Remove Stack/thread dependence in movepick

[stockfish] / src / movepick.h

diff --git a/src/movepick.h b/src/movepick.h
index 7d6651bb5da07c8c1bd87b9c6b26e7cb86384732..afd573ea459badabd1aa208b5d6dd498d49d455b 100644 (file)
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -1,7 +1,8 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, 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
@@ -17,38 +18,75 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#if !defined MOVEPICK_H_INCLUDED
+#ifndef MOVEPICK_H_INCLUDED
 #define MOVEPICK_H_INCLUDED
 
+#include <array>
+
+#include "movegen.h"
 #include "position.h"
-#include "search.h"
 #include "types.h"
 
+/// StatBoards is a generic 2-dimensional array used to store various statistics
+template<int Size1, int Size2, typename T = int>
+struct StatBoards : public std::array<std::array<T, Size2>, Size1> {
 
-/// The History class stores statistics about how often different moves
-/// have been successful or unsuccessful during the current search. These
-/// statistics are used for reduction and move ordering decisions. History
-/// entries are stored according only to moving piece and destination square,
-/// in particular two moves with different origin but same destination and
-/// same piece will be considered identical.
+  void fill(const T& v) {
+    T* p = &(*this)[0][0];
+    std::fill(p, p + sizeof(*this) / sizeof(*p), v);
+  }
+};
 
-class History {
-public:
+/// ButterflyBoards are 2 tables (one for each color) indexed by the move's from
+/// and to squares, see chessprogramming.wikispaces.com/Butterfly+Boards
+typedef StatBoards<COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyBoards;
 
-  static const Value Max = Value(2000);
+/// PieceToBoards are addressed by a move's [piece][to] information
+typedef StatBoards<PIECE_NB, SQUARE_NB> PieceToBoards;
 
-  const Value* operator[](Piece p) const { return &history[p][0]; }
-  Value gain(Piece p, Square to) const { return gains[p][to]; }
+/// 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 ButterflyBoards as backing store.
+struct ButterflyHistory : public ButterflyBoards {
 
-  void clear();
-  void update(Piece p, Square to, Value bonus);
-  void update_gain(Piece p, Square to, Value gain);
+  void update(Color c, Move m, int bonus) {
 
-private:
-  Value history[PIECE_NB][SQUARE_NB];
-  Value gains[PIECE_NB][SQUARE_NB];
+    const int D = 324;
+    auto& entry = (*this)[c][from_to(m)];
+
+    assert(abs(bonus) <= D); // Consistency check for below formula
+
+    entry += bonus * 32 - entry * abs(bonus) / D;
+
+    assert(abs(entry) <= 32 * D);
+  }
+};
+
+/// PieceToHistory is like ButterflyHistory, but is based on PieceToBoards
+struct PieceToHistory : public PieceToBoards {
+
+  void update(Piece pc, Square to, int bonus) {
+
+    const int D = 936;
+    auto& entry = (*this)[pc][to];
+
+    assert(abs(bonus) <= D); // Consistency check for below formula
+
+    entry += bonus * 32 - entry * abs(bonus) / D;
+
+    assert(abs(entry) <= 32 * D);
+  }
 };
 
+/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
+/// move, see chessprogramming.wikispaces.com/Countermove+Heuristic
+typedef StatBoards<PIECE_NB, SQUARE_NB, Move> CounterMoveHistory;
+
+/// ContinuationHistory is the history of a given pair of moves, usually the
+/// current one given a previous one. History table is based on PieceToBoards
+/// instead of ButterflyBoards.
+typedef StatBoards<PIECE_NB, SQUARE_NB, PieceToHistory> ContinuationHistory;
+
 
 /// 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
@@ -58,31 +96,29 @@ private:
 /// to get a cut-off first.
 
 class MovePicker {
-
-  MovePicker& operator=(const MovePicker&); // Silence a warning under MSVC
-
 public:
-  MovePicker(const Position&, Move, Depth, const History&, Search::Stack*, Value);
-  MovePicker(const Position&, Move, Depth, const History&, Square);
-  MovePicker(const Position&, Move, const History&, PieceType);
-  template<bool SpNode> Move next_move();
+  MovePicker(const MovePicker&) = delete;
+  MovePicker& operator=(const MovePicker&) = delete;
+  MovePicker(const Position&, Move, Value);
+  MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const PieceToHistory**, Square);
+  MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const PieceToHistory**, Move, Move*);
+  Move next_move(bool skipQuiets = false);
 
 private:
-  void score_captures();
-  void score_noncaptures();
-  void score_evasions();
-  void generate_next();
+  template<GenType> void score();
+  ExtMove* begin() { return cur; }
+  ExtMove* end() { return endMoves; }
 
   const Position& pos;
-  const History& H;
-  Search::Stack* ss;
-  Depth depth;
-  Move ttMove;
-  MoveStack killers[2];
+  const ButterflyHistory* mainHistory;
+  const PieceToHistory** contHistory;
+  Move ttMove, countermove, killers[2];
+  ExtMove *cur, *endMoves, *endBadCaptures;
+  int stage;
   Square recaptureSquare;
-  int captureThreshold, phase;
-  MoveStack *cur, *end, *endQuiets, *endBadCaptures;
-  MoveStack moves[MAX_MOVES];
+  Value threshold;
+  Depth depth;
+  ExtMove moves[MAX_MOVES];
 };
 
-#endif // !defined(MOVEPICK_H_INCLUDED)
+#endif // #ifndef MOVEPICK_H_INCLUDED