Subversion Repositories Games.Chess Giants

#include "chess.h"

#include "data.h"

/* last modified 01/06/16 */

/*

 *******************************************************************************

 *                                                                             *

 *   MakeMove() is responsible for updating the position database whenever a   *

 *   piece is moved.  It performs the following operations:  (1) update the    *

 *   board structure itself by moving the piece and removing any captured      *

 *   piece.  (2) update the hash keys.  (3) update material counts.  (4) then  *

 *   update castling status.  (5) and finally update number of moves since     *

 *   last reversible move.                                                     *

 *                                                                             *

 *   There are some special-cases handled here, such as en passant captures    *

 *   where the enemy pawn is not on the <target> square, castling which moves  *

 *   both the king and rook, and then rook moves/captures which give up the    *

 *   castling right to that side when the rook is moved.                       *

 *                                                                             *

 *   note:  side = 1 if white is to move, 0 otherwise.  enemy is the opposite  *

 *   and is 1 if it is not white to move, 0 otherwise.                         *

 *                                                                             *

 *******************************************************************************

 */

void MakeMove(TREE * RESTRICT tree, int ply, int side, int move) {

  uint64_t bit_move;

  int piece, from, to, captured, promote, enemy = Flip(side), cpiece;

#if defined(DEBUG)

  int i;

#endif

/*

 ************************************************************

 *                                                          *

 *  First, some basic information is updated for all moves  *

 *  before we do the piece-specific stuff.  We need to save *

 *  the current position and both hash signatures, and add  *

 *  the current position to the repetition-list for the     *

 *  side on move, before the move is actually made on the   *

 *  board.  We also update the 50 move rule counter which   *

 *  will be reset if a capture or pawn move is made here.   *

 *                                                          *

 *  If the en passant flag was set the previous ply, we     *

 *  have already used it to generate moves at this ply and  *

 *  we need to clear it before continuing.  If it is set,   *

 *  we also need to update the hash signature since the EP  *

 *  opportunity no longer exists after making any move at   *

 *  this ply (one ply deeper than when a pawn was advanced  *

 *  two squares).                                           *

 *                                                          *

 ************************************************************

 */

#if defined(DEBUG)

  ValidatePosition(tree, ply, move, "MakeMove(1)");

#endif

  tree->status[ply + 1] = tree->status[ply];

  tree->save_hash_key[ply] = HashKey;

  tree->save_pawn_hash_key[ply] = PawnHashKey;

  if (EnPassant(ply + 1)) {

    HashEP(EnPassant(ply + 1));

    EnPassant(ply + 1) = 0;

  }

  Reversible(ply + 1)++;

/*

 ************************************************************

 *                                                          *

 *  Now do the things that are common to all pieces, such   *

 *  as updating the bitboards and hash signature.           *

 *                                                          *

 ************************************************************

 */

  piece = Piece(move);

  from = From(move);

  to = To(move);

  captured = Captured(move);

  promote = Promote(move);

  bit_move = SetMask(from) | SetMask(to);

  cpiece = PcOnSq(to);

  ClearSet(bit_move, Pieces(side, piece));

  ClearSet(bit_move, Occupied(side));

  Hash(side, piece, from);

  Hash(side, piece, to);

  PcOnSq(from) = 0;

  PcOnSq(to) = pieces[side][piece];

/*

 ************************************************************

 *                                                          *

 *  Now do the piece-specific things by jumping to the      *

 *  appropriate routine.                                    *

 *                                                          *

 ************************************************************

 */

  switch (piece) {

    case pawn:

      HashP(side, from);

      HashP(side, to);

      Reversible(ply + 1) = 0;

      if (captured == 1 && !cpiece) {

        Clear(to + epsq[side], Pawns(enemy));

        Clear(to + epsq[side], Occupied(enemy));

        Hash(enemy, pawn, to + epsq[side]);

        HashP(enemy, to + epsq[side]);

        PcOnSq(to + epsq[side]) = 0;

        Material -= PieceValues(enemy, pawn);

        TotalPieces(enemy, pawn)--;

        TotalAllPieces--;

        captured = 0;

      }

      if (promote) {

        TotalPieces(side, pawn)--;

        Material -= PieceValues(side, pawn);

        Clear(to, Pawns(side));

        Hash(side, pawn, to);

        HashP(side, to);

        Hash(side, promote, to);

        PcOnSq(to) = pieces[side][promote];

        TotalPieces(side, occupied) += p_vals[promote];

        TotalPieces(side, promote)++;

        Material += PieceValues(side, promote);

        Set(to, Pieces(side, promote));

      } else if ((Abs(to - from) == 16) && (mask_eptest[to] & Pawns(enemy))) {

        EnPassant(ply + 1) = to + epsq[side];

        HashEP(to + epsq[side]);

      }

      break;

    case knight:

    case bishop:

    case queen:

      break;

    case rook:

      if (Castle(ply + 1, side) > 0) {

        if ((from == rook_A[side]) && (Castle(ply + 1, side) & 2)) {

          Castle(ply + 1, side) &= 1;

          HashCastle(1, side);

        } else if ((from == rook_H[side]) && (Castle(ply + 1, side) & 1)) {

          Castle(ply + 1, side) &= 2;

          HashCastle(0, side);

        }

      }

      break;

    case king:

      KingSQ(side) = to;

      if (Castle(ply + 1, side) > 0) {

        if (Castle(ply + 1, side) & 2)

          HashCastle(1, side);

        if (Castle(ply + 1, side) & 1)

          HashCastle(0, side);

        if (Abs(to - from) == 2) {

          Castle(ply + 1, side) = -1;

          piece = rook;

          if (to == rook_G[side]) {

            from = rook_H[side];

            to = rook_F[side];

          } else {

            from = rook_A[side];

            to = rook_D[side];

          }

          bit_move = SetMask(from) | SetMask(to);

          ClearSet(bit_move, Rooks(side));

          ClearSet(bit_move, Occupied(side));

          Hash(side, rook, from);

          Hash(side, rook, to);

          PcOnSq(from) = 0;

          PcOnSq(to) = pieces[side][rook];

        } else

          Castle(ply + 1, side) = 0;

      }

      break;

  }

/*

 ************************************************************

 *                                                          *

 *  If this is a capture move, we also have to update the   *

 *  information that must change when a piece is removed    *

 *  from the board.                                         *

 *                                                          *

 ************************************************************

 */

  if (captured) {

    Reversible(ply + 1) = 0;

    TotalAllPieces--;

    if (promote)

      piece = promote;

    Hash(enemy, captured, to);

    Clear(to, Pieces(enemy, captured));

    Clear(to, Occupied(enemy));

    Material -= PieceValues(enemy, captured);

    TotalPieces(enemy, captured)--;

    if (captured != pawn)

      TotalPieces(enemy, occupied) -= p_vals[captured];

    switch (captured) {

      case pawn:

        HashP(enemy, to);

        break;

      case knight:

      case bishop:

      case queen:

        break;

      case rook:

        if (Castle(ply + 1, enemy) > 0) {

          if ((to == rook_A[enemy]) && (Castle(ply + 1, enemy) & 2)) {

            Castle(ply + 1, enemy) &= 1;

            HashCastle(1, enemy);

          } else if ((to == rook_H[enemy]) && (Castle(ply + 1, enemy) & 1)) {

            Castle(ply + 1, enemy) &= 2;

            HashCastle(0, enemy);

          }

        }

        break;

      case king:

#if defined(DEBUG)

        Print(2048, "captured a king (Make)\n");

        for (i = 1; i <= ply; i++)

          Print(2048,

              "ply=%2d, phase=%d, piece=%2d,from=%2d,to=%2d,captured=%2d\n",

              i, tree->phase[i], Piece(tree->curmv[i]), From(tree->curmv[i]),

              To(tree->curmv[i]), Captured(tree->curmv[i]));

        Print(2048, "ply=%2d, piece=%2d,from=%2d,to=%2d,captured=%2d\n", i,

            piece, from, to, captured);

        if (log_file)

          DisplayChessBoard(log_file, tree->position);

#endif

        break;

    }

  }

#if defined(DEBUG)

  ValidatePosition(tree, ply + 1, move, "MakeMove(2)");

#endif

  return;

}

/* last modified 01/06/16 */

/*

 *******************************************************************************

 *                                                                             *

 *   MakeMoveRoot() is used to make a move at the root of the game tree,       *

 *   before any searching is done.  It uses MakeMove() to execute the move,    *

 *   but then copies the resulting position back to position[0], the actual    *

 *   board position.  It handles the special-case of the draw-by-repetition    *

 *   rule by clearing the repetition list when a non-reversible move is made,  *

 *   since no repetitions are possible once such a move is played.             *

 *                                                                             *

 *******************************************************************************

 */

void MakeMoveRoot(TREE * RESTRICT tree, int side, int move) {

  int player;

/*

 ************************************************************

 *                                                          *

 *  First, make the move and then reset the repetition      *

 *  index if the 50 move rule counter was reset to zero.    *

 *                                                          *

 ************************************************************

 */

  MakeMove(tree, 0, side, move);

  if (Reversible(1) == 0)

    rep_index = -1;

  tree->rep_list[++rep_index] = HashKey;

/*

 ************************************************************

 *                                                          *

 *  One odd action is to note if the castle status is       *

 *  currently negative, which indicates that that side      *

 *  castled during the previous search.  We simply set the  *

 *  castle status for that side to zero and we are done.    *

 *                                                          *

 *  We then copy this back to ply=0 status (which is the    *

 *  permanent game-board ply).                              *

 *                                                          *

 ************************************************************

 */

  for (player = black; player <= white; player++)

    Castle(1, player) = Max(0, Castle(1, player));

  tree->status[0] = tree->status[1];

}