeps track of the information we need to remember from nodes 39 /// shallower and deeper in the tree during the search. Each search thread has 40 /// its own array of Stack objects, indexed by the current ply. 41 42 struct Stack { 43 Move* pv; 44 PieceToHistory* continuationHistory; 45 int ply; 46 Move currentMove; 47 Move excludedMove; 48 Move killers[2]; 49 Value staticEval; 50 int statScore; 51 int moveCount; 52 bool inCheck; 53 bool ttPv; 54 bool ttHit; 55 int doubleExtensions; 56 }; 57 58 59 /// RootMove struct is used for moves at the root of the tree. For each root move 60 /// we store a score and a PV (really a refutation in the case of moves which 61 /// fail low). Score is normally set at -VALUE_INFINITE for all non-pv moves. 62 63 struct RootMove { 64 RootMoveRootMove65 explicit RootMove(Move m) : pv(1, m) {} 66 bool extract_ponder_from_tt(Position& pos); 67 bool operator==(const Move& m) const { return pv[0] == m; } 68 bool operator<(const RootMove& m) const { // Sort in descending order 69 return m.score != score ? m.score < score 70 : m.previousScore < previousScore; 71 } 72 73 Value score = -VALUE_INFINITE; 74 Value previousScore = -VALUE_INFINITE; 75 int selDepth = 0; 76 int tbRank = 0; 77 Value tbScore; 78 std::vector<Move> pv; 79 }; 80 81 typedef std::vector<RootMove> RootMoves; 82 83 84 /// LimitsType struct stores information sent by GUI about available time to 85 /// search the current move, maximum depth/time, or if we are in analysis mode. 86 87 struct LimitsType { 88 LimitsTypeLimitsType89 LimitsType() { // Init explicitly due to broken value-initialization of non POD in MSVC 90 time[WHITE] = time[BLACK] = inc[WHITE] = inc[BLACK] = npmsec = movetime = TimePoint(0); 91 movestogo = depth = mate = perft = infinite = 0; 92 nodes = 0; 93 } 94 use_time_managementLimitsType95 bool use_time_management() const { 96 return time[WHITE] || time[BLACK]; 97 } 98 99 std::vector<Move> searchmoves; 100 TimePoint time[COLOR_NB], inc[COLOR_NB], npmsec, movetime, startTime; 101 int movestogo, depth, mate, perft, infinite; 102 int64_t nodes; 103 }; 104 105 extern LimitsType Limits; 106 107 void init(); 108 void clear(); 109 110 } // namespace Search 111 112 } // namespace Stockfish 113 114 #endif // #ifndef SEARCH_H_INCLUDED 115