Mark all compile-time constants as constexpr.

[stockfish] / src / timeman.cpp

diff --git a/src/timeman.cpp b/src/timeman.cpp
index e9f1ffe5389597fa52e58fc9fdf604c49ee0af85..e63454ebd7b3f85f4d6dedaafbe4df949e7133d2 100644 (file)
--- a/src/timeman.cpp
+++ b/src/timeman.cpp
@@ -2,7 +2,7 @@
   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) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2018 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
@@ -32,30 +32,32 @@ namespace {
 
   enum TimeType { OptimumTime, MaxTime };
 
-  const int MoveHorizon   = 50;   // Plan time management at most this many moves ahead
-  const double MaxRatio   = 7.09;  // When in trouble, we can step over reserved time with this ratio
-  const double StealRatio = 0.35; // However we must not steal time from remaining moves over this ratio
+  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 an exponential function based on naive observation
-  // that a game is closer to be decided after each half-move. This function
-  // should be decreasing and with "nice" convexity properties.
+  // 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) {
 
-    const double PlyScale = 109.3265;
-    const double PlyGrowth = 4.0;
+    constexpr double XScale = 6.85;
+    constexpr double XShift = 64.5;
+    constexpr double Skew   = 0.171;
 
-    return exp(-pow(ply / PlyScale, PlyGrowth)) + DBL_MIN; // Ensure non-zero
+    return pow((1 + exp((ply - XShift) / XScale)), -Skew) + DBL_MIN; // Ensure non-zero
   }
 
   template<TimeType T>
-  int remaining(int myTime, int movesToGo, int ply)
-  {
-    const double TMaxRatio   = (T == OptimumTime ? 1 : MaxRatio);
-    const double TStealRatio = (T == OptimumTime ? 0 : StealRatio);
+  int remaining(int myTime, int movesToGo, int ply, int slowMover) {
+
+    constexpr double TMaxRatio   = (T == OptimumTime ? 1 : MaxRatio);
+    constexpr double TStealRatio = (T == OptimumTime ? 0 : StealRatio);
 
-    double moveImportance = move_importance(ply);
+    double moveImportance = (move_importance(ply) * slowMover) / 100;
     double otherMovesImportance = 0;
 
     for (int i = 1; i < movesToGo; ++i)
@@ -79,10 +81,11 @@ namespace {
 ///  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)
-{
+void TimeManagement::init(Search::LimitsType& limits, Color us, int ply) {
+
   int minThinkingTime = Options["Minimum Thinking Time"];
   int moveOverhead    = Options["Move Overhead"];
+  int slowMover       = Options["Slow Mover"];
   int npmsec          = Options["nodestime"];
 
   // If we have to play in 'nodes as time' mode, then convert from time
@@ -103,12 +106,12 @@ void TimeManagement::init(Search::LimitsType& limits, Color us, int ply)
   startTime = limits.startTime;
   optimumTime = maximumTime = std::max(limits.time[us], minThinkingTime);
 
-  const int MaxMTG = limits.movestogo ? std::min(limits.movestogo, MoveHorizon) : MoveHorizon;
+  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)
+  for (int hypMTG = 1; hypMTG <= maxMTG; ++hypMTG)
   {
       // Calculate thinking time for hypothetical "moves to go"-value
       int hypMyTime =  limits.time[us]
@@ -117,8 +120,8 @@ void TimeManagement::init(Search::LimitsType& limits, Color us, int ply)
 
       hypMyTime = std::max(hypMyTime, 0);
 
-      int t1 = minThinkingTime + remaining<OptimumTime>(hypMyTime, hypMTG, ply);
-      int t2 = minThinkingTime + remaining<MaxTime    >(hypMyTime, hypMTG, ply);
+      int t1 = minThinkingTime + remaining<OptimumTime>(hypMyTime, hypMTG, ply, slowMover);
+      int t2 = minThinkingTime + remaining<MaxTime    >(hypMyTime, hypMTG, ply, slowMover);
 
       optimumTime = std::min(t1, optimumTime);
       maximumTime = std::min(t2, maximumTime);