Subversion Repositories Games.Chess Giants

Rev

Rev 96 | Rev 169 | Go to most recent revision | Blame | Compare with Previous | Last modification | View Log | Download | RSS feed

  1. /*
  2.   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
  3.   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
  4.   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
  5.   Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
  6.  
  7.   Stockfish is free software: you can redistribute it and/or modify
  8.   it under the terms of the GNU General Public License as published by
  9.   the Free Software Foundation, either version 3 of the License, or
  10.   (at your option) any later version.
  11.  
  12.   Stockfish is distributed in the hope that it will be useful,
  13.   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15.   GNU General Public License for more details.
  16.  
  17.   You should have received a copy of the GNU General Public License
  18.   along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19. */
  20.  
  21. #ifndef MOVEPICK_H_INCLUDED
  22. #define MOVEPICK_H_INCLUDED
  23.  
  24. #include <algorithm> // For std::max
  25. #include <cstring>   // For std::memset
  26.  
  27. #include "movegen.h"
  28. #include "position.h"
  29. #include "types.h"
  30.  
  31.  
  32. /// The Stats struct stores moves statistics. According to the template parameter
  33. /// the class can store History and Countermoves. History records how often
  34. /// different moves have been successful or unsuccessful during the current search
  35. /// and is used for reduction and move ordering decisions.
  36. /// Countermoves store the move that refute a previous one. Entries are stored
  37. /// using only the moving piece and destination square, hence two moves with
  38. /// different origin but same destination and piece will be considered identical.
  39. template<typename T, bool CM = false>
  40. struct Stats {
  41.  
  42.   static const Value Max = Value(1 << 28);
  43.  
  44.   const T* operator[](Piece pc) const { return table[pc]; }
  45.   T* operator[](Piece pc) { return table[pc]; }
  46.   void clear() { std::memset(table, 0, sizeof(table)); }
  47.   void update(Piece pc, Square to, Move m) { table[pc][to] = m; }
  48.   void update(Piece pc, Square to, Value v) {
  49.  
  50.     if (abs(int(v)) >= 324)
  51.         return;
  52.  
  53.     table[pc][to] -= table[pc][to] * abs(int(v)) / (CM ? 936 : 324);
  54.     table[pc][to] += int(v) * 32;
  55.   }
  56.  
  57. private:
  58.   T table[PIECE_NB][SQUARE_NB];
  59. };
  60.  
  61. typedef Stats<Move> MoveStats;
  62. typedef Stats<Value, false> HistoryStats;
  63. typedef Stats<Value,  true> CounterMoveStats;
  64. typedef Stats<CounterMoveStats> CounterMoveHistoryStats;
  65.  
  66. struct FromToStats {
  67.  
  68.   Value get(Color c, Move m) const { return table[c][from_sq(m)][to_sq(m)]; }
  69.   void clear() { std::memset(table, 0, sizeof(table)); }
  70.   void update(Color c, Move m, Value v) {
  71.  
  72.     if (abs(int(v)) >= 324)
  73.         return;
  74.  
  75.     Square from = from_sq(m);
  76.     Square to = to_sq(m);
  77.  
  78.     table[c][from][to] -= table[c][from][to] * abs(int(v)) / 324;
  79.     table[c][from][to] += int(v) * 32;
  80.   }
  81.  
  82. private:
  83.   Value table[COLOR_NB][SQUARE_NB][SQUARE_NB];
  84. };
  85.  
  86.  
  87. /// MovePicker class is used to pick one pseudo legal move at a time from the
  88. /// current position. The most important method is next_move(), which returns a
  89. /// new pseudo legal move each time it is called, until there are no moves left,
  90. /// when MOVE_NONE is returned. In order to improve the efficiency of the alpha
  91. /// beta algorithm, MovePicker attempts to return the moves which are most likely
  92. /// to get a cut-off first.
  93. namespace Search { struct Stack; }
  94.  
  95. class MovePicker {
  96. public:
  97.   MovePicker(const MovePicker&) = delete;
  98.   MovePicker& operator=(const MovePicker&) = delete;
  99.  
  100.   MovePicker(const Position&, Move, Value);
  101.   MovePicker(const Position&, Move, Depth, Square);
  102.   MovePicker(const Position&, Move, Depth, Search::Stack*);
  103.  
  104.   Move next_move();
  105.  
  106. private:
  107.   template<GenType> void score();
  108.   ExtMove* begin() { return cur; }
  109.   ExtMove* end() { return endMoves; }
  110.  
  111.   const Position& pos;
  112.   const Search::Stack* ss;
  113.   Move countermove;
  114.   Depth depth;
  115.   Move ttMove;
  116.   Square recaptureSquare;
  117.   Value threshold;
  118.   int stage;
  119.   ExtMove *cur, *endMoves, *endBadCaptures;
  120.   ExtMove moves[MAX_MOVES];
  121. };
  122.  
  123. #endif // #ifndef MOVEPICK_H_INCLUDED
  124.