Introduce capture history table for capture move sorting

[stockfish] / src / movepick.h

diff --git a/src/movepick.h b/src/movepick.h
index 66fc1bdba4a929bd1680eeb5715a9786581881f2..db9439f715ed1860718f712d9afb855987117fd9 100644 (file)
--- a/src/movepick.h
+++ b/src/movepick.h
@@ -22,6 +22,7 @@
 #define MOVEPICK_H_INCLUDED
 
 #include <array>
+#include <limits>
 
 #include "movegen.h"
 #include "position.h"
@@ -39,7 +40,7 @@ struct StatBoards : public std::array<std::array<T, Size2>, Size1> {
   void update(T& entry, int bonus, const int D) {
 
     assert(abs(bonus) <= D); // Ensure range is [-32 * D, 32 * D]
-    assert(abs(32 * D) < INT16_MAX); // Ensure we don't overflow
+    assert(abs(32 * D) < (std::numeric_limits<T>::max)()); // Ensure we don't overflow
 
     entry += bonus * 32 - entry * abs(bonus) / D;
 
@@ -47,6 +48,26 @@ struct StatBoards : public std::array<std::array<T, Size2>, Size1> {
   }
 };
 
+/// StatCubes is a generic 3-dimensional array used to store various statistics
+template<int Size1, int Size2, int Size3, typename T = int16_t>
+struct StatCubes : public std::array<std::array<std::array<T, Size3>, Size2>, Size1> {
+
+  void fill(const T& v) {
+    T* p = &(*this)[0][0][0];
+    std::fill(p, p + sizeof(*this) / sizeof(*p), v);
+  }
+
+  void update(T& entry, int bonus, const int D, const int W) {
+
+    assert(abs(bonus) <= D); // Ensure range is [-W * D, W * D]
+    assert(abs(W * D) < (std::numeric_limits<T>::max)()); // Ensure we don't overflow
+
+    entry += bonus * W - entry * abs(bonus) / D;
+
+    assert(abs(entry) <= W * D);
+  }
+};
+
 /// 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;
@@ -54,6 +75,9 @@ typedef StatBoards<COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyBoards;
 /// PieceToBoards are addressed by a move's [piece][to] information
 typedef StatBoards<PIECE_NB, SQUARE_NB> PieceToBoards;
 
+/// CapturePieceToBoards are addressed by a move's [piece][to][captured piece type] information
+typedef StatCubes<PIECE_NB, SQUARE_NB, PIECE_TYPE_NB> CapturePieceToBoards;
+
 /// 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.
@@ -72,6 +96,14 @@ struct PieceToHistory : public PieceToBoards {
   }
 };
 
+/// CapturePieceToHistory is like PieceToHistory, but is based on CapturePieceToBoards
+struct CapturePieceToHistory : public CapturePieceToBoards {
+
+  void update(Piece pc, Square to, PieceType captured, int bonus) {
+    StatCubes::update((*this)[pc][to][captured], bonus, 324, 2);
+  }
+};
+
 /// 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;
@@ -93,9 +125,9 @@ class MovePicker {
 public:
   MovePicker(const MovePicker&) = delete;
   MovePicker& operator=(const MovePicker&) = delete;
-  MovePicker(const Position&, Move, Value);
-  MovePicker(const Position&, Move, Depth, const ButterflyHistory*, 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*, Square);
+  MovePicker(const Position&, Move, Depth, const ButterflyHistory*, const CapturePieceToHistory*, const PieceToHistory**, Move, Move*);
   Move next_move(bool skipQuiets = false);
 
 private:
@@ -105,6 +137,7 @@ private:
 
   const Position& pos;
   const ButterflyHistory* mainHistory;
+  const CapturePieceToHistory* captureHistory;
   const PieceToHistory** contHistory;
   Move ttMove, countermove, killers[2];
   ExtMove *cur, *endMoves, *endBadCaptures;