src/movepick.h

   1 /*
   2   Glaurung, a UCI chess playing engine.
   3   Copyright (C) 2004-2008 Tord Romstad
   4
   5   Glaurung is free software: you can redistribute it and/or modify
   6   it under the terms of the GNU General Public License as published by
   7   the Free Software Foundation, either version 3 of the License, or
   8   (at your option) any later version.
   9
  10   Glaurung is distributed in the hope that it will be useful,
  11   but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13   GNU General Public License for more details.
  14
  15   You should have received a copy of the GNU General Public License
  16   along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19
  20 #if !defined MOVEPICK_H_INCLUDED
  21 #define MOVEPICK_H_INCLUDED
  22
  23 ////
  24 //// Includes
  25 ////
  26
  27 #include "depth.h"
  28 #include "lock.h"
  29 #include "position.h"
  30
  31
  32 ////
  33 //// Types
  34 ////
  35
  36 /// MovePicker is a class which is used to pick one legal move at a time from
  37 /// the current position.  It is initialized with a Position object and a few
  38 /// moves we have reason to believe are good.  The most important method is
  39 /// MovePicker::pick_next_move(), which returns a new legal move each time it
  40 /// is called, until there are no legal moves left, when MOVE_NONE is returned.
  41 /// In order to improve the efficiency of the alpha beta algorithm, MovePicker
  42 /// attempts to return the moves which are most likely to be strongest first.
  43
  44 class MovePicker {
  45
  46 public:
  47
  48   enum MovegenPhase {
  49     PH_TT_MOVE,        // Transposition table move
  50     PH_MATE_KILLER,    // Mate killer from the current ply
  51     PH_GOOD_CAPTURES,  // Queen promotions and captures with SEE values >= 0
  52     PH_BAD_CAPTURES,   // Queen promotions and captures with SEE valuse <= 0
  53     PH_KILLER_1,       // Killer move 1 from the current ply (not used yet).
  54     PH_KILLER_2,       // Killer move 2 from the current ply (not used yet).
  55     PH_NONCAPTURES,    // Non-captures and underpromotions
  56     PH_EVASIONS,       // Check evasions
  57     PH_QCAPTURES,      // Captures in quiescence search
  58     PH_QCHECKS,        // Checks in quiescence search
  59     PH_STOP
  60   };
  61
  62   MovePicker(Position &p, bool pvnode, Move ttm, Move mk, Move k1, Move k2,
  63              Depth dpth);
  64   Move get_next_move();
  65   Move get_next_move(Lock &lock);
  66   int number_of_moves() const;
  67   int current_move_score() const;
  68   MovegenPhase current_move_type() const;
  69   Bitboard discovered_check_candidates() const;
  70
  71   static void init_phase_table();
  72
  73 private:
  74   void score_captures();
  75   void score_noncaptures();
  76   void score_evasions();
  77   void score_qcaptures();
  78   Move pick_move_from_list();
  79
  80   Position *pos;
  81   Move ttMove, mateKiller, killer1, killer2;
  82   Bitboard pinned, dc;
  83   MoveStack moves[256], badCaptures[64];
  84   static MovegenPhase PhaseTable[32];
  85   bool pvNode;
  86   Depth depth;
  87   int phaseIndex;
  88   int numOfMoves, numOfBadCaptures;
  89   int movesPicked, badCapturesPicked;
  90   bool finished;
  91 };
  92
  93
  94 ////
  95 //// Inline functions
  96 ////
  97
  98 /// MovePicker::discovered_check_candidates() returns a bitboard containing
  99 /// all pieces which can possibly give discovered check.  This bitboard is
 100 /// computed by the constructor function.
 101
 102 inline MovePicker::MovegenPhase MovePicker::current_move_type() const {
 103   return PhaseTable[phaseIndex];
 104 }
 105
 106 inline Bitboard MovePicker::discovered_check_candidates() const {
 107   return dc;
 108 }
 109
 110 #endif // !defined(MOVEPICK_H_INCLUDED)