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) 2015-2019 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 <vector>
25
26#include "misc.h"
27#include "movepick.h"
28#include "types.h"
29
30class Position;
31
32namespace Search {
33
34/// Threshold used for countermoves based pruning
35constexpr 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
42struct 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};
53
54
55/// RootMove struct is used for moves at the root of the tree. For each root move
56/// we store a score and a PV (really a refutation in the case of moves which
57/// fail low). Score is normally set at -VALUE_INFINITE for all non-pv moves.
58
59struct RootMove {
60
61 explicit RootMove(Move m) : pv(1, m) {}
62 bool extract_ponder_from_tt(Position& pos);
63 bool operator==(const Move& m) const { return pv[0] == m; }
64 bool operator<(const RootMove& m) const { // Sort in descending order
65 return m.score != score ? m.score < score
66 : m.previousScore < previousScore;
67 }
68
69 Value score = -VALUE_INFINITE;
70 Value previousScore = -VALUE_INFINITE;
71 int selDepth = 0;
72 int tbRank = 0;
73 Value tbScore;
74 std::vector<Move> pv;
75};
76
77typedef std::vector<RootMove> RootMoves;
78
79
80/// LimitsType struct stores information sent by GUI about available time to
81/// search the current move, maximum depth/time, or if we are in analysis mode.
82
83struct LimitsType {
84
85 LimitsType() { // Init explicitly due to broken value-initialization of non POD in MSVC
86 time[WHITE] = time[BLACK] = inc[WHITE] = inc[BLACK] = npmsec = movetime = TimePoint(0);
87 movestogo = depth = mate = perft = infinite = 0;
88 nodes = 0;
89 }
90
91 bool use_time_management() const {
92 return !(mate | movetime | depth | nodes | perft | infinite);
93 }
94
95 std::vector<Move> searchmoves;
96 TimePoint time[COLOR_NB], inc[COLOR_NB], npmsec, movetime, startTime;
97 int movestogo, depth, mate, perft, infinite;
98 int64_t nodes;
99};
100
101extern LimitsType Limits;
102
103void init();
104void clear();
105
106} // namespace Search
107
108#endif // #ifndef SEARCH_H_INCLUDED
109