X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmovepick.h;h=e916514dfd146a3a0a1a18ebdd6c75330ec38b28;hp=afd573ea459badabd1aa208b5d6dd498d49d455b;hb=c4fc00ec49d748f1ec1cd2fa2affa73bfdc86f8f;hpb=b40e45c1cc51bd228898314264d6d241478b23d8

diff --git a/src/movepick.h b/src/movepick.h
index afd573ea..e916514d 100644
--- 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) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, 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
@@ -22,70 +22,86 @@
 #define MOVEPICK_H_INCLUDED
 
 #include <array>
+#include <limits>
+#include <type_traits>
 
 #include "movegen.h"
 #include "position.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> {
+/// StatsEntry stores the stat table value. It is usually a number but could
+/// be a move or even a nested history. We use a class instead of naked value
+/// to directly call history update operator<<() on the entry so to use stats
+/// tables at caller sites as simple multi-dim arrays.
+template<typename T, int D>
+class StatsEntry {
 
-  void fill(const T& v) {
-    T* p = &(*this)[0][0];
-    std::fill(p, p + sizeof(*this) / sizeof(*p), v);
-  }
-};
+  T entry;
 
-/// 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;
+public:
+  void operator=(const T& v) { entry = v; }
+  T* operator&() { return &entry; }
+  T* operator->() { return &entry; }
+  operator const T&() const { return entry; }
 
-/// PieceToBoards are addressed by a move's [piece][to] information
-typedef StatBoards<PIECE_NB, SQUARE_NB> PieceToBoards;
+  void operator<<(int bonus) {
+    assert(abs(bonus) <= D); // Ensure range is [-D, D]
+    static_assert(D <= std::numeric_limits<T>::max(), "D overflows T");
 
-/// 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 {
+    entry += bonus - entry * abs(bonus) / D;
 
-  void update(Color c, Move m, int bonus) {
+    assert(abs(entry) <= D);
+  }
+};
 
-    const int D = 324;
-    auto& entry = (*this)[c][from_to(m)];
+/// Stats is a generic N-dimensional array used to store various statistics.
+/// The first template parameter T is the base type of the array, the second
+/// template parameter D limits the range of updates in [-D, D] when we update
+/// values with the << operator, while the last parameters (Size and Sizes)
+/// encode the dimensions of the array.
+template <typename T, int D, int Size, int... Sizes>
+struct Stats : public std::array<Stats<T, D, Sizes...>, Size>
+{
+  typedef Stats<T, D, Size, Sizes...> stats;
 
-    assert(abs(bonus) <= D); // Consistency check for below formula
+  void fill(const T& v) {
 
-    entry += bonus * 32 - entry * abs(bonus) / D;
+    // For standard-layout 'this' points to first struct member
+    assert(std::is_standard_layout<stats>::value);
 
-    assert(abs(entry) <= 32 * D);
+    typedef StatsEntry<T, D> entry;
+    entry* p = reinterpret_cast<entry*>(this);
+    std::fill(p, p + sizeof(*this) / sizeof(entry), v);
   }
 };
 
-/// PieceToHistory is like ButterflyHistory, but is based on PieceToBoards
-struct PieceToHistory : public PieceToBoards {
+template <typename T, int D, int Size>
+struct Stats<T, D, Size> : public std::array<StatsEntry<T, D>, Size> {};
 
-  void update(Piece pc, Square to, int bonus) {
+/// In stats table, D=0 means that the template parameter is not used
+enum StatsParams { NOT_USED = 0 };
 
-    const int D = 936;
-    auto& entry = (*this)[pc][to];
 
-    assert(abs(bonus) <= D); // Consistency check for below formula
+/// 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 www.chessprogramming.org/Butterfly_Boards
+typedef Stats<int16_t, 10692, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
 
-    entry += bonus * 32 - entry * abs(bonus) / D;
+/// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
+/// move, see www.chessprogramming.org/Countermove_Heuristic
+typedef Stats<Move, NOT_USED, PIECE_NB, SQUARE_NB> CounterMoveHistory;
 
-    assert(abs(entry) <= 32 * D);
-  }
-};
+/// CapturePieceToHistory is addressed by a move's [piece][to][captured piece type]
+typedef Stats<int16_t, 10692, PIECE_NB, SQUARE_NB, PIECE_TYPE_NB> CapturePieceToHistory;
 
-/// 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;
+/// PieceToHistory is like ButterflyHistory but is addressed by a move's [piece][to]
+typedef Stats<int16_t, 29952, PIECE_NB, SQUARE_NB> PieceToHistory;
 
-/// 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;
+/// ContinuationHistory is the combined history of a given pair of moves, usually
+/// the current one given a previous one. The nested history table is based on
+/// PieceToHistory instead of ButterflyBoards.
+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
@@ -94,26 +110,37 @@ typedef StatBoards<PIECE_NB, SQUARE_NB, PieceToHistory> ContinuationHistory;
 /// 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 };
+
 public:
   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*);
+  MovePicker(const Position&, Move, Value, const CapturePieceToHistory*);
+  MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
+                                           const CapturePieceToHistory*,
+                                           const PieceToHistory**,
+                                           Square);
+  MovePicker(const Position&, Move, Depth, const ButterflyHistory*,
+                                           const CapturePieceToHistory*,
+                                           const PieceToHistory**,
+                                           Move,
+                                           Move*);
   Move next_move(bool skipQuiets = false);
 
 private:
+  template<PickType T, typename Pred> Move select(Pred);
   template<GenType> void score();
   ExtMove* begin() { return cur; }
   ExtMove* end() { return endMoves; }
 
   const Position& pos;
   const ButterflyHistory* mainHistory;
-  const PieceToHistory** contHistory;
-  Move ttMove, countermove, killers[2];
-  ExtMove *cur, *endMoves, *endBadCaptures;
+  const CapturePieceToHistory* captureHistory;
+  const PieceToHistory** continuationHistory;
+  Move ttMove;
+  ExtMove refutations[3], *cur, *endMoves, *endBadCaptures;
   int stage;
   Square recaptureSquare;
   Value threshold;