2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
4 Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
5 Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
7 Stockfish is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
12 Stockfish is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>.
27 TimeManagement Time; // Our global time management object
31 enum TimeType { OptimumTime, MaxTime };
33 int remaining(int myTime, int myInc, int moveOverhead, int movesToGo,
34 int ply, bool ponder, TimeType type) {
39 int moveNumber = (ply + 1) / 2;
40 double ratio; // Which ratio of myTime we are going to use. It's <= 1 if not ponder
43 // Usage of increment follows quadratic distribution with the maximum at move 25
44 double inc = myInc * std::max(55.0, 120.0 - 0.12 * (moveNumber - 25) * (moveNumber - 25));
46 // In moves-to-go we distribute time according to a quadratic function with
47 // the maximum around move 20 for 40 moves in y time case.
50 ratio = (type == OptimumTime ? 1.0 : 6.0) / std::min(50, movesToGo);
53 ratio *= 1.1 - 0.001 * (moveNumber - 20) * (moveNumber - 20);
57 // Otherwise we increase usage of remaining time as the game goes on
60 sd = 1 + 20 * moveNumber / (500.0 + moveNumber);
61 ratio = (type == OptimumTime ? 0.017 : 0.07) * sd;
64 ratio = std::min(1.0, ratio * (1 + inc / (myTime * sd)));
68 if (ponder && type == OptimumTime)
71 int time = int(ratio * (myTime - moveOverhead));
73 if (type == OptimumTime)
74 time -= 10; // Keep always at least 10 millisecs on the clock
76 return std::max(0, time);
82 /// init() is called at the beginning of the search and calculates the allowed
83 /// thinking time out of the time control and current game ply. We support four
84 /// different kinds of time controls, passed in 'limits':
86 /// inc == 0 && movestogo == 0 means: x basetime [sudden death!]
87 /// inc == 0 && movestogo != 0 means: x moves in y minutes
88 /// inc > 0 && movestogo == 0 means: x basetime + z increment
89 /// inc > 0 && movestogo != 0 means: x moves in y minutes + z increment
91 void TimeManagement::init(Search::LimitsType& limits, Color us, int ply)
93 int moveOverhead = Options["Move Overhead"];
94 int npmsec = Options["nodestime"];
95 bool ponder = Options["Ponder"];
97 // If we have to play in 'nodes as time' mode, then convert from time
98 // to nodes, and use resulting values in time management formulas.
99 // WARNING: Given npms (nodes per millisecond) must be much lower then
100 // the real engine speed to avoid time losses.
103 if (!availableNodes) // Only once at game start
104 availableNodes = npmsec * limits.time[us]; // Time is in msec
106 // Convert from millisecs to nodes
107 limits.time[us] = (int)availableNodes;
108 limits.inc[us] *= npmsec;
109 limits.npmsec = npmsec;
112 startTime = limits.startTime;
113 optimumTime = remaining(limits.time[us], limits.inc[us], moveOverhead,
114 limits.movestogo, ply, ponder, OptimumTime);
115 maximumTime = remaining(limits.time[us], limits.inc[us], moveOverhead,
116 limits.movestogo, ply, ponder, MaxTime);