X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.h;h=ea599cda1afbe10a04f8a2f9f77ffc4becc237b8;hp=7a55e21c63cb8e38b1ccb187dc463ba5c85cdebb;hb=7d0a16e06d968c81f17140b0123db9768ce02a82;hpb=cf5d683408a2ef8a1c80be9bf7d6790a38b16277

diff --git a/src/movepick.h b/src/movepick.h
index 7a55e21c..ea599cda 100644
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -1,8 +1,6 @@
 /*
   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
+  Copyright (C) 2004-2021 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
@@ -80,16 +78,22 @@ struct Stats<T, D, Size> : public std::array<StatsEntry<T, D>, Size> {};
 
 /// In stats table, D=0 means that the template parameter is not used
 enum StatsParams { NOT_USED = 0 };
-
+enum StatsType { NoCaptures, Captures };
 
 /// ButterflyHistory records how often quiet moves have been successful or
 /// unsuccessful during the current search, and is used for reduction and move
 /// ordering decisions. It uses 2 tables (one for each color) indexed by
-/// the move's from and to squares, see chessprogramming.wikispaces.com/Butterfly+Boards
-typedef Stats<int16_t, 10692, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
+/// the move's from and to squares, see www.chessprogramming.org/Butterfly_Boards
+typedef Stats<int16_t, 13365, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
+
+/// At higher depths LowPlyHistory records successful quiet moves near the root
+/// and quiet moves which are/were in the PV (ttPv). It is cleared with each new
+/// search and filled during iterative deepening.
+constexpr int MAX_LPH = 4;
+typedef Stats<int16_t, 10692, MAX_LPH, int(SQUARE_NB) * int(SQUARE_NB)> LowPlyHistory;
 
 /// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
-/// move, see chessprogramming.wikispaces.com/Countermove+Heuristic
+/// move, see www.chessprogramming.org/Countermove_Heuristic
 typedef Stats<Move, NOT_USED, PIECE_NB, SQUARE_NB> CounterMoveHistory;
 
 /// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type]
@@ -104,12 +108,12 @@ typedef Stats<int16_t, 29952, PIECE_NB, SQUARE_NB> PieceToHistory;
 typedef Stats<PieceToHistory, NOT_USED, PIECE_NB, SQUARE_NB> ContinuationHistory;
 
 
-/// MovePicker class is used to pick one pseudo legal move at a time from the
+/// 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,
-/// when MOVE_NONE is returned. In order to improve the efficiency of the alpha
-/// beta algorithm, MovePicker attempts to return the moves which are most likely
-/// to get a cut-off first.
+/// new pseudo-legal move each time it is called, until there are no moves left,
+/// when MOVE_NONE is returned. In order to improve the efficiency of the
+/// alpha-beta algorithm, MovePicker attempts to return the moves which are most
+/// likely to get a cut-off first.
 class MovePicker {
 
   enum PickType { Next, Best };
@@ -123,10 +127,12 @@ public:
                                            const PieceToHistory**,
                                            Square);
   MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
+                                           const LowPlyHistory*,
                                            const CapturePieceToHistory*,
                                            const PieceToHistory**,
                                            Move,
-                                           Move*);
+                                           const Move*,
+                                           int);
   Move next_move(bool skipQuiets = false);
 
 private:
@@ -137,15 +143,16 @@ private:
 
   const Position& pos;
   const ButterflyHistory* mainHistory;
+  const LowPlyHistory* lowPlyHistory;
   const CapturePieceToHistory* captureHistory;
   const PieceToHistory** continuationHistory;
   Move ttMove;
   ExtMove refutations[3], *cur, *endMoves, *endBadCaptures;
   int stage;
-  Move move;
   Square recaptureSquare;
   Value threshold;
   Depth depth;
+  int ply;
   ExtMove moves[MAX_MOVES];
 };