2011-11-12 20:44:06 +01:00
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/*
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Stockfish, a UCI chess playing engine derived from Glaurung 2.1
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Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
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2014-05-31 14:23:03 +02:00
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Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
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2011-11-12 20:44:06 +01:00
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Stockfish is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Stockfish is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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2012-01-01 01:52:19 +01:00
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#include <algorithm>
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2011-11-12 20:44:06 +01:00
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#include <cassert>
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2013-11-30 20:12:34 +01:00
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#include <cfloat>
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2011-11-12 20:44:06 +01:00
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#include <cmath>
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#include <cstring>
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#include <iostream>
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#include <sstream>
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#include "book.h"
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#include "evaluate.h"
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#include "movegen.h"
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#include "movepick.h"
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2012-09-16 17:16:15 +02:00
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#include "notation.h"
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2011-11-12 20:44:06 +01:00
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#include "search.h"
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#include "timeman.h"
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#include "thread.h"
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#include "tt.h"
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#include "ucioption.h"
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2012-01-01 01:52:19 +01:00
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namespace Search {
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volatile SignalsType Signals;
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LimitsType Limits;
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2012-01-15 02:13:33 +01:00
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std::vector<RootMove> RootMoves;
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2013-05-03 19:03:42 +02:00
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Position RootPos;
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Color RootColor;
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2012-09-16 17:16:15 +02:00
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Time::point SearchTime;
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StateStackPtr SetupStates;
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2012-01-01 01:52:19 +01:00
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}
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using std::string;
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2012-06-04 18:25:51 +02:00
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using Eval::evaluate;
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2012-01-01 01:52:19 +01:00
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using namespace Search;
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2011-11-12 20:44:06 +01:00
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namespace {
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// Set to true to force running with one thread. Used for debugging
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const bool FakeSplit = false;
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// Different node types, used as template parameter
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2014-05-31 14:23:03 +02:00
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enum NodeType { Root, PV, NonPV };
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2011-11-12 20:44:06 +01:00
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// Dynamic razoring margin based on depth
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2014-05-31 14:23:03 +02:00
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inline Value razor_margin(Depth d) { return Value(512 + 16 * d); }
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2011-11-12 20:44:06 +01:00
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// Futility lookup tables (initialized at startup) and their access functions
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2013-08-20 20:02:33 +02:00
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int FutilityMoveCounts[2][32]; // [improving][depth]
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2011-11-12 20:44:06 +01:00
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2013-11-30 20:12:34 +01:00
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inline Value futility_margin(Depth d) {
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2014-05-31 14:23:03 +02:00
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return Value(100 * d);
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2011-11-12 20:44:06 +01:00
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}
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// Reduction lookup tables (initialized at startup) and their access function
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2013-08-20 20:02:33 +02:00
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int8_t Reductions[2][2][64][64]; // [pv][improving][depth][moveNumber]
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2011-11-12 20:44:06 +01:00
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2013-08-20 20:02:33 +02:00
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template <bool PvNode> inline Depth reduction(bool i, Depth d, int mn) {
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2011-11-12 20:44:06 +01:00
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2013-08-20 20:02:33 +02:00
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return (Depth) Reductions[PvNode][i][std::min(int(d) / ONE_PLY, 63)][std::min(mn, 63)];
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2011-11-12 20:44:06 +01:00
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}
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2014-05-31 14:23:03 +02:00
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size_t MultiPV, PVIdx;
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2011-11-12 20:44:06 +01:00
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TimeManager TimeMgr;
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2013-11-30 20:12:34 +01:00
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double BestMoveChanges;
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2013-05-03 19:03:42 +02:00
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Value DrawValue[COLOR_NB];
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2013-08-20 20:02:33 +02:00
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HistoryStats History;
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GainsStats Gains;
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2014-05-31 14:23:03 +02:00
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MovesStats Countermoves, Followupmoves;
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2011-11-12 20:44:06 +01:00
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2014-05-31 14:23:03 +02:00
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template <NodeType NT, bool SpNode>
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2013-08-20 20:02:33 +02:00
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Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
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2011-11-12 20:44:06 +01:00
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2013-05-03 19:03:42 +02:00
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template <NodeType NT, bool InCheck>
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2012-01-01 01:52:19 +01:00
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Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth);
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2011-11-12 20:44:06 +01:00
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2012-01-01 01:52:19 +01:00
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void id_loop(Position& pos);
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2011-11-12 20:44:06 +01:00
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Value value_to_tt(Value v, int ply);
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Value value_from_tt(Value v, int ply);
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2014-05-31 14:23:03 +02:00
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void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt);
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2012-09-16 17:16:15 +02:00
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string uci_pv(const Position& pos, int depth, Value alpha, Value beta);
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2011-11-12 20:44:06 +01:00
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2013-05-03 19:03:42 +02:00
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struct Skill {
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Skill(int l) : level(l), best(MOVE_NONE) {}
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~Skill() {
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if (enabled()) // Swap best PV line with the sub-optimal one
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std::swap(RootMoves[0], *std::find(RootMoves.begin(),
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RootMoves.end(), best ? best : pick_move()));
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}
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2011-11-12 20:44:06 +01:00
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2013-05-03 19:03:42 +02:00
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bool enabled() const { return level < 20; }
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bool time_to_pick(int depth) const { return depth == 1 + level; }
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Move pick_move();
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2012-01-01 01:52:19 +01:00
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2013-05-03 19:03:42 +02:00
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int level;
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Move best;
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};
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2011-11-12 20:44:06 +01:00
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} // namespace
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2012-01-01 01:52:19 +01:00
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/// Search::init() is called during startup to initialize various lookup tables
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2011-11-12 20:44:06 +01:00
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2012-01-01 01:52:19 +01:00
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void Search::init() {
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2011-11-12 20:44:06 +01:00
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int d; // depth (ONE_PLY == 2)
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int hd; // half depth (ONE_PLY == 1)
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int mc; // moveCount
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// Init reductions array
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2013-11-30 20:12:34 +01:00
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for (hd = 1; hd < 64; ++hd) for (mc = 1; mc < 64; ++mc)
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2011-11-12 20:44:06 +01:00
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{
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2014-05-31 14:23:03 +02:00
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double pvRed = 0.00 + log(double(hd)) * log(double(mc)) / 3.00;
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2011-11-12 20:44:06 +01:00
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double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25;
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2014-05-31 14:23:03 +02:00
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Reductions[1][1][hd][mc] = int8_t( pvRed >= 1.0 ? pvRed * int(ONE_PLY) : 0);
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Reductions[0][1][hd][mc] = int8_t(nonPVRed >= 1.0 ? nonPVRed * int(ONE_PLY) : 0);
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2013-08-20 20:02:33 +02:00
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Reductions[1][0][hd][mc] = Reductions[1][1][hd][mc];
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Reductions[0][0][hd][mc] = Reductions[0][1][hd][mc];
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if (Reductions[0][0][hd][mc] > 2 * ONE_PLY)
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Reductions[0][0][hd][mc] += ONE_PLY;
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2011-11-12 20:44:06 +01:00
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2013-11-30 20:12:34 +01:00
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else if (Reductions[0][0][hd][mc] > 1 * ONE_PLY)
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Reductions[0][0][hd][mc] += ONE_PLY / 2;
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}
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2011-11-12 20:44:06 +01:00
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// Init futility move count array
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2013-11-30 20:12:34 +01:00
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for (d = 0; d < 32; ++d)
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2013-08-20 20:02:33 +02:00
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{
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2014-05-31 14:23:03 +02:00
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FutilityMoveCounts[0][d] = int(2.4 + 0.222 * pow(d + 0.00, 1.8));
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FutilityMoveCounts[1][d] = int(3.0 + 0.300 * pow(d + 0.98, 1.8));
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2013-08-20 20:02:33 +02:00
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}
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2011-11-12 20:44:06 +01:00
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}
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2012-01-01 01:52:19 +01:00
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/// Search::perft() is our utility to verify move generation. All the leaf nodes
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/// up to the given depth are generated and counted and the sum returned.
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2011-11-12 20:44:06 +01:00
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2014-05-31 14:23:03 +02:00
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static uint64_t perft(Position& pos, Depth depth) {
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2011-11-12 20:44:06 +01:00
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2012-09-16 17:16:15 +02:00
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StateInfo st;
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2014-05-31 14:23:03 +02:00
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uint64_t cnt = 0;
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2011-11-12 20:44:06 +01:00
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CheckInfo ci(pos);
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2013-08-20 20:02:33 +02:00
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const bool leaf = depth == 2 * ONE_PLY;
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2012-09-16 17:16:15 +02:00
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2013-08-20 20:02:33 +02:00
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for (MoveList<LEGAL> it(pos); *it; ++it)
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2011-11-12 20:44:06 +01:00
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{
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2013-11-30 20:12:34 +01:00
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pos.do_move(*it, st, ci, pos.gives_check(*it, ci));
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2013-08-20 20:02:33 +02:00
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cnt += leaf ? MoveList<LEGAL>(pos).size() : ::perft(pos, depth - ONE_PLY);
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pos.undo_move(*it);
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2011-11-12 20:44:06 +01:00
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}
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2012-01-01 01:52:19 +01:00
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return cnt;
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2011-11-12 20:44:06 +01:00
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}
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2014-05-31 14:23:03 +02:00
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uint64_t Search::perft(Position& pos, Depth depth) {
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2013-08-20 20:02:33 +02:00
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return depth > ONE_PLY ? ::perft(pos, depth) : MoveList<LEGAL>(pos).size();
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}
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2011-11-12 20:44:06 +01:00
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2012-01-01 01:52:19 +01:00
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/// Search::think() is the external interface to Stockfish's search, and is
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/// called by the main thread when the program receives the UCI 'go' command. It
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2013-05-03 19:03:42 +02:00
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/// searches from RootPos and at the end prints the "bestmove" to output.
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2011-11-12 20:44:06 +01:00
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2012-01-01 01:52:19 +01:00
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void Search::think() {
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2011-11-12 20:44:06 +01:00
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2012-09-23 10:13:11 +02:00
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static PolyglotBook book; // Defined static to initialize the PRNG only once
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2011-11-12 20:44:06 +01:00
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2013-05-03 19:03:42 +02:00
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RootColor = RootPos.side_to_move();
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TimeMgr.init(Limits, RootPos.game_ply(), RootColor);
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2012-01-01 01:52:19 +01:00
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2014-05-31 14:23:03 +02:00
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int cf = Options["Contempt Factor"] * PawnValueEg / 100; // From centipawns
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DrawValue[ RootColor] = VALUE_DRAW - Value(cf);
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DrawValue[~RootColor] = VALUE_DRAW + Value(cf);
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2012-01-15 02:13:33 +01:00
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if (RootMoves.empty())
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2011-11-12 20:44:06 +01:00
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{
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2013-05-03 19:03:42 +02:00
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RootMoves.push_back(MOVE_NONE);
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2012-09-16 17:16:15 +02:00
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sync_cout << "info depth 0 score "
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2013-05-03 19:03:42 +02:00
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<< score_to_uci(RootPos.checkers() ? -VALUE_MATE : VALUE_DRAW)
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<< sync_endl;
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2011-11-12 20:44:06 +01:00
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2012-01-15 02:13:33 +01:00
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goto finalize;
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}
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2013-05-03 19:03:42 +02:00
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if (Options["OwnBook"] && !Limits.infinite && !Limits.mate)
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2012-01-15 02:13:33 +01:00
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{
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2013-05-03 19:03:42 +02:00
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Move bookMove = book.probe(RootPos, Options["Book File"], Options["Best Book Move"]);
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2011-11-12 20:44:06 +01:00
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2012-09-16 17:16:15 +02:00
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if (bookMove && std::count(RootMoves.begin(), RootMoves.end(), bookMove))
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2012-06-04 18:25:51 +02:00
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{
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2012-09-16 17:16:15 +02:00
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std::swap(RootMoves[0], *std::find(RootMoves.begin(), RootMoves.end(), bookMove));
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2012-06-04 18:25:51 +02:00
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goto finalize;
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}
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2011-11-12 20:44:06 +01:00
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}
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2013-08-20 20:02:33 +02:00
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if (Options["Write Search Log"])
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2011-11-12 20:44:06 +01:00
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{
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2012-01-01 01:52:19 +01:00
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Log log(Options["Search Log Filename"]);
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2013-05-03 19:03:42 +02:00
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log << "\nSearching: " << RootPos.fen()
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2012-01-01 01:52:19 +01:00
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<< "\ninfinite: " << Limits.infinite
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<< " ponder: " << Limits.ponder
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2013-05-03 19:03:42 +02:00
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<< " time: " << Limits.time[RootColor]
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<< " increment: " << Limits.inc[RootColor]
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2012-06-04 18:25:51 +02:00
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<< " moves to go: " << Limits.movestogo
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2014-05-31 14:23:03 +02:00
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<< "\n" << std::endl;
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2011-11-12 20:44:06 +01:00
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}
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2014-05-31 14:23:03 +02:00
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// Reset the threads, still sleeping: will wake up at split time
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2013-11-30 20:12:34 +01:00
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for (size_t i = 0; i < Threads.size(); ++i)
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2013-05-03 19:03:42 +02:00
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Threads[i]->maxPly = 0;
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2013-11-30 20:12:34 +01:00
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Threads.timer->run = true;
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2013-05-03 19:03:42 +02:00
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Threads.timer->notify_one(); // Wake up the recurring timer
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2011-11-12 20:44:06 +01:00
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2013-05-03 19:03:42 +02:00
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id_loop(RootPos); // Let's start searching !
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2013-11-30 20:12:34 +01:00
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Threads.timer->run = false; // Stop the timer
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2011-11-12 20:44:06 +01:00
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2013-08-20 20:02:33 +02:00
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if (Options["Write Search Log"])
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2011-11-12 20:44:06 +01:00
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{
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2012-09-16 17:16:15 +02:00
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Time::point elapsed = Time::now() - SearchTime + 1;
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2011-11-12 20:44:06 +01:00
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2012-01-01 01:52:19 +01:00
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Log log(Options["Search Log Filename"]);
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2013-05-03 19:03:42 +02:00
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log << "Nodes: " << RootPos.nodes_searched()
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<< "\nNodes/second: " << RootPos.nodes_searched() * 1000 / elapsed
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<< "\nBest move: " << move_to_san(RootPos, RootMoves[0].pv[0]);
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2011-11-12 20:44:06 +01:00
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StateInfo st;
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2013-05-03 19:03:42 +02:00
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RootPos.do_move(RootMoves[0].pv[0], st);
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log << "\nPonder move: " << move_to_san(RootPos, RootMoves[0].pv[1]) << std::endl;
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RootPos.undo_move(RootMoves[0].pv[0]);
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2011-11-12 20:44:06 +01:00
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}
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2012-01-07 03:07:28 +01:00
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finalize:
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2011-11-12 20:44:06 +01:00
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2013-08-20 20:02:33 +02:00
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// When search is stopped this info is not printed
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sync_cout << "info nodes " << RootPos.nodes_searched()
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<< " time " << Time::now() - SearchTime + 1 << sync_endl;
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// When we reach the maximum depth, we can arrive here without a raise of
|
|
|
|
// Signals.stop. However, if we are pondering or in an infinite search,
|
|
|
|
// the UCI protocol states that we shouldn't print the best move before the
|
|
|
|
// GUI sends a "stop" or "ponderhit" command. We therefore simply wait here
|
|
|
|
// until the GUI sends one of those commands (which also raises Signals.stop).
|
2012-01-01 01:52:19 +01:00
|
|
|
if (!Signals.stop && (Limits.ponder || Limits.infinite))
|
2013-05-03 19:03:42 +02:00
|
|
|
{
|
|
|
|
Signals.stopOnPonderhit = true;
|
|
|
|
RootPos.this_thread()->wait_for(Signals.stop);
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// Best move could be MOVE_NONE when searching on a stalemate position
|
2013-05-03 19:03:42 +02:00
|
|
|
sync_cout << "bestmove " << move_to_uci(RootMoves[0].pv[0], RootPos.is_chess960())
|
|
|
|
<< " ponder " << move_to_uci(RootMoves[0].pv[1], RootPos.is_chess960())
|
|
|
|
<< sync_endl;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
namespace {
|
|
|
|
|
|
|
|
// id_loop() is the main iterative deepening loop. It calls search() repeatedly
|
|
|
|
// with increasing depth until the allocated thinking time has been consumed,
|
|
|
|
// user stops the search, or the maximum search depth is reached.
|
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
void id_loop(Position& pos) {
|
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2)
|
2013-11-30 20:12:34 +01:00
|
|
|
int depth;
|
2012-01-01 01:52:19 +01:00
|
|
|
Value bestValue, alpha, beta, delta;
|
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
std::memset(ss-2, 0, 5 * sizeof(Stack));
|
|
|
|
(ss-1)->currentMove = MOVE_NULL; // Hack to skip update gains
|
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
depth = 0;
|
|
|
|
BestMoveChanges = 0;
|
2013-08-20 20:02:33 +02:00
|
|
|
bestValue = delta = alpha = -VALUE_INFINITE;
|
|
|
|
beta = VALUE_INFINITE;
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
TT.new_search();
|
2013-08-20 20:02:33 +02:00
|
|
|
History.clear();
|
|
|
|
Gains.clear();
|
|
|
|
Countermoves.clear();
|
2014-05-31 14:23:03 +02:00
|
|
|
Followupmoves.clear();
|
2013-05-03 19:03:42 +02:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
MultiPV = Options["MultiPV"];
|
2013-05-03 19:03:42 +02:00
|
|
|
Skill skill(Options["Skill Level"]);
|
|
|
|
|
|
|
|
// Do we have to play with skill handicap? In this case enable MultiPV search
|
|
|
|
// that we will use behind the scenes to retrieve a set of possible moves.
|
2014-05-31 14:23:03 +02:00
|
|
|
if (skill.enabled() && MultiPV < 4)
|
|
|
|
MultiPV = 4;
|
2013-05-03 19:03:42 +02:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
MultiPV = std::min(MultiPV, RootMoves.size());
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2011-11-12 20:44:06 +01:00
|
|
|
// Iterative deepening loop until requested to stop or target depth reached
|
2013-05-03 19:03:42 +02:00
|
|
|
while (++depth <= MAX_PLY && !Signals.stop && (!Limits.depth || depth <= Limits.depth))
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-11-30 20:12:34 +01:00
|
|
|
// Age out PV variability metric
|
2014-05-31 14:23:03 +02:00
|
|
|
BestMoveChanges *= 0.5;
|
2013-11-30 20:12:34 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Save the last iteration's scores before first PV line is searched and
|
|
|
|
// all the move scores except the (new) PV are set to -VALUE_INFINITE.
|
2013-11-30 20:12:34 +01:00
|
|
|
for (size_t i = 0; i < RootMoves.size(); ++i)
|
2012-01-01 01:52:19 +01:00
|
|
|
RootMoves[i].prevScore = RootMoves[i].score;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// MultiPV loop. We perform a full root search for each PV line
|
2014-05-31 14:23:03 +02:00
|
|
|
for (PVIdx = 0; PVIdx < MultiPV && !Signals.stop; ++PVIdx)
|
2012-01-01 01:52:19 +01:00
|
|
|
{
|
2013-08-20 20:02:33 +02:00
|
|
|
// Reset aspiration window starting size
|
|
|
|
if (depth >= 5)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-01-01 01:52:19 +01:00
|
|
|
delta = Value(16);
|
2013-08-20 20:02:33 +02:00
|
|
|
alpha = std::max(RootMoves[PVIdx].prevScore - delta,-VALUE_INFINITE);
|
|
|
|
beta = std::min(RootMoves[PVIdx].prevScore + delta, VALUE_INFINITE);
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Start with a small aspiration window and, in the case of a fail
|
|
|
|
// high/low, re-search with a bigger window until we're not failing
|
|
|
|
// high/low anymore.
|
2012-09-16 17:16:15 +02:00
|
|
|
while (true)
|
|
|
|
{
|
2014-05-31 14:23:03 +02:00
|
|
|
bestValue = search<Root, false>(pos, ss, alpha, beta, depth * ONE_PLY, false);
|
|
|
|
|
|
|
|
// Bring the best move to the front. It is critical that sorting
|
|
|
|
// is done with a stable algorithm because all the values but the
|
|
|
|
// first and eventually the new best one are set to -VALUE_INFINITE
|
|
|
|
// and we want to keep the same order for all the moves except the
|
|
|
|
// new PV that goes to the front. Note that in case of MultiPV
|
|
|
|
// search the already searched PV lines are preserved.
|
2013-05-03 19:03:42 +02:00
|
|
|
std::stable_sort(RootMoves.begin() + PVIdx, RootMoves.end());
|
2012-01-01 01:52:19 +01:00
|
|
|
|
|
|
|
// Write PV back to transposition table in case the relevant
|
|
|
|
// entries have been overwritten during the search.
|
2013-11-30 20:12:34 +01:00
|
|
|
for (size_t i = 0; i <= PVIdx; ++i)
|
2012-01-01 01:52:19 +01:00
|
|
|
RootMoves[i].insert_pv_in_tt(pos);
|
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
// If search has been stopped break immediately. Sorting and
|
2014-05-31 14:23:03 +02:00
|
|
|
// writing PV back to TT is safe because RootMoves is still
|
|
|
|
// valid, although it refers to previous iteration.
|
2012-01-01 01:52:19 +01:00
|
|
|
if (Signals.stop)
|
2013-11-30 20:12:34 +01:00
|
|
|
break;
|
2013-05-03 19:03:42 +02:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
// When failing high/low give some update (without cluttering
|
2014-05-31 14:23:03 +02:00
|
|
|
// the UI) before a re-search.
|
2013-08-20 20:02:33 +02:00
|
|
|
if ( (bestValue <= alpha || bestValue >= beta)
|
|
|
|
&& Time::now() - SearchTime > 3000)
|
2012-09-16 17:16:15 +02:00
|
|
|
sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
// In case of failing low/high increase aspiration window and
|
2014-05-31 14:23:03 +02:00
|
|
|
// re-search, otherwise exit the loop.
|
2013-08-20 20:02:33 +02:00
|
|
|
if (bestValue <= alpha)
|
2013-05-03 19:03:42 +02:00
|
|
|
{
|
2013-08-20 20:02:33 +02:00
|
|
|
alpha = std::max(bestValue - delta, -VALUE_INFINITE);
|
|
|
|
|
|
|
|
Signals.failedLowAtRoot = true;
|
|
|
|
Signals.stopOnPonderhit = false;
|
2013-05-03 19:03:42 +02:00
|
|
|
}
|
|
|
|
else if (bestValue >= beta)
|
2013-08-20 20:02:33 +02:00
|
|
|
beta = std::min(bestValue + delta, VALUE_INFINITE);
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
else
|
2013-08-20 20:02:33 +02:00
|
|
|
break;
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
delta += delta / 2;
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
|
|
|
|
}
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
// Sort the PV lines searched so far and update the GUI
|
|
|
|
std::stable_sort(RootMoves.begin(), RootMoves.begin() + PVIdx + 1);
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
if (PVIdx + 1 == MultiPV || Time::now() - SearchTime > 3000)
|
2013-05-03 19:03:42 +02:00
|
|
|
sync_cout << uci_pv(pos, depth, alpha, beta) << sync_endl;
|
2012-01-01 01:52:19 +01:00
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// If skill levels are enabled and time is up, pick a sub-optimal best move
|
2013-05-03 19:03:42 +02:00
|
|
|
if (skill.enabled() && skill.time_to_pick(depth))
|
|
|
|
skill.pick_move();
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
if (Options["Write Search Log"])
|
2012-09-16 17:16:15 +02:00
|
|
|
{
|
2013-08-20 20:02:33 +02:00
|
|
|
RootMove& rm = RootMoves[0];
|
|
|
|
if (skill.best != MOVE_NONE)
|
|
|
|
rm = *std::find(RootMoves.begin(), RootMoves.end(), skill.best);
|
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
Log log(Options["Search Log Filename"]);
|
2013-08-20 20:02:33 +02:00
|
|
|
log << pretty_pv(pos, depth, rm.score, Time::now() - SearchTime, &rm.pv[0])
|
2012-09-16 17:16:15 +02:00
|
|
|
<< std::endl;
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Have we found a "mate in x"?
|
2013-05-03 19:03:42 +02:00
|
|
|
if ( Limits.mate
|
|
|
|
&& bestValue >= VALUE_MATE_IN_MAX_PLY
|
|
|
|
&& VALUE_MATE - bestValue <= 2 * Limits.mate)
|
|
|
|
Signals.stop = true;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// Do we have time for the next iteration? Can we stop searching now?
|
2013-11-30 20:12:34 +01:00
|
|
|
if (Limits.use_time_management() && !Signals.stop && !Signals.stopOnPonderhit)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2014-05-31 14:23:03 +02:00
|
|
|
// Take some extra time if the best move has changed
|
|
|
|
if (depth > 4 && depth < 50 && MultiPV == 1)
|
2013-11-30 20:12:34 +01:00
|
|
|
TimeMgr.pv_instability(BestMoveChanges);
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Stop the search if only one legal move is available or all
|
|
|
|
// of the available time has been used.
|
|
|
|
if ( RootMoves.size() == 1
|
|
|
|
|| Time::now() - SearchTime > TimeMgr.available_time())
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-01-01 01:52:19 +01:00
|
|
|
// If we are allowed to ponder do not stop the search now but
|
2014-05-31 14:23:03 +02:00
|
|
|
// keep pondering until the GUI sends "ponderhit" or "stop".
|
2012-01-01 01:52:19 +01:00
|
|
|
if (Limits.ponder)
|
|
|
|
Signals.stopOnPonderhit = true;
|
|
|
|
else
|
|
|
|
Signals.stop = true;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
// search<>() is the main search function for both PV and non-PV nodes and for
|
|
|
|
// normal and SplitPoint nodes. When called just after a split point the search
|
|
|
|
// is simpler because we have already probed the hash table, done a null move
|
2014-05-31 14:23:03 +02:00
|
|
|
// search, and searched the first move before splitting, so we don't have to
|
|
|
|
// repeat all this work again. We also don't need to store anything to the hash
|
|
|
|
// table here: This is taken care of after we return from the split point.
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
template <NodeType NT, bool SpNode>
|
2013-08-20 20:02:33 +02:00
|
|
|
Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode) {
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
const bool RootNode = NT == Root;
|
|
|
|
const bool PvNode = NT == PV || NT == Root;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE);
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(PvNode || (alpha == beta - 1));
|
2012-01-01 01:52:19 +01:00
|
|
|
assert(depth > DEPTH_ZERO);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
Move quietsSearched[64];
|
2011-11-12 20:44:06 +01:00
|
|
|
StateInfo st;
|
|
|
|
const TTEntry *tte;
|
2013-05-03 19:03:42 +02:00
|
|
|
SplitPoint* splitPoint;
|
2011-11-12 20:44:06 +01:00
|
|
|
Key posKey;
|
2014-05-31 14:23:03 +02:00
|
|
|
Move ttMove, move, excludedMove, bestMove;
|
2013-11-30 20:12:34 +01:00
|
|
|
Depth ext, newDepth, predictedDepth;
|
|
|
|
Value bestValue, value, ttValue, eval, nullValue, futilityValue;
|
2013-08-20 20:02:33 +02:00
|
|
|
bool inCheck, givesCheck, pvMove, singularExtensionNode, improving;
|
2012-01-01 01:52:19 +01:00
|
|
|
bool captureOrPromotion, dangerous, doFullDepthSearch;
|
2013-08-20 20:02:33 +02:00
|
|
|
int moveCount, quietCount;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// Step 1. Initialize node
|
2013-05-03 19:03:42 +02:00
|
|
|
Thread* thisThread = pos.this_thread();
|
|
|
|
inCheck = pos.checkers();
|
|
|
|
|
2012-06-04 18:25:51 +02:00
|
|
|
if (SpNode)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
splitPoint = ss->splitPoint;
|
|
|
|
bestMove = splitPoint->bestMove;
|
|
|
|
bestValue = splitPoint->bestValue;
|
2011-11-12 20:44:06 +01:00
|
|
|
tte = NULL;
|
|
|
|
ttMove = excludedMove = MOVE_NONE;
|
2013-05-03 19:03:42 +02:00
|
|
|
ttValue = VALUE_NONE;
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(splitPoint->bestValue > -VALUE_INFINITE && splitPoint->moveCount > 0);
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
goto moves_loop;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
moveCount = quietCount = 0;
|
2013-05-03 19:03:42 +02:00
|
|
|
bestValue = -VALUE_INFINITE;
|
2014-05-31 14:23:03 +02:00
|
|
|
ss->currentMove = ss->ttMove = (ss+1)->excludedMove = bestMove = MOVE_NONE;
|
2013-05-03 19:03:42 +02:00
|
|
|
ss->ply = (ss-1)->ply + 1;
|
|
|
|
(ss+1)->skipNullMove = false; (ss+1)->reduction = DEPTH_ZERO;
|
|
|
|
(ss+2)->killers[0] = (ss+2)->killers[1] = MOVE_NONE;
|
|
|
|
|
|
|
|
// Used to send selDepth info to GUI
|
|
|
|
if (PvNode && thisThread->maxPly < ss->ply)
|
|
|
|
thisThread->maxPly = ss->ply;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
if (!RootNode)
|
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
// Step 2. Check for aborted search and immediate draw
|
|
|
|
if (Signals.stop || pos.is_draw() || ss->ply > MAX_PLY)
|
2014-05-31 14:23:03 +02:00
|
|
|
return ss->ply > MAX_PLY && !inCheck ? evaluate(pos) : DrawValue[pos.side_to_move()];
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
// Step 3. Mate distance pruning. Even if we mate at the next move our score
|
|
|
|
// would be at best mate_in(ss->ply+1), but if alpha is already bigger because
|
|
|
|
// a shorter mate was found upward in the tree then there is no need to search
|
2014-05-31 14:23:03 +02:00
|
|
|
// because we will never beat the current alpha. Same logic but with reversed
|
|
|
|
// signs applies also in the opposite condition of being mated instead of giving
|
|
|
|
// mate. In this case return a fail-high score.
|
2012-01-01 01:52:19 +01:00
|
|
|
alpha = std::max(mated_in(ss->ply), alpha);
|
|
|
|
beta = std::min(mate_in(ss->ply+1), beta);
|
|
|
|
if (alpha >= beta)
|
|
|
|
return alpha;
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
// Step 4. Transposition table lookup
|
|
|
|
// We don't want the score of a partial search to overwrite a previous full search
|
|
|
|
// TT value, so we use a different position key in case of an excluded move.
|
|
|
|
excludedMove = ss->excludedMove;
|
2012-01-01 01:52:19 +01:00
|
|
|
posKey = excludedMove ? pos.exclusion_key() : pos.key();
|
2011-11-12 20:44:06 +01:00
|
|
|
tte = TT.probe(posKey);
|
2014-05-31 14:23:03 +02:00
|
|
|
ss->ttMove = ttMove = RootNode ? RootMoves[PVIdx].pv[0] : tte ? tte->move() : MOVE_NONE;
|
2013-05-03 19:03:42 +02:00
|
|
|
ttValue = tte ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// At PV nodes we check for exact scores, whilst at non-PV nodes we check for
|
|
|
|
// a fail high/low. The biggest advantage to probing at PV nodes is to have a
|
2012-01-01 01:52:19 +01:00
|
|
|
// smooth experience in analysis mode. We don't probe at Root nodes otherwise
|
|
|
|
// we should also update RootMoveList to avoid bogus output.
|
2013-05-03 19:03:42 +02:00
|
|
|
if ( !RootNode
|
|
|
|
&& tte
|
|
|
|
&& tte->depth() >= depth
|
|
|
|
&& ttValue != VALUE_NONE // Only in case of TT access race
|
2013-08-20 20:02:33 +02:00
|
|
|
&& ( PvNode ? tte->bound() == BOUND_EXACT
|
|
|
|
: ttValue >= beta ? (tte->bound() & BOUND_LOWER)
|
|
|
|
: (tte->bound() & BOUND_UPPER)))
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-06-04 18:25:51 +02:00
|
|
|
ss->currentMove = ttMove; // Can be MOVE_NONE
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// If ttMove is quiet, update killers, history, counter move and followup move on TT hit
|
|
|
|
if (ttValue >= beta && ttMove && !pos.capture_or_promotion(ttMove) && !inCheck)
|
|
|
|
update_stats(pos, ss, ttMove, depth, NULL, 0);
|
|
|
|
|
2012-06-04 18:25:51 +02:00
|
|
|
return ttValue;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
// Step 5. Evaluate the position statically and update parent's gain statistics
|
|
|
|
if (inCheck)
|
2013-08-20 20:02:33 +02:00
|
|
|
{
|
2013-11-30 20:12:34 +01:00
|
|
|
ss->staticEval = eval = VALUE_NONE;
|
2013-08-20 20:02:33 +02:00
|
|
|
goto moves_loop;
|
|
|
|
}
|
2013-05-03 19:03:42 +02:00
|
|
|
|
2011-11-12 20:44:06 +01:00
|
|
|
else if (tte)
|
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
// Never assume anything on values stored in TT
|
2013-11-30 20:12:34 +01:00
|
|
|
if ((ss->staticEval = eval = tte->eval_value()) == VALUE_NONE)
|
|
|
|
eval = ss->staticEval = evaluate(pos);
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
// Can ttValue be used as a better position evaluation?
|
|
|
|
if (ttValue != VALUE_NONE)
|
2013-11-30 20:12:34 +01:00
|
|
|
if (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER))
|
2013-05-03 19:03:42 +02:00
|
|
|
eval = ttValue;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
else
|
|
|
|
{
|
2013-11-30 20:12:34 +01:00
|
|
|
eval = ss->staticEval = evaluate(pos);
|
|
|
|
TT.store(posKey, VALUE_NONE, BOUND_NONE, DEPTH_NONE, MOVE_NONE, ss->staticEval);
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
if ( !pos.captured_piece_type()
|
2013-05-03 19:03:42 +02:00
|
|
|
&& ss->staticEval != VALUE_NONE
|
2013-08-20 20:02:33 +02:00
|
|
|
&& (ss-1)->staticEval != VALUE_NONE
|
|
|
|
&& (move = (ss-1)->currentMove) != MOVE_NULL
|
2012-09-16 17:16:15 +02:00
|
|
|
&& type_of(move) == NORMAL)
|
2012-01-01 01:52:19 +01:00
|
|
|
{
|
2012-01-07 03:07:28 +01:00
|
|
|
Square to = to_sq(move);
|
2013-08-20 20:02:33 +02:00
|
|
|
Gains.update(pos.piece_on(to), to, -(ss-1)->staticEval - ss->staticEval);
|
2012-01-01 01:52:19 +01:00
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
// Step 6. Razoring (skipped when in check)
|
2011-11-12 20:44:06 +01:00
|
|
|
if ( !PvNode
|
2013-05-03 19:03:42 +02:00
|
|
|
&& depth < 4 * ONE_PLY
|
2014-05-31 14:23:03 +02:00
|
|
|
&& eval + razor_margin(depth) <= alpha
|
2011-11-12 20:44:06 +01:00
|
|
|
&& ttMove == MOVE_NONE
|
2012-01-01 01:52:19 +01:00
|
|
|
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
|
2012-06-04 18:25:51 +02:00
|
|
|
&& !pos.pawn_on_7th(pos.side_to_move()))
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2014-05-31 14:23:03 +02:00
|
|
|
if ( depth <= ONE_PLY
|
|
|
|
&& eval + razor_margin(3 * ONE_PLY) <= alpha)
|
|
|
|
return qsearch<NonPV, false>(pos, ss, alpha, beta, DEPTH_ZERO);
|
|
|
|
|
|
|
|
Value ralpha = alpha - razor_margin(depth);
|
|
|
|
Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1, DEPTH_ZERO);
|
|
|
|
if (v <= ralpha)
|
2011-11-12 20:44:06 +01:00
|
|
|
return v;
|
|
|
|
}
|
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
// Step 7. Futility pruning: child node (skipped when in check)
|
2011-11-12 20:44:06 +01:00
|
|
|
if ( !PvNode
|
|
|
|
&& !ss->skipNullMove
|
2013-11-30 20:12:34 +01:00
|
|
|
&& depth < 7 * ONE_PLY
|
|
|
|
&& eval - futility_margin(depth) >= beta
|
2012-01-01 01:52:19 +01:00
|
|
|
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
|
2013-05-03 19:03:42 +02:00
|
|
|
&& abs(eval) < VALUE_KNOWN_WIN
|
2011-11-12 20:44:06 +01:00
|
|
|
&& pos.non_pawn_material(pos.side_to_move()))
|
2013-11-30 20:12:34 +01:00
|
|
|
return eval - futility_margin(depth);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
// Step 8. Null move search with verification search (is omitted in PV nodes)
|
|
|
|
if ( !PvNode
|
|
|
|
&& !ss->skipNullMove
|
2013-11-30 20:12:34 +01:00
|
|
|
&& depth >= 2 * ONE_PLY
|
2013-05-03 19:03:42 +02:00
|
|
|
&& eval >= beta
|
2012-01-01 01:52:19 +01:00
|
|
|
&& abs(beta) < VALUE_MATE_IN_MAX_PLY
|
2011-11-12 20:44:06 +01:00
|
|
|
&& pos.non_pawn_material(pos.side_to_move()))
|
|
|
|
{
|
|
|
|
ss->currentMove = MOVE_NULL;
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
assert(eval - beta >= 0);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Null move dynamic reduction based on depth and value
|
|
|
|
Depth R = 3 * ONE_PLY
|
|
|
|
+ depth / 4
|
|
|
|
+ int(eval - beta) / PawnValueMg * ONE_PLY;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
pos.do_null_move(st);
|
2011-11-12 20:44:06 +01:00
|
|
|
(ss+1)->skipNullMove = true;
|
2014-05-31 14:23:03 +02:00
|
|
|
nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1, DEPTH_ZERO)
|
|
|
|
: - search<NonPV, false>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode);
|
2011-11-12 20:44:06 +01:00
|
|
|
(ss+1)->skipNullMove = false;
|
2013-05-03 19:03:42 +02:00
|
|
|
pos.undo_null_move();
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
if (nullValue >= beta)
|
|
|
|
{
|
|
|
|
// Do not return unproven mate scores
|
2012-01-01 01:52:19 +01:00
|
|
|
if (nullValue >= VALUE_MATE_IN_MAX_PLY)
|
2011-11-12 20:44:06 +01:00
|
|
|
nullValue = beta;
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
if (depth < 12 * ONE_PLY)
|
2011-11-12 20:44:06 +01:00
|
|
|
return nullValue;
|
|
|
|
|
|
|
|
// Do verification search at high depths
|
|
|
|
ss->skipNullMove = true;
|
2014-05-31 14:23:03 +02:00
|
|
|
Value v = depth-R < ONE_PLY ? qsearch<NonPV, false>(pos, ss, beta-1, beta, DEPTH_ZERO)
|
|
|
|
: search<NonPV, false>(pos, ss, beta-1, beta, depth-R, false);
|
2011-11-12 20:44:06 +01:00
|
|
|
ss->skipNullMove = false;
|
|
|
|
|
|
|
|
if (v >= beta)
|
|
|
|
return nullValue;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
// Step 9. ProbCut (skipped when in check)
|
2012-01-01 01:52:19 +01:00
|
|
|
// If we have a very good capture (i.e. SEE > seeValues[captured_piece_type])
|
|
|
|
// and a reduced search returns a value much above beta, we can (almost) safely
|
|
|
|
// prune the previous move.
|
|
|
|
if ( !PvNode
|
2013-05-03 19:03:42 +02:00
|
|
|
&& depth >= 5 * ONE_PLY
|
2012-01-01 01:52:19 +01:00
|
|
|
&& !ss->skipNullMove
|
|
|
|
&& abs(beta) < VALUE_MATE_IN_MAX_PLY)
|
|
|
|
{
|
2014-05-31 14:23:03 +02:00
|
|
|
Value rbeta = std::min(beta + 200, VALUE_INFINITE);
|
|
|
|
Depth rdepth = depth - 4 * ONE_PLY;
|
2012-01-01 01:52:19 +01:00
|
|
|
|
|
|
|
assert(rdepth >= ONE_PLY);
|
2012-06-04 18:25:51 +02:00
|
|
|
assert((ss-1)->currentMove != MOVE_NONE);
|
|
|
|
assert((ss-1)->currentMove != MOVE_NULL);
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
MovePicker mp(pos, ttMove, History, pos.captured_piece_type());
|
2012-01-01 01:52:19 +01:00
|
|
|
CheckInfo ci(pos);
|
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
while ((move = mp.next_move<false>()) != MOVE_NONE)
|
2013-11-30 20:12:34 +01:00
|
|
|
if (pos.legal(move, ci.pinned))
|
2012-01-01 01:52:19 +01:00
|
|
|
{
|
2012-06-04 18:25:51 +02:00
|
|
|
ss->currentMove = move;
|
2013-11-30 20:12:34 +01:00
|
|
|
pos.do_move(move, st, ci, pos.gives_check(move, ci));
|
2014-05-31 14:23:03 +02:00
|
|
|
value = -search<NonPV, false>(pos, ss+1, -rbeta, -rbeta+1, rdepth, !cutNode);
|
2012-01-01 01:52:19 +01:00
|
|
|
pos.undo_move(move);
|
|
|
|
if (value >= rbeta)
|
|
|
|
return value;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
// Step 10. Internal iterative deepening (skipped when in check)
|
2014-05-31 14:23:03 +02:00
|
|
|
if ( depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY)
|
|
|
|
&& !ttMove
|
|
|
|
&& (PvNode || ss->staticEval + 256 >= beta))
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
Depth d = depth - 2 * ONE_PLY - (PvNode ? DEPTH_ZERO : depth / 4);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
ss->skipNullMove = true;
|
2014-05-31 14:23:03 +02:00
|
|
|
search<PvNode ? PV : NonPV, false>(pos, ss, alpha, beta, d, true);
|
2011-11-12 20:44:06 +01:00
|
|
|
ss->skipNullMove = false;
|
|
|
|
|
|
|
|
tte = TT.probe(posKey);
|
2012-01-01 01:52:19 +01:00
|
|
|
ttMove = tte ? tte->move() : MOVE_NONE;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
moves_loop: // When in check and at SpNode search starts from here
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
Square prevMoveSq = to_sq((ss-1)->currentMove);
|
|
|
|
Move countermoves[] = { Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].first,
|
|
|
|
Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].second };
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
Square prevOwnMoveSq = to_sq((ss-2)->currentMove);
|
|
|
|
Move followupmoves[] = { Followupmoves[pos.piece_on(prevOwnMoveSq)][prevOwnMoveSq].first,
|
|
|
|
Followupmoves[pos.piece_on(prevOwnMoveSq)][prevOwnMoveSq].second };
|
|
|
|
|
|
|
|
MovePicker mp(pos, ttMove, depth, History, countermoves, followupmoves, ss);
|
2011-11-12 20:44:06 +01:00
|
|
|
CheckInfo ci(pos);
|
2013-05-03 19:03:42 +02:00
|
|
|
value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
|
2013-08-20 20:02:33 +02:00
|
|
|
improving = ss->staticEval >= (ss-2)->staticEval
|
|
|
|
|| ss->staticEval == VALUE_NONE
|
|
|
|
||(ss-2)->staticEval == VALUE_NONE;
|
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
singularExtensionNode = !RootNode
|
2011-11-12 20:44:06 +01:00
|
|
|
&& !SpNode
|
2013-11-30 20:12:34 +01:00
|
|
|
&& depth >= 8 * ONE_PLY
|
2012-06-04 18:25:51 +02:00
|
|
|
&& ttMove != MOVE_NONE
|
2012-01-01 01:52:19 +01:00
|
|
|
&& !excludedMove // Recursive singular search is not allowed
|
2013-08-20 20:02:33 +02:00
|
|
|
&& (tte->bound() & BOUND_LOWER)
|
2012-06-04 18:25:51 +02:00
|
|
|
&& tte->depth() >= depth - 3 * ONE_PLY;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// Step 11. Loop through moves
|
|
|
|
// Loop through all pseudo-legal moves until no moves remain or a beta cutoff occurs
|
2013-05-03 19:03:42 +02:00
|
|
|
while ((move = mp.next_move<SpNode>()) != MOVE_NONE)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-01-01 01:52:19 +01:00
|
|
|
assert(is_ok(move));
|
|
|
|
|
|
|
|
if (move == excludedMove)
|
|
|
|
continue;
|
|
|
|
|
|
|
|
// At root obey the "searchmoves" option and skip moves not listed in Root
|
2014-05-31 14:23:03 +02:00
|
|
|
// Move List. As a consequence any illegal move is also skipped. In MultiPV
|
2012-01-01 01:52:19 +01:00
|
|
|
// mode we also skip PV moves which have been already searched.
|
2012-09-16 17:16:15 +02:00
|
|
|
if (RootNode && !std::count(RootMoves.begin() + PVIdx, RootMoves.end(), move))
|
2012-01-01 01:52:19 +01:00
|
|
|
continue;
|
|
|
|
|
2011-11-12 20:44:06 +01:00
|
|
|
if (SpNode)
|
|
|
|
{
|
2014-05-31 14:23:03 +02:00
|
|
|
// Shared counter cannot be decremented later if the move turns out to be illegal
|
2013-11-30 20:12:34 +01:00
|
|
|
if (!pos.legal(move, ci.pinned))
|
2013-05-03 19:03:42 +02:00
|
|
|
continue;
|
|
|
|
|
|
|
|
moveCount = ++splitPoint->moveCount;
|
|
|
|
splitPoint->mutex.unlock();
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
else
|
2013-11-30 20:12:34 +01:00
|
|
|
++moveCount;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
if (RootNode)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-01-01 01:52:19 +01:00
|
|
|
Signals.firstRootMove = (moveCount == 1);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
if (thisThread == Threads.main() && Time::now() - SearchTime > 3000)
|
2012-09-16 17:16:15 +02:00
|
|
|
sync_cout << "info depth " << depth / ONE_PLY
|
2013-05-03 19:03:42 +02:00
|
|
|
<< " currmove " << move_to_uci(move, pos.is_chess960())
|
2012-09-16 17:16:15 +02:00
|
|
|
<< " currmovenumber " << moveCount + PVIdx << sync_endl;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
ext = DEPTH_ZERO;
|
2013-11-30 20:12:34 +01:00
|
|
|
captureOrPromotion = pos.capture_or_promotion(move);
|
2014-05-31 14:23:03 +02:00
|
|
|
|
|
|
|
givesCheck = type_of(move) == NORMAL && !ci.dcCandidates
|
|
|
|
? ci.checkSq[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
|
|
|
|
: pos.gives_check(move, ci);
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
dangerous = givesCheck
|
2014-05-31 14:23:03 +02:00
|
|
|
|| type_of(move) != NORMAL
|
|
|
|
|| pos.advanced_pawn_push(move);
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
// Step 12. Extend checks
|
2014-05-31 14:23:03 +02:00
|
|
|
if (givesCheck && pos.see_sign(move) >= VALUE_ZERO)
|
2012-01-01 01:52:19 +01:00
|
|
|
ext = ONE_PLY;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
// Singular extension search. If all moves but one fail low on a search of
|
|
|
|
// (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move
|
|
|
|
// is singular and should be extended. To verify this we do a reduced search
|
2014-05-31 14:23:03 +02:00
|
|
|
// on all the other moves but the ttMove and if the result is lower than
|
|
|
|
// ttValue minus a margin then we extend the ttMove.
|
2012-06-04 18:25:51 +02:00
|
|
|
if ( singularExtensionNode
|
|
|
|
&& move == ttMove
|
2013-05-03 19:03:42 +02:00
|
|
|
&& !ext
|
2013-11-30 20:12:34 +01:00
|
|
|
&& pos.legal(move, ci.pinned)
|
2012-09-16 17:16:15 +02:00
|
|
|
&& abs(ttValue) < VALUE_KNOWN_WIN)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(ttValue != VALUE_NONE);
|
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
Value rBeta = ttValue - int(depth);
|
|
|
|
ss->excludedMove = move;
|
|
|
|
ss->skipNullMove = true;
|
2014-05-31 14:23:03 +02:00
|
|
|
value = search<NonPV, false>(pos, ss, rBeta - 1, rBeta, depth / 2, cutNode);
|
2012-09-16 17:16:15 +02:00
|
|
|
ss->skipNullMove = false;
|
|
|
|
ss->excludedMove = MOVE_NONE;
|
|
|
|
|
|
|
|
if (value < rBeta)
|
|
|
|
ext = ONE_PLY;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Update the current move (this must be done after singular extension search)
|
2011-11-12 20:44:06 +01:00
|
|
|
newDepth = depth - ONE_PLY + ext;
|
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
// Step 13. Pruning at shallow depth (exclude PV nodes)
|
2011-11-12 20:44:06 +01:00
|
|
|
if ( !PvNode
|
|
|
|
&& !captureOrPromotion
|
|
|
|
&& !inCheck
|
|
|
|
&& !dangerous
|
2013-05-03 19:03:42 +02:00
|
|
|
/* && move != ttMove Already implicit in the next condition */
|
|
|
|
&& bestValue > VALUE_MATED_IN_MAX_PLY)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
|
|
|
// Move count based pruning
|
2013-05-03 19:03:42 +02:00
|
|
|
if ( depth < 16 * ONE_PLY
|
2014-05-31 14:23:03 +02:00
|
|
|
&& moveCount >= FutilityMoveCounts[improving][depth] )
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
|
|
|
if (SpNode)
|
2013-05-03 19:03:42 +02:00
|
|
|
splitPoint->mutex.lock();
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
predictedDepth = newDepth - reduction<PvNode>(improving, depth, moveCount);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
// Futility pruning: parent node
|
|
|
|
if (predictedDepth < 7 * ONE_PLY)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-11-30 20:12:34 +01:00
|
|
|
futilityValue = ss->staticEval + futility_margin(predictedDepth)
|
2014-05-31 14:23:03 +02:00
|
|
|
+ 128 + Gains[pos.moved_piece(move)][to_sq(move)];
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
if (futilityValue <= alpha)
|
2013-05-03 19:03:42 +02:00
|
|
|
{
|
2013-11-30 20:12:34 +01:00
|
|
|
bestValue = std::max(bestValue, futilityValue);
|
|
|
|
|
|
|
|
if (SpNode)
|
|
|
|
{
|
|
|
|
splitPoint->mutex.lock();
|
|
|
|
if (bestValue > splitPoint->bestValue)
|
|
|
|
splitPoint->bestValue = bestValue;
|
|
|
|
}
|
|
|
|
continue;
|
2013-05-03 19:03:42 +02:00
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
// Prune moves with negative SEE at low depths
|
2014-05-31 14:23:03 +02:00
|
|
|
if (predictedDepth < 4 * ONE_PLY && pos.see_sign(move) < VALUE_ZERO)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
|
|
|
if (SpNode)
|
2013-05-03 19:03:42 +02:00
|
|
|
splitPoint->mutex.lock();
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Check for legality just before making the move
|
2013-11-30 20:12:34 +01:00
|
|
|
if (!RootNode && !SpNode && !pos.legal(move, ci.pinned))
|
2012-01-01 01:52:19 +01:00
|
|
|
{
|
|
|
|
moveCount--;
|
|
|
|
continue;
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
pvMove = PvNode && moveCount == 1;
|
2012-01-01 01:52:19 +01:00
|
|
|
ss->currentMove = move;
|
2013-08-20 20:02:33 +02:00
|
|
|
if (!SpNode && !captureOrPromotion && quietCount < 64)
|
|
|
|
quietsSearched[quietCount++] = move;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// Step 14. Make the move
|
|
|
|
pos.do_move(move, st, ci, givesCheck);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Step 15. Reduced depth search (LMR). If the move fails high it will be
|
2012-01-01 01:52:19 +01:00
|
|
|
// re-searched at full depth.
|
2013-11-30 20:12:34 +01:00
|
|
|
if ( depth >= 3 * ONE_PLY
|
2013-05-03 19:03:42 +02:00
|
|
|
&& !pvMove
|
2012-01-01 01:52:19 +01:00
|
|
|
&& !captureOrPromotion
|
2013-05-03 19:03:42 +02:00
|
|
|
&& move != ttMove
|
|
|
|
&& move != ss->killers[0]
|
|
|
|
&& move != ss->killers[1])
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-08-20 20:02:33 +02:00
|
|
|
ss->reduction = reduction<PvNode>(improving, depth, moveCount);
|
|
|
|
|
|
|
|
if (!PvNode && cutNode)
|
|
|
|
ss->reduction += ONE_PLY;
|
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
else if (History[pos.piece_on(to_sq(move))][to_sq(move)] < 0)
|
|
|
|
ss->reduction += ONE_PLY / 2;
|
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
if (move == countermoves[0] || move == countermoves[1])
|
2013-11-30 20:12:34 +01:00
|
|
|
ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
|
2013-08-20 20:02:33 +02:00
|
|
|
|
2012-06-04 18:25:51 +02:00
|
|
|
Depth d = std::max(newDepth - ss->reduction, ONE_PLY);
|
2013-05-03 19:03:42 +02:00
|
|
|
if (SpNode)
|
|
|
|
alpha = splitPoint->alpha;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
value = -search<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, d, true);
|
|
|
|
|
|
|
|
// Re-search at intermediate depth if reduction is very high
|
|
|
|
if (value > alpha && ss->reduction >= 4 * ONE_PLY)
|
|
|
|
{
|
|
|
|
Depth d2 = std::max(newDepth - 2 * ONE_PLY, ONE_PLY);
|
|
|
|
value = -search<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, d2, true);
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
doFullDepthSearch = (value > alpha && ss->reduction != DEPTH_ZERO);
|
|
|
|
ss->reduction = DEPTH_ZERO;
|
|
|
|
}
|
|
|
|
else
|
2013-05-03 19:03:42 +02:00
|
|
|
doFullDepthSearch = !pvMove;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// Step 16. Full depth search, when LMR is skipped or fails high
|
|
|
|
if (doFullDepthSearch)
|
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
if (SpNode)
|
|
|
|
alpha = splitPoint->alpha;
|
|
|
|
|
|
|
|
value = newDepth < ONE_PLY ?
|
|
|
|
givesCheck ? -qsearch<NonPV, true>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
|
|
|
|
: -qsearch<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, DEPTH_ZERO)
|
2014-05-31 14:23:03 +02:00
|
|
|
: - search<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, newDepth, !cutNode);
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// For PV nodes only, do a full PV search on the first move or after a fail
|
|
|
|
// high (in the latter case search only if value < beta), otherwise let the
|
|
|
|
// parent node fail low with value <= alpha and to try another move.
|
2013-05-03 19:03:42 +02:00
|
|
|
if (PvNode && (pvMove || (value > alpha && (RootNode || value < beta))))
|
|
|
|
value = newDepth < ONE_PLY ?
|
|
|
|
givesCheck ? -qsearch<PV, true>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
|
|
|
|
: -qsearch<PV, false>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
|
2014-05-31 14:23:03 +02:00
|
|
|
: - search<PV, false>(pos, ss+1, -beta, -alpha, newDepth, false);
|
2012-01-01 01:52:19 +01:00
|
|
|
// Step 17. Undo move
|
2011-11-12 20:44:06 +01:00
|
|
|
pos.undo_move(move);
|
|
|
|
|
|
|
|
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
|
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// Step 18. Check for new best move
|
2011-11-12 20:44:06 +01:00
|
|
|
if (SpNode)
|
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
splitPoint->mutex.lock();
|
|
|
|
bestValue = splitPoint->bestValue;
|
|
|
|
alpha = splitPoint->alpha;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Finished searching the move. If a stop or a cutoff occurred, the return
|
|
|
|
// value of the search cannot be trusted, and we return immediately without
|
|
|
|
// updating best move, PV and TT.
|
2013-05-03 19:03:42 +02:00
|
|
|
if (Signals.stop || thisThread->cutoff_occurred())
|
2014-05-31 14:23:03 +02:00
|
|
|
return VALUE_ZERO;
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
if (RootNode)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-09-16 17:16:15 +02:00
|
|
|
RootMove& rm = *std::find(RootMoves.begin(), RootMoves.end(), move);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
// PV move or new best move ?
|
2013-05-03 19:03:42 +02:00
|
|
|
if (pvMove || value > alpha)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-01-01 01:52:19 +01:00
|
|
|
rm.score = value;
|
|
|
|
rm.extract_pv_from_tt(pos);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
// We record how often the best move has been changed in each
|
|
|
|
// iteration. This information is used for time management: When
|
|
|
|
// the best move changes frequently, we allocate some more time.
|
2013-05-03 19:03:42 +02:00
|
|
|
if (!pvMove)
|
2013-11-30 20:12:34 +01:00
|
|
|
++BestMoveChanges;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
else
|
2014-05-31 14:23:03 +02:00
|
|
|
// All other moves but the PV are set to the lowest value: this is
|
|
|
|
// not a problem when sorting because the sort is stable and the
|
|
|
|
// move position in the list is preserved - just the PV is pushed up.
|
2012-01-01 01:52:19 +01:00
|
|
|
rm.score = -VALUE_INFINITE;
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
if (value > bestValue)
|
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
bestValue = SpNode ? splitPoint->bestValue = value : value;
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
if (value > alpha)
|
2012-01-01 01:52:19 +01:00
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
bestMove = SpNode ? splitPoint->bestMove = move : move;
|
|
|
|
|
|
|
|
if (PvNode && value < beta) // Update alpha! Always alpha < beta
|
|
|
|
alpha = SpNode ? splitPoint->alpha = value : value;
|
|
|
|
else
|
|
|
|
{
|
|
|
|
assert(value >= beta); // Fail high
|
|
|
|
|
|
|
|
if (SpNode)
|
|
|
|
splitPoint->cutoff = true;
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
break;
|
|
|
|
}
|
2012-01-01 01:52:19 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
// Step 19. Check for splitting the search
|
2012-01-01 01:52:19 +01:00
|
|
|
if ( !SpNode
|
2014-05-31 14:23:03 +02:00
|
|
|
&& Threads.size() >= 2
|
2013-05-03 19:03:42 +02:00
|
|
|
&& depth >= Threads.minimumSplitDepth
|
2014-05-31 14:23:03 +02:00
|
|
|
&& ( !thisThread->activeSplitPoint
|
|
|
|
|| !thisThread->activeSplitPoint->allSlavesSearching)
|
2013-05-03 19:03:42 +02:00
|
|
|
&& thisThread->splitPointsSize < MAX_SPLITPOINTS_PER_THREAD)
|
|
|
|
{
|
2014-05-31 14:23:03 +02:00
|
|
|
assert(bestValue > -VALUE_INFINITE && bestValue < beta);
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
thisThread->split<FakeSplit>(pos, ss, alpha, beta, &bestValue, &bestMove,
|
2014-05-31 14:23:03 +02:00
|
|
|
depth, moveCount, &mp, NT, cutNode);
|
|
|
|
|
|
|
|
if (Signals.stop || thisThread->cutoff_occurred())
|
|
|
|
return VALUE_ZERO;
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
if (bestValue >= beta)
|
|
|
|
break;
|
|
|
|
}
|
2012-01-01 01:52:19 +01:00
|
|
|
}
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
if (SpNode)
|
|
|
|
return bestValue;
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Following condition would detect a stop or a cutoff set only after move
|
|
|
|
// loop has been completed. But in this case bestValue is valid because we
|
|
|
|
// have fully searched our subtree, and we can anyhow save the result in TT.
|
|
|
|
/*
|
|
|
|
if (Signals.stop || thisThread->cutoff_occurred())
|
|
|
|
return VALUE_DRAW;
|
|
|
|
*/
|
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// Step 20. Check for mate and stalemate
|
|
|
|
// All legal moves have been searched and if there are no legal moves, it
|
2014-05-31 14:23:03 +02:00
|
|
|
// must be mate or stalemate. If we are in a singular extension search then
|
|
|
|
// return a fail low score.
|
2012-01-01 01:52:19 +01:00
|
|
|
if (!moveCount)
|
2014-05-31 14:23:03 +02:00
|
|
|
bestValue = excludedMove ? alpha
|
|
|
|
: inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Quiet best move: update killers, history, countermoves and followupmoves
|
|
|
|
else if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck)
|
|
|
|
update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
TT.store(posKey, value_to_tt(bestValue, ss->ply),
|
|
|
|
bestValue >= beta ? BOUND_LOWER :
|
|
|
|
PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
|
2013-11-30 20:12:34 +01:00
|
|
|
depth, bestMove, ss->staticEval);
|
2013-08-20 20:02:33 +02:00
|
|
|
|
2011-11-12 20:44:06 +01:00
|
|
|
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
|
|
|
|
|
|
|
|
return bestValue;
|
|
|
|
}
|
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2011-11-12 20:44:06 +01:00
|
|
|
// qsearch() is the quiescence search function, which is called by the main
|
|
|
|
// search function when the remaining depth is zero (or, to be more precise,
|
|
|
|
// less than ONE_PLY).
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
template <NodeType NT, bool InCheck>
|
2012-01-01 01:52:19 +01:00
|
|
|
Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
const bool PvNode = NT == PV;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
assert(NT == PV || NT == NonPV);
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(InCheck == !!pos.checkers());
|
2012-01-01 01:52:19 +01:00
|
|
|
assert(alpha >= -VALUE_INFINITE && alpha < beta && beta <= VALUE_INFINITE);
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(PvNode || (alpha == beta - 1));
|
2012-01-01 01:52:19 +01:00
|
|
|
assert(depth <= DEPTH_ZERO);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
StateInfo st;
|
|
|
|
const TTEntry* tte;
|
2013-05-03 19:03:42 +02:00
|
|
|
Key posKey;
|
|
|
|
Move ttMove, move, bestMove;
|
|
|
|
Value bestValue, value, ttValue, futilityValue, futilityBase, oldAlpha;
|
2013-08-20 20:02:33 +02:00
|
|
|
bool givesCheck, evasionPrunable;
|
2011-11-12 20:44:06 +01:00
|
|
|
Depth ttDepth;
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
// To flag BOUND_EXACT a node with eval above alpha and no available moves
|
|
|
|
if (PvNode)
|
|
|
|
oldAlpha = alpha;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-06-04 18:25:51 +02:00
|
|
|
ss->currentMove = bestMove = MOVE_NONE;
|
2011-11-12 20:44:06 +01:00
|
|
|
ss->ply = (ss-1)->ply + 1;
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Check for an instant draw or if the maximum ply has been reached
|
2013-05-03 19:03:42 +02:00
|
|
|
if (pos.is_draw() || ss->ply > MAX_PLY)
|
2014-05-31 14:23:03 +02:00
|
|
|
return ss->ply > MAX_PLY && !InCheck ? evaluate(pos) : DrawValue[pos.side_to_move()];
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Decide whether or not to include checks: this fixes also the type of
|
2011-11-12 20:44:06 +01:00
|
|
|
// TT entry depth that we are going to use. Note that in qsearch we use
|
|
|
|
// only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
|
2013-05-03 19:03:42 +02:00
|
|
|
ttDepth = InCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS
|
|
|
|
: DEPTH_QS_NO_CHECKS;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
// Transposition table lookup
|
2013-05-03 19:03:42 +02:00
|
|
|
posKey = pos.key();
|
|
|
|
tte = TT.probe(posKey);
|
|
|
|
ttMove = tte ? tte->move() : MOVE_NONE;
|
|
|
|
ttValue = tte ? value_from_tt(tte->value(),ss->ply) : VALUE_NONE;
|
|
|
|
|
|
|
|
if ( tte
|
|
|
|
&& tte->depth() >= ttDepth
|
|
|
|
&& ttValue != VALUE_NONE // Only in case of TT access race
|
2013-08-20 20:02:33 +02:00
|
|
|
&& ( PvNode ? tte->bound() == BOUND_EXACT
|
|
|
|
: ttValue >= beta ? (tte->bound() & BOUND_LOWER)
|
|
|
|
: (tte->bound() & BOUND_UPPER)))
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-06-04 18:25:51 +02:00
|
|
|
ss->currentMove = ttMove; // Can be MOVE_NONE
|
|
|
|
return ttValue;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
// Evaluate the position statically
|
2013-05-03 19:03:42 +02:00
|
|
|
if (InCheck)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-11-30 20:12:34 +01:00
|
|
|
ss->staticEval = VALUE_NONE;
|
2011-11-12 20:44:06 +01:00
|
|
|
bestValue = futilityBase = -VALUE_INFINITE;
|
|
|
|
}
|
|
|
|
else
|
|
|
|
{
|
|
|
|
if (tte)
|
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
// Never assume anything on values stored in TT
|
2013-11-30 20:12:34 +01:00
|
|
|
if ((ss->staticEval = bestValue = tte->eval_value()) == VALUE_NONE)
|
|
|
|
ss->staticEval = bestValue = evaluate(pos);
|
|
|
|
|
|
|
|
// Can ttValue be used as a better position evaluation?
|
|
|
|
if (ttValue != VALUE_NONE)
|
|
|
|
if (tte->bound() & (ttValue > bestValue ? BOUND_LOWER : BOUND_UPPER))
|
|
|
|
bestValue = ttValue;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
else
|
2013-11-30 20:12:34 +01:00
|
|
|
ss->staticEval = bestValue = evaluate(pos);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
// Stand pat. Return immediately if static value is at least beta
|
|
|
|
if (bestValue >= beta)
|
|
|
|
{
|
|
|
|
if (!tte)
|
2013-05-03 19:03:42 +02:00
|
|
|
TT.store(pos.key(), value_to_tt(bestValue, ss->ply), BOUND_LOWER,
|
2013-11-30 20:12:34 +01:00
|
|
|
DEPTH_NONE, MOVE_NONE, ss->staticEval);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
return bestValue;
|
|
|
|
}
|
|
|
|
|
|
|
|
if (PvNode && bestValue > alpha)
|
|
|
|
alpha = bestValue;
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
futilityBase = bestValue + 128;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
// Initialize a MovePicker object for the current position, and prepare
|
|
|
|
// to search the moves. Because the depth is <= 0 here, only captures,
|
|
|
|
// queen promotions and checks (only if depth >= DEPTH_QS_CHECKS) will
|
|
|
|
// be generated.
|
2013-08-20 20:02:33 +02:00
|
|
|
MovePicker mp(pos, ttMove, depth, History, to_sq((ss-1)->currentMove));
|
2011-11-12 20:44:06 +01:00
|
|
|
CheckInfo ci(pos);
|
|
|
|
|
|
|
|
// Loop through the moves until no moves remain or a beta cutoff occurs
|
2013-05-03 19:03:42 +02:00
|
|
|
while ((move = mp.next_move<false>()) != MOVE_NONE)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-01-01 01:52:19 +01:00
|
|
|
assert(is_ok(move));
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
givesCheck = type_of(move) == NORMAL && !ci.dcCandidates
|
|
|
|
? ci.checkSq[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
|
|
|
|
: pos.gives_check(move, ci);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
// Futility pruning
|
|
|
|
if ( !PvNode
|
2013-05-03 19:03:42 +02:00
|
|
|
&& !InCheck
|
2011-11-12 20:44:06 +01:00
|
|
|
&& !givesCheck
|
|
|
|
&& move != ttMove
|
2013-11-30 20:12:34 +01:00
|
|
|
&& futilityBase > -VALUE_KNOWN_WIN
|
2014-05-31 14:23:03 +02:00
|
|
|
&& !pos.advanced_pawn_push(move))
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2014-05-31 14:23:03 +02:00
|
|
|
assert(type_of(move) != ENPASSANT); // Due to !pos.advanced_pawn_push
|
|
|
|
|
|
|
|
futilityValue = futilityBase + PieceValue[EG][pos.piece_on(to_sq(move))];
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
if (futilityValue < beta)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
bestValue = std::max(bestValue, futilityValue);
|
2011-11-12 20:44:06 +01:00
|
|
|
continue;
|
|
|
|
}
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
if (futilityBase < beta && pos.see(move) <= VALUE_ZERO)
|
2013-05-03 19:03:42 +02:00
|
|
|
{
|
|
|
|
bestValue = std::max(bestValue, futilityBase);
|
2011-11-12 20:44:06 +01:00
|
|
|
continue;
|
2013-05-03 19:03:42 +02:00
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Detect non-capture evasions that are candidates to be pruned
|
2013-08-20 20:02:33 +02:00
|
|
|
evasionPrunable = InCheck
|
2012-06-04 18:25:51 +02:00
|
|
|
&& bestValue > VALUE_MATED_IN_MAX_PLY
|
2013-11-30 20:12:34 +01:00
|
|
|
&& !pos.capture(move)
|
2011-11-12 20:44:06 +01:00
|
|
|
&& !pos.can_castle(pos.side_to_move());
|
|
|
|
|
|
|
|
// Don't search moves with negative SEE values
|
|
|
|
if ( !PvNode
|
2013-05-03 19:03:42 +02:00
|
|
|
&& (!InCheck || evasionPrunable)
|
2011-11-12 20:44:06 +01:00
|
|
|
&& move != ttMove
|
2012-09-16 17:16:15 +02:00
|
|
|
&& type_of(move) != PROMOTION
|
2014-05-31 14:23:03 +02:00
|
|
|
&& pos.see_sign(move) < VALUE_ZERO)
|
2011-11-12 20:44:06 +01:00
|
|
|
continue;
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Check for legality just before making the move
|
2013-11-30 20:12:34 +01:00
|
|
|
if (!pos.legal(move, ci.pinned))
|
2012-01-01 01:52:19 +01:00
|
|
|
continue;
|
|
|
|
|
2011-11-12 20:44:06 +01:00
|
|
|
ss->currentMove = move;
|
|
|
|
|
|
|
|
// Make and search the move
|
|
|
|
pos.do_move(move, st, ci, givesCheck);
|
2013-05-03 19:03:42 +02:00
|
|
|
value = givesCheck ? -qsearch<NT, true>(pos, ss+1, -beta, -alpha, depth - ONE_PLY)
|
|
|
|
: -qsearch<NT, false>(pos, ss+1, -beta, -alpha, depth - ONE_PLY);
|
2011-11-12 20:44:06 +01:00
|
|
|
pos.undo_move(move);
|
|
|
|
|
|
|
|
assert(value > -VALUE_INFINITE && value < VALUE_INFINITE);
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
// Check for new best move
|
2011-11-12 20:44:06 +01:00
|
|
|
if (value > bestValue)
|
|
|
|
{
|
|
|
|
bestValue = value;
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
if (value > alpha)
|
|
|
|
{
|
|
|
|
if (PvNode && value < beta) // Update alpha here! Always alpha < beta
|
|
|
|
{
|
|
|
|
alpha = value;
|
|
|
|
bestMove = move;
|
|
|
|
}
|
|
|
|
else // Fail high
|
|
|
|
{
|
|
|
|
TT.store(posKey, value_to_tt(value, ss->ply), BOUND_LOWER,
|
2013-11-30 20:12:34 +01:00
|
|
|
ttDepth, move, ss->staticEval);
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
return value;
|
|
|
|
}
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
// All legal moves have been searched. A special case: If we're in check
|
|
|
|
// and no legal moves were found, it is checkmate.
|
2013-05-03 19:03:42 +02:00
|
|
|
if (InCheck && bestValue == -VALUE_INFINITE)
|
2012-01-01 01:52:19 +01:00
|
|
|
return mated_in(ss->ply); // Plies to mate from the root
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
TT.store(posKey, value_to_tt(bestValue, ss->ply),
|
|
|
|
PvNode && bestValue > oldAlpha ? BOUND_EXACT : BOUND_UPPER,
|
2013-11-30 20:12:34 +01:00
|
|
|
ttDepth, bestMove, ss->staticEval);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
|
|
|
|
|
|
|
|
return bestValue;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
// value_to_tt() adjusts a mate score from "plies to mate from the root" to
|
|
|
|
// "plies to mate from the current position". Non-mate scores are unchanged.
|
2014-05-31 14:23:03 +02:00
|
|
|
// The function is called before storing a value in the transposition table.
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
Value value_to_tt(Value v, int ply) {
|
|
|
|
|
|
|
|
assert(v != VALUE_NONE);
|
|
|
|
|
|
|
|
return v >= VALUE_MATE_IN_MAX_PLY ? v + ply
|
|
|
|
: v <= VALUE_MATED_IN_MAX_PLY ? v - ply : v;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
// value_from_tt() is the inverse of value_to_tt(): It adjusts a mate score
|
2014-05-31 14:23:03 +02:00
|
|
|
// from the transposition table (which refers to the plies to mate/be mated
|
2013-05-03 19:03:42 +02:00
|
|
|
// from current position) to "plies to mate/be mated from the root".
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
Value value_from_tt(Value v, int ply) {
|
|
|
|
|
|
|
|
return v == VALUE_NONE ? VALUE_NONE
|
|
|
|
: v >= VALUE_MATE_IN_MAX_PLY ? v - ply
|
|
|
|
: v <= VALUE_MATED_IN_MAX_PLY ? v + ply : v;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// update_stats() updates killers, history, countermoves and followupmoves stats after a fail-high
|
|
|
|
// of a quiet move.
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt) {
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
if (ss->killers[0] != move)
|
2013-05-03 19:03:42 +02:00
|
|
|
{
|
2014-05-31 14:23:03 +02:00
|
|
|
ss->killers[1] = ss->killers[0];
|
|
|
|
ss->killers[0] = move;
|
2013-05-03 19:03:42 +02:00
|
|
|
}
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Increase history value of the cut-off move and decrease all the other
|
|
|
|
// played quiet moves.
|
|
|
|
Value bonus = Value(int(depth) * int(depth));
|
|
|
|
History.update(pos.moved_piece(move), to_sq(move), bonus);
|
|
|
|
for (int i = 0; i < quietsCnt; ++i)
|
2013-05-03 19:03:42 +02:00
|
|
|
{
|
2014-05-31 14:23:03 +02:00
|
|
|
Move m = quiets[i];
|
|
|
|
History.update(pos.moved_piece(m), to_sq(m), -bonus);
|
2013-05-03 19:03:42 +02:00
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
if (is_ok((ss-1)->currentMove))
|
|
|
|
{
|
|
|
|
Square prevMoveSq = to_sq((ss-1)->currentMove);
|
|
|
|
Countermoves.update(pos.piece_on(prevMoveSq), prevMoveSq, move);
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
if (is_ok((ss-2)->currentMove) && (ss-1)->currentMove == (ss-1)->ttMove)
|
|
|
|
{
|
|
|
|
Square prevOwnMoveSq = to_sq((ss-2)->currentMove);
|
|
|
|
Followupmoves.update(pos.piece_on(prevOwnMoveSq), prevOwnMoveSq, move);
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// When playing with a strength handicap, choose best move among the MultiPV
|
|
|
|
// set using a statistical rule dependent on 'level'. Idea by Heinz van Saanen.
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
Move Skill::pick_move() {
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
static RKISS rk;
|
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// PRNG sequence should be not deterministic
|
2013-11-30 20:12:34 +01:00
|
|
|
for (int i = Time::now() % 50; i > 0; --i)
|
2011-11-12 20:44:06 +01:00
|
|
|
rk.rand<unsigned>();
|
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// RootMoves are already sorted by score in descending order
|
2014-05-31 14:23:03 +02:00
|
|
|
int variance = std::min(RootMoves[0].score - RootMoves[MultiPV - 1].score, PawnValueMg);
|
2013-05-03 19:03:42 +02:00
|
|
|
int weakness = 120 - 2 * level;
|
2012-01-01 01:52:19 +01:00
|
|
|
int max_s = -VALUE_INFINITE;
|
2013-05-03 19:03:42 +02:00
|
|
|
best = MOVE_NONE;
|
2012-01-01 01:52:19 +01:00
|
|
|
|
|
|
|
// Choose best move. For each move score we add two terms both dependent on
|
2014-05-31 14:23:03 +02:00
|
|
|
// weakness. One deterministic and bigger for weaker moves, and one random,
|
2011-11-12 20:44:06 +01:00
|
|
|
// then we choose the move with the resulting highest score.
|
2014-05-31 14:23:03 +02:00
|
|
|
for (size_t i = 0; i < MultiPV; ++i)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-01-01 01:52:19 +01:00
|
|
|
int s = RootMoves[i].score;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
// Don't allow crazy blunders even at very low skills
|
2013-05-03 19:03:42 +02:00
|
|
|
if (i > 0 && RootMoves[i-1].score > s + 2 * PawnValueMg)
|
2011-11-12 20:44:06 +01:00
|
|
|
break;
|
|
|
|
|
2012-01-01 01:52:19 +01:00
|
|
|
// This is our magic formula
|
|
|
|
s += ( weakness * int(RootMoves[0].score - s)
|
|
|
|
+ variance * (rk.rand<unsigned>() % weakness)) / 128;
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
if (s > max_s)
|
|
|
|
{
|
|
|
|
max_s = s;
|
2012-01-01 01:52:19 +01:00
|
|
|
best = RootMoves[i].pv[0];
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
}
|
2012-01-01 01:52:19 +01:00
|
|
|
return best;
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// uci_pv() formats PV information according to the UCI protocol. UCI
|
|
|
|
// requires that all (if any) unsearched PV lines are sent using a previous
|
|
|
|
// search score.
|
2012-09-16 17:16:15 +02:00
|
|
|
|
|
|
|
string uci_pv(const Position& pos, int depth, Value alpha, Value beta) {
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
std::stringstream ss;
|
2013-08-20 20:02:33 +02:00
|
|
|
Time::point elapsed = Time::now() - SearchTime + 1;
|
2013-05-03 19:03:42 +02:00
|
|
|
size_t uciPVSize = std::min((size_t)Options["MultiPV"], RootMoves.size());
|
2012-09-16 17:16:15 +02:00
|
|
|
int selDepth = 0;
|
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
for (size_t i = 0; i < Threads.size(); ++i)
|
2013-05-03 19:03:42 +02:00
|
|
|
if (Threads[i]->maxPly > selDepth)
|
|
|
|
selDepth = Threads[i]->maxPly;
|
2012-09-16 17:16:15 +02:00
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
for (size_t i = 0; i < uciPVSize; ++i)
|
2012-09-16 17:16:15 +02:00
|
|
|
{
|
|
|
|
bool updated = (i <= PVIdx);
|
|
|
|
|
|
|
|
if (depth == 1 && !updated)
|
|
|
|
continue;
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
int d = updated ? depth : depth - 1;
|
|
|
|
Value v = updated ? RootMoves[i].score : RootMoves[i].prevScore;
|
2012-09-16 17:16:15 +02:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
if (ss.rdbuf()->in_avail()) // Not at first line
|
|
|
|
ss << "\n";
|
2012-09-16 17:16:15 +02:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
ss << "info depth " << d
|
|
|
|
<< " seldepth " << selDepth
|
|
|
|
<< " score " << (i == PVIdx ? score_to_uci(v, alpha, beta) : score_to_uci(v))
|
|
|
|
<< " nodes " << pos.nodes_searched()
|
|
|
|
<< " nps " << pos.nodes_searched() * 1000 / elapsed
|
|
|
|
<< " time " << elapsed
|
|
|
|
<< " multipv " << i + 1
|
|
|
|
<< " pv";
|
2012-09-16 17:16:15 +02:00
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
for (size_t j = 0; RootMoves[i].pv[j] != MOVE_NONE; ++j)
|
2014-05-31 14:23:03 +02:00
|
|
|
ss << " " << move_to_uci(RootMoves[i].pv[j], pos.is_chess960());
|
2012-09-16 17:16:15 +02:00
|
|
|
}
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
return ss.str();
|
2012-09-16 17:16:15 +02:00
|
|
|
}
|
|
|
|
|
2012-01-15 02:13:33 +01:00
|
|
|
} // namespace
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
|
2012-01-15 02:13:33 +01:00
|
|
|
/// RootMove::extract_pv_from_tt() builds a PV by adding moves from the TT table.
|
2014-05-31 14:23:03 +02:00
|
|
|
/// We also consider both failing high nodes and BOUND_EXACT nodes here to
|
|
|
|
/// ensure that we have a ponder move even when we fail high at root. This
|
|
|
|
/// results in a long PV to print that is important for position analysis.
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-15 02:13:33 +01:00
|
|
|
void RootMove::extract_pv_from_tt(Position& pos) {
|
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
StateInfo state[MAX_PLY_PLUS_6], *st = state;
|
|
|
|
const TTEntry* tte;
|
2014-05-31 14:23:03 +02:00
|
|
|
int ply = 1; // At root ply is 1...
|
|
|
|
Move m = pv[0]; // ...instead pv[] array starts from 0
|
|
|
|
Value expectedScore = score;
|
2012-01-15 02:13:33 +01:00
|
|
|
|
|
|
|
pv.clear();
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
do {
|
2012-06-04 18:25:51 +02:00
|
|
|
pv.push_back(m);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
assert(MoveList<LEGAL>(pos).contains(pv[ply - 1]));
|
2013-05-03 19:03:42 +02:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
pos.do_move(pv[ply++ - 1], *st++);
|
2013-05-03 19:03:42 +02:00
|
|
|
tte = TT.probe(pos.key());
|
2014-05-31 14:23:03 +02:00
|
|
|
expectedScore = -expectedScore;
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
} while ( tte
|
2014-05-31 14:23:03 +02:00
|
|
|
&& expectedScore == value_from_tt(tte->value(), ply)
|
2013-11-30 20:12:34 +01:00
|
|
|
&& pos.pseudo_legal(m = tte->move()) // Local copy, TT could change
|
|
|
|
&& pos.legal(m, pos.pinned_pieces(pos.side_to_move()))
|
2013-05-03 19:03:42 +02:00
|
|
|
&& ply < MAX_PLY
|
2014-05-31 14:23:03 +02:00
|
|
|
&& (!pos.is_draw() || ply <= 2));
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
pv.push_back(MOVE_NONE); // Must be zero-terminating
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
while (--ply) pos.undo_move(pv[ply - 1]);
|
2012-01-15 02:13:33 +01:00
|
|
|
}
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-15 02:13:33 +01:00
|
|
|
/// RootMove::insert_pv_in_tt() is called at the end of a search iteration, and
|
|
|
|
/// inserts the PV back into the TT. This makes sure the old PV moves are searched
|
|
|
|
/// first, even if the old TT entries have been overwritten.
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-15 02:13:33 +01:00
|
|
|
void RootMove::insert_pv_in_tt(Position& pos) {
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
StateInfo state[MAX_PLY_PLUS_6], *st = state;
|
|
|
|
const TTEntry* tte;
|
2014-05-31 14:23:03 +02:00
|
|
|
int idx = 0; // Ply starts from 1, we need to start from 0
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-01-15 02:13:33 +01:00
|
|
|
do {
|
2013-05-03 19:03:42 +02:00
|
|
|
tte = TT.probe(pos.key());
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
if (!tte || tte->move() != pv[idx]) // Don't overwrite correct entries
|
|
|
|
TT.store(pos.key(), VALUE_NONE, BOUND_NONE, DEPTH_NONE, pv[idx], VALUE_NONE);
|
2013-05-03 19:03:42 +02:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
assert(MoveList<LEGAL>(pos).contains(pv[idx]));
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
pos.do_move(pv[idx++], *st++);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
} while (pv[idx] != MOVE_NONE);
|
2013-05-03 19:03:42 +02:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
while (idx) pos.undo_move(pv[--idx]);
|
2012-01-15 02:13:33 +01:00
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
/// Thread::idle_loop() is where the thread is parked when it has no work to do
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
void Thread::idle_loop() {
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
// Pointer 'this_sp' is not null only if we are called from split(), and not
|
2014-05-31 14:23:03 +02:00
|
|
|
// at the thread creation. This means we are the split point's master.
|
2013-05-03 19:03:42 +02:00
|
|
|
SplitPoint* this_sp = splitPointsSize ? activeSplitPoint : NULL;
|
2012-09-16 17:16:15 +02:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(!this_sp || (this_sp->masterThread == this && searching));
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
while (true)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
// If we are not searching, wait for a condition to be signaled instead of
|
|
|
|
// wasting CPU time polling for work.
|
2014-05-31 14:23:03 +02:00
|
|
|
while (!searching || exit)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
if (exit)
|
2012-01-01 01:52:19 +01:00
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(!this_sp);
|
2012-01-01 01:52:19 +01:00
|
|
|
return;
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
// Grab the lock to avoid races with Thread::notify_one()
|
2012-09-16 17:16:15 +02:00
|
|
|
mutex.lock();
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
// If we are master and all slaves have finished then exit idle_loop
|
2014-05-31 14:23:03 +02:00
|
|
|
if (this_sp && this_sp->slavesMask.none())
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2012-09-16 17:16:15 +02:00
|
|
|
mutex.unlock();
|
2011-11-12 20:44:06 +01:00
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Do sleep after retesting sleep conditions under lock protection. In
|
2012-01-01 01:52:19 +01:00
|
|
|
// particular we need to avoid a deadlock in case a master thread has,
|
2013-05-03 19:03:42 +02:00
|
|
|
// in the meanwhile, allocated us and sent the notify_one() call before
|
|
|
|
// we had the chance to grab the lock.
|
|
|
|
if (!searching && !exit)
|
2012-09-16 17:16:15 +02:00
|
|
|
sleepCondition.wait(mutex);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
mutex.unlock();
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
|
|
|
|
// If this thread has been assigned work, launch a search
|
2013-05-03 19:03:42 +02:00
|
|
|
if (searching)
|
2011-11-12 20:44:06 +01:00
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(!exit);
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
Threads.mutex.lock();
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(searching);
|
2013-08-20 20:02:33 +02:00
|
|
|
assert(activeSplitPoint);
|
2013-05-03 19:03:42 +02:00
|
|
|
SplitPoint* sp = activeSplitPoint;
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
Threads.mutex.unlock();
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
Stack stack[MAX_PLY_PLUS_6], *ss = stack+2; // To allow referencing (ss-2)
|
2012-06-04 18:25:51 +02:00
|
|
|
Position pos(*sp->pos, this);
|
|
|
|
|
2013-08-20 20:02:33 +02:00
|
|
|
std::memcpy(ss-2, sp->ss-2, 5 * sizeof(Stack));
|
|
|
|
ss->splitPoint = sp;
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
sp->mutex.lock();
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(activePosition == NULL);
|
|
|
|
|
|
|
|
activePosition = &pos;
|
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
if (sp->nodeType == NonPV)
|
|
|
|
search<NonPV, true>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
|
|
|
|
|
|
|
|
else if (sp->nodeType == PV)
|
|
|
|
search<PV, true>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
|
|
|
|
|
|
|
|
else if (sp->nodeType == Root)
|
|
|
|
search<Root, true>(pos, ss, sp->alpha, sp->beta, sp->depth, sp->cutNode);
|
|
|
|
|
|
|
|
else
|
2012-01-01 01:52:19 +01:00
|
|
|
assert(false);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(searching);
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
searching = false;
|
|
|
|
activePosition = NULL;
|
2014-05-31 14:23:03 +02:00
|
|
|
sp->slavesMask.reset(idx);
|
|
|
|
sp->allSlavesSearching = false;
|
2012-06-04 18:25:51 +02:00
|
|
|
sp->nodes += pos.nodes_searched();
|
2011-11-12 20:44:06 +01:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// Wake up the master thread so to allow it to return from the idle
|
|
|
|
// loop in case we are the last slave of the split point.
|
|
|
|
if ( this != sp->masterThread
|
|
|
|
&& sp->slavesMask.none())
|
2012-09-16 17:16:15 +02:00
|
|
|
{
|
2013-05-03 19:03:42 +02:00
|
|
|
assert(!sp->masterThread->searching);
|
|
|
|
sp->masterThread->notify_one();
|
2012-09-16 17:16:15 +02:00
|
|
|
}
|
2012-06-04 18:25:51 +02:00
|
|
|
|
2014-05-31 14:23:03 +02:00
|
|
|
// After releasing the lock we can't access any SplitPoint related data
|
|
|
|
// in a safe way because it could have been released under our feet by
|
|
|
|
// the sp master.
|
2012-09-16 17:16:15 +02:00
|
|
|
sp->mutex.unlock();
|
2014-05-31 14:23:03 +02:00
|
|
|
|
|
|
|
// Try to late join to another split point if none of its slaves has
|
|
|
|
// already finished.
|
|
|
|
if (Threads.size() > 2)
|
|
|
|
for (size_t i = 0; i < Threads.size(); ++i)
|
|
|
|
{
|
|
|
|
int size = Threads[i]->splitPointsSize; // Local copy
|
|
|
|
sp = size ? &Threads[i]->splitPoints[size - 1] : NULL;
|
|
|
|
|
|
|
|
if ( sp
|
|
|
|
&& sp->allSlavesSearching
|
|
|
|
&& available_to(Threads[i]))
|
|
|
|
{
|
|
|
|
// Recheck the conditions under lock protection
|
|
|
|
Threads.mutex.lock();
|
|
|
|
sp->mutex.lock();
|
|
|
|
|
|
|
|
if ( sp->allSlavesSearching
|
|
|
|
&& available_to(Threads[i]))
|
|
|
|
{
|
|
|
|
sp->slavesMask.set(idx);
|
|
|
|
activeSplitPoint = sp;
|
|
|
|
searching = true;
|
|
|
|
}
|
|
|
|
|
|
|
|
sp->mutex.unlock();
|
|
|
|
Threads.mutex.unlock();
|
|
|
|
|
|
|
|
break; // Just a single attempt
|
|
|
|
}
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
// If this thread is the master of a split point and all slaves have finished
|
|
|
|
// their work at this split point, return from the idle loop.
|
2014-05-31 14:23:03 +02:00
|
|
|
if (this_sp && this_sp->slavesMask.none())
|
2013-05-03 19:03:42 +02:00
|
|
|
{
|
|
|
|
this_sp->mutex.lock();
|
2014-05-31 14:23:03 +02:00
|
|
|
bool finished = this_sp->slavesMask.none(); // Retest under lock protection
|
2013-05-03 19:03:42 +02:00
|
|
|
this_sp->mutex.unlock();
|
|
|
|
if (finished)
|
|
|
|
return;
|
|
|
|
}
|
2011-11-12 20:44:06 +01:00
|
|
|
}
|
|
|
|
}
|
2012-01-01 01:52:19 +01:00
|
|
|
|
|
|
|
|
2012-01-07 03:07:28 +01:00
|
|
|
/// check_time() is called by the timer thread when the timer triggers. It is
|
2014-05-31 14:23:03 +02:00
|
|
|
/// used to print debug info and, more importantly, to detect when we are out of
|
|
|
|
/// available time and thus stop the search.
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2012-01-07 03:07:28 +01:00
|
|
|
void check_time() {
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
static Time::point lastInfoTime = Time::now();
|
2013-05-03 19:03:42 +02:00
|
|
|
int64_t nodes = 0; // Workaround silly 'uninitialized' gcc warning
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
if (Time::now() - lastInfoTime >= 1000)
|
2012-01-01 01:52:19 +01:00
|
|
|
{
|
2012-09-16 17:16:15 +02:00
|
|
|
lastInfoTime = Time::now();
|
2012-01-01 01:52:19 +01:00
|
|
|
dbg_print();
|
|
|
|
}
|
|
|
|
|
|
|
|
if (Limits.ponder)
|
|
|
|
return;
|
|
|
|
|
2013-05-03 19:03:42 +02:00
|
|
|
if (Limits.nodes)
|
|
|
|
{
|
|
|
|
Threads.mutex.lock();
|
|
|
|
|
|
|
|
nodes = RootPos.nodes_searched();
|
|
|
|
|
|
|
|
// Loop across all split points and sum accumulated SplitPoint nodes plus
|
|
|
|
// all the currently active positions nodes.
|
2013-11-30 20:12:34 +01:00
|
|
|
for (size_t i = 0; i < Threads.size(); ++i)
|
|
|
|
for (int j = 0; j < Threads[i]->splitPointsSize; ++j)
|
2013-05-03 19:03:42 +02:00
|
|
|
{
|
|
|
|
SplitPoint& sp = Threads[i]->splitPoints[j];
|
|
|
|
|
|
|
|
sp.mutex.lock();
|
|
|
|
|
|
|
|
nodes += sp.nodes;
|
2014-05-31 14:23:03 +02:00
|
|
|
|
|
|
|
for (size_t idx = 0; idx < Threads.size(); ++idx)
|
|
|
|
if (sp.slavesMask.test(idx) && Threads[idx]->activePosition)
|
|
|
|
nodes += Threads[idx]->activePosition->nodes_searched();
|
2013-05-03 19:03:42 +02:00
|
|
|
|
|
|
|
sp.mutex.unlock();
|
|
|
|
}
|
|
|
|
|
|
|
|
Threads.mutex.unlock();
|
|
|
|
}
|
|
|
|
|
2012-09-16 17:16:15 +02:00
|
|
|
Time::point elapsed = Time::now() - SearchTime;
|
2012-01-01 01:52:19 +01:00
|
|
|
bool stillAtFirstMove = Signals.firstRootMove
|
|
|
|
&& !Signals.failedLowAtRoot
|
2014-05-31 14:23:03 +02:00
|
|
|
&& elapsed > TimeMgr.available_time() * 75 / 100;
|
2012-01-01 01:52:19 +01:00
|
|
|
|
2013-11-30 20:12:34 +01:00
|
|
|
bool noMoreTime = elapsed > TimeMgr.maximum_time() - 2 * TimerThread::Resolution
|
2012-01-01 01:52:19 +01:00
|
|
|
|| stillAtFirstMove;
|
|
|
|
|
2012-01-07 03:07:28 +01:00
|
|
|
if ( (Limits.use_time_management() && noMoreTime)
|
2013-05-03 19:03:42 +02:00
|
|
|
|| (Limits.movetime && elapsed >= Limits.movetime)
|
|
|
|
|| (Limits.nodes && nodes >= Limits.nodes))
|
2012-01-01 01:52:19 +01:00
|
|
|
Signals.stop = true;
|
|
|
|
}
|