Convert project to Android Studio.

DroidFishApp/src/main/cpp/stockfish/timeman.cpp

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+/*
+  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) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <algorithm>
+#include <cfloat>
+#include <cmath>
+
+#include "search.h"
+#include "timeman.h"
+#include "uci.h"
+
+TimeManagement Time; // Our global time management object
+
+namespace {
+
+  enum TimeType { OptimumTime, MaxTime };
+
+  constexpr int MoveHorizon   = 50;   // Plan time management at most this many moves ahead
+  constexpr double MaxRatio   = 7.3;  // When in trouble, we can step over reserved time with this ratio
+  constexpr double StealRatio = 0.34; // However we must not steal time from remaining moves over this ratio
+
+
+  // move_importance() is a skew-logistic function based on naive statistical
+  // analysis of "how many games are still undecided after n half-moves". Game
+  // is considered "undecided" as long as neither side has >275cp advantage.
+  // Data was extracted from the CCRL game database with some simple filtering criteria.
+
+  double move_importance(int ply) {
+
+    constexpr double XScale = 6.85;
+    constexpr double XShift = 64.5;
+    constexpr double Skew   = 0.171;
+
+    return pow((1 + exp((ply - XShift) / XScale)), -Skew) + DBL_MIN; // Ensure non-zero
+  }
+
+  template<TimeType T>
+  TimePoint remaining(TimePoint myTime, int movesToGo, int ply, TimePoint slowMover) {
+
+    constexpr double TMaxRatio   = (T == OptimumTime ? 1.0 : MaxRatio);
+    constexpr double TStealRatio = (T == OptimumTime ? 0.0 : StealRatio);
+
+    double moveImportance = (move_importance(ply) * slowMover) / 100.0;
+    double otherMovesImportance = 0.0;
+
+    for (int i = 1; i < movesToGo; ++i)
+        otherMovesImportance += move_importance(ply + 2 * i);
+
+    double ratio1 = (TMaxRatio * moveImportance) / (TMaxRatio * moveImportance + otherMovesImportance);
+    double ratio2 = (moveImportance + TStealRatio * otherMovesImportance) / (moveImportance + otherMovesImportance);
+
+    return TimePoint(myTime * std::min(ratio1, ratio2)); // Intel C++ asks for an explicit cast
+  }
+
+} // namespace
+
+
+/// 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) {
+
+  TimePoint minThinkingTime = Options["Minimum Thinking Time"];
+  TimePoint moveOverhead    = Options["Move Overhead"];
+  TimePoint slowMover       = Options["Slow Mover"];
+  TimePoint npmsec          = Options["nodestime"];
+  TimePoint hypMyTime;
+
+  // 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)
+  {
+      if (!availableNodes) // Only once at game start
+          availableNodes = npmsec * limits.time[us]; // Time is in msec
+
+      // Convert from milliseconds to nodes
+      limits.time[us] = TimePoint(availableNodes);
+      limits.inc[us] *= npmsec;
+      limits.npmsec = npmsec;
+  }
+
+  startTime = limits.startTime;
+  optimumTime = maximumTime = std::max(limits.time[us], minThinkingTime);
+
+  const int maxMTG = limits.movestogo ? std::min(limits.movestogo, MoveHorizon) : MoveHorizon;
+
+  // We calculate optimum time usage for different hypothetical "moves to go" values
+  // and choose the minimum of calculated search time values. Usually the greatest
+  // hypMTG gives the minimum values.
+  for (int hypMTG = 1; hypMTG <= maxMTG; ++hypMTG)
+  {
+      // Calculate thinking time for hypothetical "moves to go"-value
+      hypMyTime =  limits.time[us]
+                 + limits.inc[us] * (hypMTG - 1)
+                 - moveOverhead * (2 + std::min(hypMTG, 40));
+
+      hypMyTime = std::max(hypMyTime, TimePoint(0));
+
+      TimePoint t1 = minThinkingTime + remaining<OptimumTime>(hypMyTime, hypMTG, ply, slowMover);
+      TimePoint t2 = minThinkingTime + remaining<MaxTime    >(hypMyTime, hypMTG, ply, slowMover);
+
+      optimumTime = std::min(t1, optimumTime);
+      maximumTime = std::min(t2, maximumTime);
+  }
+
+  if (Options["Ponder"])
+      optimumTime += optimumTime / 4;
+}