2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad
6 Stockfish is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 Stockfish is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
26 #include "ucioption.h"
32 const int MoveHorizon = 50; // Plan time management at most this many moves ahead
33 const double MaxRatio = 7.0; // When in trouble, we can step over reserved time with this ratio
34 const double StealRatio = 0.33; // However we must not steal time from remaining moves over this ratio
36 const double xscale = 9.3;
37 const double xshift = 59.8;
38 const double skewfactor = 0.172;
41 /// move_importance() is a skew-logistic function based on naive statistical
42 /// analysis of "how many games are still undecided after n half-moves". Game
43 /// is considered "undecided" as long as neither side has >275cp advantage.
44 /// Data was extracted from CCRL game database with some simple filtering criteria.
46 double move_importance(int ply) {
48 return pow((1 + exp((ply - xshift) / xscale)), -skewfactor) + DBL_MIN; // Ensure non-zero
52 /// Function Prototypes
54 enum TimeType { OptimumTime, MaxTime };
57 int remaining(int myTime, int movesToGo, int fullMoveNumber, int slowMover);
61 void TimeManager::pv_instability(double bestMoveChanges) {
63 unstablePVExtraTime = int(bestMoveChanges * optimumSearchTime / 1.4);
67 void TimeManager::init(const Search::LimitsType& limits, int currentPly, Color us)
69 /* We support four different kinds of time controls:
71 increment == 0 && movesToGo == 0 means: x basetime [sudden death!]
72 increment == 0 && movesToGo != 0 means: x moves in y minutes
73 increment > 0 && movesToGo == 0 means: x basetime + z increment
74 increment > 0 && movesToGo != 0 means: x moves in y minutes + z increment
76 Time management is adjusted by following UCI parameters:
78 emergencyMoveHorizon: Be prepared to always play at least this many moves
79 emergencyBaseTime : Always attempt to keep at least this much time (in ms) at clock
80 emergencyMoveTime : Plus attempt to keep at least this much time for each remaining emergency move
81 minThinkingTime : No matter what, use at least this much thinking before doing the move
84 int hypMTG, hypMyTime, t1, t2;
86 // Read uci parameters
87 int emergencyMoveHorizon = Options["Emergency Move Horizon"];
88 int emergencyBaseTime = Options["Emergency Base Time"];
89 int emergencyMoveTime = Options["Emergency Move Time"];
90 int minThinkingTime = Options["Minimum Thinking Time"];
91 int slowMover = Options["Slow Mover"];
93 // Initialize all to maximum values but unstablePVExtraTime that is reset
94 unstablePVExtraTime = 0;
95 optimumSearchTime = maximumSearchTime = std::max(limits.time[us], minThinkingTime);
97 // We calculate optimum time usage for different hypothetical "moves to go"-values and choose the
98 // minimum of calculated search time values. Usually the greatest hypMTG gives the minimum values.
99 for (hypMTG = 1; hypMTG <= (limits.movestogo ? std::min(limits.movestogo, MoveHorizon) : MoveHorizon); ++hypMTG)
101 // Calculate thinking time for hypothetical "moves to go"-value
102 hypMyTime = limits.time[us]
103 + limits.inc[us] * (hypMTG - 1)
105 - emergencyMoveTime * std::min(hypMTG, emergencyMoveHorizon);
107 hypMyTime = std::max(hypMyTime, 0);
109 t1 = minThinkingTime + remaining<OptimumTime>(hypMyTime, hypMTG, currentPly, slowMover);
110 t2 = minThinkingTime + remaining<MaxTime>(hypMyTime, hypMTG, currentPly, slowMover);
112 optimumSearchTime = std::min(optimumSearchTime, t1);
113 maximumSearchTime = std::min(maximumSearchTime, t2);
116 if (Options["Ponder"])
117 optimumSearchTime += optimumSearchTime / 4;
119 // Make sure that maxSearchTime is not over absoluteMaxSearchTime
120 optimumSearchTime = std::min(optimumSearchTime, maximumSearchTime);
127 int remaining(int myTime, int movesToGo, int currentPly, int slowMover)
129 const double TMaxRatio = (T == OptimumTime ? 1 : MaxRatio);
130 const double TStealRatio = (T == OptimumTime ? 0 : StealRatio);
132 double thisMoveImportance = (move_importance(currentPly) * slowMover) / 100;
133 double otherMovesImportance = 0;
135 for (int i = 1; i < movesToGo; ++i)
136 otherMovesImportance += move_importance(currentPly + 2 * i);
138 double ratio1 = (TMaxRatio * thisMoveImportance) / (TMaxRatio * thisMoveImportance + otherMovesImportance);
139 double ratio2 = (thisMoveImportance + TStealRatio * otherMovesImportance) / (thisMoveImportance + otherMovesImportance);
141 return int(floor(myTime * std::min(ratio1, ratio2)));