src/search.h

   1 /* Copyright (C) 2007-2011 Vincent Ollivier
   2  *
   3  * Purple Haze is free software: you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation, either version 3 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * Purple Haze is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  15  */
  16
  17 #ifndef SEARCH_H
  18 #define SEARCH_H
  19
  20 #include "common.h"
  21 #include "eval.h"
  22
  23 enum NodeType : unsigned char { PV, CUT, ALL };
  24
  25 // Adaptive Null-Move Pruning (Heinz 1999)
  26 inline static int R_ADAPT(int d, int n)
  27 {
  28     return 2 + (d > (6 + ((n < 3) ? 2 : 0)));
  29 }
  30
  31 static const int R = 2;
  32 static const int NMP_DEPTH = 3;      // depth > NMP_DEPTH
  33 static const int LMR_DEPTH = 2;      // depth > LMR_DEPTH
  34 static const int IID_DEPTH = 3;      // depth > IID_DEPTH
  35 static const int FUTILITY_DEPTH = 3; // depth <= FUTILITY_DEPTH
  36
  37 // Array of pruning margin values indexed by depth. Idea from Crafty
  38 static const int FUTILITY_MARGINS[FUTILITY_DEPTH + 1] = {
  39     0,
  40     PIECE_VALUE[PAWN],
  41     PIECE_VALUE[KNIGHT],
  42     PIECE_VALUE[ROOK]
  43 };
  44
  45 inline static int value_to_trans(int value, int ply)
  46 {
  47     if (value < -INF + MAX_PLY) {
  48         value -= ply;
  49     } else if (value > INF - MAX_PLY) {
  50         value += ply;
  51     }
  52     return value;
  53 }
  54
  55 inline static int value_from_trans(int value, int ply)
  56 {
  57     if (value < -INF + MAX_PLY) {
  58         value += ply;
  59     } else if (value > INF - MAX_PLY) {
  60         value -= ply;
  61     }
  62     return value;
  63 }
  64
  65 #endif /* !SEARCH_H */