Skip quiet moves based on moveCount pruning threshold and history stats

[stockfish] / src / movepick.h

diff --git a/src/movepick.h b/src/movepick.h
index b59b0e93ba33a469419a9dbbfab8ecbad3eb6c6b..c19141820e3397804580a06fbc8b02df12e5e7a0 100644 (file)
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -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) 2015-2017 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
@@ -29,37 +29,9 @@
 #include "types.h"
 
 
-/// The Stats struct stores moves statistics. According to the template parameter
-/// the class can store History and Countermoves. History records how often
-/// different moves have been successful or unsuccessful during the current search
-/// and is used for reduction and move ordering decisions.
-/// Countermoves store the move that refute a previous one. Entries are stored
-/// using only the moving piece and destination square, hence two moves with
-/// different origin but same destination and piece will be considered identical.
-template<typename T, bool CM = false>
-struct Stats {
-  const T* operator[](Piece pc) const { return table[pc]; }
-  T* operator[](Piece pc) { return table[pc]; }
-  void clear() { std::memset(table, 0, sizeof(table)); }
-  void update(Piece pc, Square to, Move m) { table[pc][to] = m; }
-  void update(Piece pc, Square to, Value v) {
-
-    if (abs(int(v)) >= 324)
-        return;
-
-    table[pc][to] -= table[pc][to] * abs(int(v)) / (CM ? 936 : 324);
-    table[pc][to] += int(v) * 32;
-  }
-
-private:
-  T table[PIECE_NB][SQUARE_NB];
-};
-
-typedef Stats<Move> MoveStats;
-typedef Stats<Value, true> CounterMoveStats;
-typedef Stats<CounterMoveStats> CounterMoveHistoryStats;
-
-struct FromToStats {
+/// HistoryStats records how often quiet moves have been successful or unsuccessful
+/// during the current search, and is used for reduction and move ordering decisions.
+struct HistoryStats {
 
   static const Value Max = Value(1 << 28);
 
@@ -67,9 +39,6 @@ struct FromToStats {
   void clear() { std::memset(table, 0, sizeof(table)); }
   void update(Color c, Move m, Value v) {
 
-    if (abs(int(v)) >= 324)
-        return;
-
     Square from = from_sq(m);
     Square to = to_sq(m);
 
@@ -82,6 +51,33 @@ private:
 };
 
 
+/// A template struct, used to generate MoveStats and CounterMoveHistoryStats:
+/// MoveStats store the move that refute a previous one.
+/// CounterMoveHistoryStats is like HistoryStats, but with two consecutive moves.
+/// Entries are stored using only the moving piece and destination square, hence
+/// two moves with different origin but same destination and piece will be
+/// considered identical.
+template<typename T>
+struct Stats {
+  const T* operator[](Piece pc) const { return table[pc]; }
+  T* operator[](Piece pc) { return table[pc]; }
+  void clear() { std::memset(table, 0, sizeof(table)); }
+  void update(Piece pc, Square to, Move m) { table[pc][to] = m; }
+  void update(Piece pc, Square to, Value v) {
+
+    table[pc][to] -= table[pc][to] * abs(int(v)) / 936;
+    table[pc][to] += int(v) * 32;
+  }
+
+private:
+  T table[PIECE_NB][SQUARE_NB];
+};
+
+typedef Stats<Move> MoveStats;
+typedef Stats<Value> CounterMoveStats;
+typedef Stats<CounterMoveStats> CounterMoveHistoryStats;
+
+
 /// MovePicker class is used to pick one pseudo legal move at a time from the
 /// current position. The most important method is next_move(), which returns a
 /// new pseudo legal move each time it is called, until there are no moves left,
@@ -99,7 +95,7 @@ public:
   MovePicker(const Position&, Move, Depth, Square);
   MovePicker(const Position&, Move, Depth, Search::Stack*);
 
-  Move next_move();
+  Move next_move(bool skipQuiets = false);
 
 private:
   template<GenType> void score();