src/game.cpp

   1 /* PurpleHaze 2.0.0
   2  * Copyright (C) 2007-2011  Vincent Ollivier
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <assert.h>
  19 #include <iostream>
  20
  21 #include "game.h"
  22
  23 using namespace std;
  24
  25 Game::Game() {
  26     nodes_count = 0;
  27     output_thinking = false;
  28     tt.clear();
  29
  30     // Initialize MVV/LVA score array
  31     Moves::init_mvv_lva_scores();
  32 }
  33
  34 void Game::add_piece(Color c, PieceType t, Square s) {
  35     int i = pieces.get_nb_pieces(c, t);
  36     pieces.set_position(c, t, i, s);
  37     board.set_piece(Piece(c, t, i), s);
  38     pieces.inc_nb_pieces(c, t);
  39
  40     // Update Zobrist hash
  41     zobrist.update_piece(current_node().hash(), c, t, s);
  42 }
  43
  44 void Game::del_piece(Color c, PieceType t, int i) {
  45     // Remove the piece, and put in its place the higher index piece of the
  46     // same color and type in order to avoid holes (idea from Mediocre Chess)
  47     Square emptied = pieces.get_position(c, t, i); // Get piece's position
  48     board.set_piece(Piece(), emptied);             // Remove it from board
  49     pieces.dec_nb_pieces(c, t);                    // and from pieces list
  50     pieces.set_position(c, t, i, OUT);             // TODO: not needed
  51     int j = pieces.get_nb_pieces(c, t);            // Last piece's index
  52     if (pieces.get_nb_pieces(c, t) > 0 && i != j) {
  53         // Swap i and j and update board
  54         Square s = pieces.get_position(c, t, j);   // Last piece's position
  55         pieces.set_position(c, t, i, s);           // Fill the hole left
  56         pieces.set_position(c, t, j, OUT);         // TODO: not needed
  57         board.set_piece(Piece(c, t, i), s);        // Update board
  58     }
  59
  60     // Update Zobrist hash
  61     zobrist.update_piece(current_node().hash(), c, t, emptied);
  62 }
  63
  64 void Game::new_node() {
  65     // Take a "snapshot" of the current position
  66     tree.push();
  67
  68     // Remove the previous en passant square from the Zobrist hash
  69     zobrist.update_en_passant(current_node().hash(),
  70                               current_node().get_en_passant());
  71
  72     // Update the position for a new move
  73     current_node().inc_ply();
  74     current_node().change_side();
  75     zobrist.change_side(current_node().hash());
  76 }
  77
  78 void Game::del_node() {
  79     // Take back the previous "snapshot"
  80     tree.pop();
  81 }
  82
  83 /*
  84  * Killer move setter for the Killer Heuristic in move ordering.
  85  */
  86 void Game::set_killer_move(int depth, Move move) {
  87     if (move != killer_moves[depth][0]) {
  88         killer_moves[depth][1] = killer_moves[depth][0];
  89         killer_moves[depth][0] = move;
  90     }
  91 }