/*
Stockfish, a UCI chess playing engine derived from Glaurung 2.1
- Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
- Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
- Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+ Copyright (C) 2004-2023 The Stockfish developers (see AUTHORS file)
Stockfish is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include "timeman.h"
+
#include <algorithm>
+#include <cmath>
#include "search.h"
-#include "timeman.h"
#include "uci.h"
-TimeManagement Time; // Our global time management object
+namespace Stockfish {
-namespace {
+TimeManagement Time; // Our global time management object
- enum TimeType { OptimumTime, MaxTime };
- int remaining(int myTime, int myInc, int moveOverhead, int movesToGo,
- int ply, bool ponder, TimeType type) {
+// Called at the beginning of the search and calculates
+// the bounds of time allowed for the current game ply. We currently support:
+// 1) x basetime (+ z increment)
+// 2) x moves in y seconds (+ z increment)
+void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
- if (myTime <= 0)
- return 0;
+ // If we have no time, no need to initialize TM, except for the start time,
+ // which is used by movetime.
+ startTime = limits.startTime;
+ if (limits.time[us] == 0)
+ return;
- int moveNumber = (ply + 1) / 2;
- double ratio; // Which ratio of myTime we are going to use. It's <= 1 if not ponder
- double sd = 8.5;
+ TimePoint moveOverhead = TimePoint(Options["Move Overhead"]);
+ TimePoint npmsec = TimePoint(Options["nodestime"]);
- // Usage of increment follows quadratic distribution with the maximum at move 25
- double inc = myInc * std::max(55.0, 120.0 - 0.12 * (moveNumber - 25) * (moveNumber - 25));
+ // optScale is a percentage of available time to use for the current move.
+ // maxScale is a multiplier applied to optimumTime.
+ double optScale, maxScale;
- // In moves-to-go we distribute time according to a quadratic function with
- // the maximum around move 20 for 40 moves in y time case.
- if (movesToGo)
+ // If we have to play in 'nodes as time' mode, then convert from time
+ // to nodes, and use resulting values in time management formulas.
+ // WARNING: to avoid time losses, the given npmsec (nodes per millisecond)
+ // must be much lower than the real engine speed.
+ if (npmsec)
{
- ratio = (type == OptimumTime ? 1.0 : 6.0) / std::min(50, movesToGo);
+ if (!availableNodes) // Only once at game start
+ availableNodes = npmsec * limits.time[us]; // Time is in msec
- if (moveNumber <= 40)
- ratio *= 1.1 - 0.001 * (moveNumber - 20) * (moveNumber - 20);
- else
- ratio *= 1.5;
+ // Convert from milliseconds to nodes
+ limits.time[us] = TimePoint(availableNodes);
+ limits.inc[us] *= npmsec;
+ limits.npmsec = npmsec;
}
- // Otherwise we increase usage of remaining time as the game goes on
- else
- {
- sd = 1 + 20 * moveNumber / (500.0 + moveNumber);
- ratio = (type == OptimumTime ? 0.017 : 0.07) * sd;
- }
-
- ratio = std::min(1.0, ratio * (1 + inc / (myTime * sd)));
-
- assert(ratio <= 1);
-
- if (ponder && type == OptimumTime)
- ratio *= 1.25;
- int time = int(ratio * (myTime - moveOverhead));
+ // Maximum move horizon of 50 moves
+ int mtg = limits.movestogo ? std::min(limits.movestogo, 50) : 50;
- if (type == OptimumTime)
- time -= 10; // Keep always at least 10 millisecs on the clock
+ // Make sure timeLeft is > 0 since we may use it as a divisor
+ TimePoint timeLeft = std::max(TimePoint(1), limits.time[us] + limits.inc[us] * (mtg - 1)
+ - moveOverhead * (2 + mtg));
- return std::max(0, time);
- }
+ // Use extra time with larger increments
+ double optExtra = std::clamp(1.0 + 12.5 * limits.inc[us] / limits.time[us], 1.0, 1.11);
-} // namespace
+ // Calculate time constants based on current time left.
+ double optConstant = std::min(0.00334 + 0.0003 * std::log10(limits.time[us] / 1000.0), 0.0049);
+ double maxConstant = std::max(3.4 + 3.0 * std::log10(limits.time[us] / 1000.0), 2.76);
+ // x basetime (+ z increment)
+ // If there is a healthy increment, timeLeft can exceed actual available
+ // game time for the current move, so also cap to 20% of available game time.
+ if (limits.movestogo == 0)
+ {
+ optScale = std::min(0.0120 + std::pow(ply + 3.1, 0.44) * optConstant,
+ 0.21 * limits.time[us] / double(timeLeft))
+ * optExtra;
+ maxScale = std::min(6.9, maxConstant + ply / 12.2);
+ }
-/// init() is called at the beginning of the search and calculates the allowed
-/// thinking time out of the time control and current game ply. We support four
-/// different kinds of time controls, passed in 'limits':
-///
-/// inc == 0 && movestogo == 0 means: x basetime [sudden death!]
-/// inc == 0 && movestogo != 0 means: x moves in y minutes
-/// inc > 0 && movestogo == 0 means: x basetime + z increment
-/// inc > 0 && movestogo != 0 means: x moves in y minutes + z increment
-
-void TimeManagement::init(Search::LimitsType& limits, Color us, int ply)
-{
- int moveOverhead = Options["Move Overhead"];
- int npmsec = Options["nodestime"];
- bool ponder = Options["Ponder"];
-
- // If we have to play in 'nodes as time' mode, then convert from time
- // to nodes, and use resulting values in time management formulas.
- // WARNING: Given npms (nodes per millisecond) must be much lower then
- // the real engine speed to avoid time losses.
- if (npmsec)
- {
- if (!availableNodes) // Only once at game start
- availableNodes = npmsec * limits.time[us]; // Time is in msec
+ // x moves in y seconds (+ z increment)
+ else
+ {
+ optScale = std::min((0.88 + ply / 116.4) / mtg, 0.88 * limits.time[us] / double(timeLeft));
+ maxScale = std::min(6.3, 1.5 + 0.11 * mtg);
+ }
- // Convert from millisecs to nodes
- limits.time[us] = (int)availableNodes;
- limits.inc[us] *= npmsec;
- limits.npmsec = npmsec;
- }
+ // Limit the maximum possible time for this move
+ optimumTime = TimePoint(optScale * timeLeft);
+ maximumTime =
+ TimePoint(std::min(0.84 * limits.time[us] - moveOverhead, maxScale * optimumTime)) - 10;
- startTime = limits.startTime;
- optimumTime = remaining(limits.time[us], limits.inc[us], moveOverhead,
- limits.movestogo, ply, ponder, OptimumTime);
- maximumTime = remaining(limits.time[us], limits.inc[us], moveOverhead,
- limits.movestogo, ply, ponder, MaxTime);
+ if (Options["Ponder"])
+ optimumTime += optimumTime / 4;
}
+
+} // namespace Stockfish
projects / stockfish / blobdiff