// changed June 15, 1999 by RL
// remove reference to Board (space,mflag)
// replaced with Board (Space, SetSpace, Flag, ang SetFlag)

// changed June 16, 1999 by RL
// change reference to from_row, from_col, to_row, to_col as methods
// change constructors for Move definitions

/**
  A simple move that just moves a piece from a source location
  to a destination location, possibly with a capture.
 */
class SimpleMove extends Move {
  // Piece that was previously at the destination.
  private int saved_piece;
  private int epsq;

  // Save the contents of the move flag for the source and destination
  // positions.
  boolean to_flag, from_flag;
  
  /**
    Construct a move that moves the piece from f_row, f_col to
    t_row, t_col
   */
  SimpleMove(Board b, int f_row, int f_col, int t_row, int t_col )
  {
    super(b, f_row, f_col, t_row, t_col);
  }
  
  /**
    Move a piece from the from position to the to position
   */
  public void apply( Board b )
  {
    // Make a copy of the target piece.

    saved_piece = b.Space(to_row(),to_col());
    epsq = b.getEPsq();
    b.setEPsq(0);
    if (piece() == Board.B_PAWN || piece() == Board.R_PAWN) {
       if (from_row()+2 == to_row()) b.setEPsq(((from_row()+1) << 3) | from_col());
       else if (from_row()-2 == to_row()) b.setEPsq(((from_row()-1) << 3) | from_col());
    }

    // Make copies of the source and destination move flags.
    to_flag = b.Flag(to_row(), to_col());
    from_flag = b.Flag(from_row(), from_col());
    
    // Flag these two spaces as having been moved.
    b.SetFlag(to_row(), to_col(), true);
    b.SetFlag(from_row(), from_col(), true);
    
    // Make a copy of the piece in the to position
    b.SetSpace(to_row(), to_col(), b.Space(from_row(), from_col()));

    // Empty the from position
    b.SetSpace(from_row(), from_col(), Board.EMPTY);

    // Added June 17, 1999 by RL
    if (!b.thinking()) display();

    // Added June 23, 1999 by RL
    b.GameHistory(pvCode());
  }

  /**
    Erase the mark from the space at row/col.
   */
  public void undo( Board b )
  {
    // Added June 23, 1999 by RL
    b.GameHistory(-1);

    // Restore the source and destination move flags
    b.SetFlag(to_row(), to_col(), to_flag);
    b.SetFlag(from_row(), from_col(), from_flag);
    
    // Put a copy of the piece in the back in the from position
    b.SetSpace(from_row(), from_col(), b.Space(to_row(), to_col()));

    // Empty the to position
    b.SetSpace(to_row(), to_col(), saved_piece);

    b.setEPsq(epsq);
  }
}



// change June 17, 1999 by RL
// changed to handle promotion to other pieces
/**
  A special move that moves a pawn and promotes it to a queen at the
  same time.  This code assumes that the pawn is stored as a value 
  of 1.
 */
class PromoteMove extends Move {
  // Piece that was previously at the destination.
  private int saved_piece;
  private int epsq;
  
  // Save the contents of the move flag for the source and destination
  // positions.
  boolean to_flag, from_flag;
  
  /**
    Construct a move that moves the piece from f_row, f_col to
    t_row, t_col
   */
  PromoteMove(Board b, int f_row, int f_col, int t_row, int t_col )
  {
    super(b, f_row, f_col, t_row, t_col, b.Space(f_row, f_col) * 
      Board.B_QUEEN);
  }
  
  // Added June 17, 1999 by RL
  /**
    Construct a move that moves the piece from f_row, f_col to
    t_row, t_col and promoted to a p_promote
   */
  PromoteMove(Board b, int f_row, int f_col, int t_row, int t_col, int p_promote )
  {
    super(b, f_row, f_col, t_row, t_col, p_promote);
  }
  /**
    Move a piece from the from position to the to position
   */
  public void apply( Board b )
  {
    // Make a copy of the saved piece.
    saved_piece = b.Space(to_row(), to_col());

    epsq = b.getEPsq();
    b.setEPsq(0);
    
    // Make copies of the source and destination move flags.
    to_flag = b.Flag(to_row(), to_col());
    from_flag = b.Flag(from_row(), from_col());

    // Flag these two spaces as having been moved.
    b.SetFlag(to_row(), to_col(), true);
    b.SetFlag(from_row(), from_col(), true);
    
    // Make a copy of the piece in the to position
    b.SetSpace(to_row(), to_col(), promote());

    // Empty the from position
    b.SetSpace(from_row(), from_col(), Board.EMPTY);

    // Added June 17, 1999 by RL
    if (!b.thinking()) display();

    // Added June 23, 1999 by RL
    b.GameHistory(pvCode());
  }

  /**
    Erase the mark from the space at row/col.
   */
  public void undo( Board b )
  {
    // Added June 23, 1999 by RL
    b.GameHistory(-1);

    // Put a copy of the piece in the back in the from position
    b.SetSpace(from_row(), from_col(), piece());

    // Restore the source and destination move flags
    b.SetFlag(to_row(), to_col(), to_flag);
    b.SetFlag(from_row(), from_col(), from_flag);
    
    // Empty the to position
    b.SetSpace(to_row(), to_col(), saved_piece);

    b.setEPsq(epsq);
  }

}

/**
  A CastleMove performs the castle operation between a king and the
  rook at the other end of the move.
 */
class CastleMove extends Move {
  int epsq;
  /**
    Construct a move that moves the piece from f_row, f_col to
    t_row, t_col
   */
  CastleMove(Board b, int f_row, int f_col, int t_row, int t_col )
  {
    super(b, f_row, f_col, t_row, t_col);
  }
  
  /**
    Move a piece from the from position to the to position
   */
  public void apply( Board b )
  {
    epsq = b.getEPsq();
    b.setEPsq(0);

    if( to_col() < from_col() ){
      b.SetSpace(to_row(), from_col() - 2, b.Space(from_row(), from_col()));
      b.SetSpace(to_row(), from_col() - 1, b.Space(to_row(), 0));

      // Original position of rook made empty.
      b.SetSpace(to_row(), 0, Board.EMPTY);

      // Flag rook space as having been moved.
      b.SetFlag(to_row(), 0, true);
    } else {
      b.SetSpace(to_row(), from_col() + 2, b.Space(from_row(), from_col()));
      b.SetSpace(to_row(), from_col() + 1, b.Space(to_row(), Board.WIDTH-1));

      // Original position of rook made empty.
      b.SetSpace(to_row(), Board.WIDTH-1, Board.EMPTY);

      // Flag rook space as having been moved.
      b.SetFlag(to_row(), Board.WIDTH-1, true);
    }

    // Original position king made empty.
    b.SetSpace(from_row(), from_col(), Board.EMPTY);

    // Flag king space as having been moved.
    b.SetFlag(from_row(), from_col(), true);


    // Added June 17, 1999 by RL
    if (!b.thinking()) display();

    // Added June 23, 1999 by RL
    b.GameHistory(pvCode());
  }

  /**
    Erase the mark from the space at row/col.
   */
  public void undo( Board b )
  {
    // Added June 23, 1999 by RL
    b.GameHistory(-1);

    // Restore the positions of the king and the rook.
    if( to_col() < from_col() ){
      b.SetSpace(to_row(), 0, b.Space(to_row(), from_col() - 1));
      b.SetSpace(from_row(), from_col(), b.Space(to_row(), from_col() - 2));

      b.SetSpace(to_row(), from_col() - 2, Board.EMPTY);
      b.SetSpace(to_row(), from_col() - 1, Board.EMPTY);

      // Restore the move flags for rook space
      b.SetFlag(to_row(), 0, false);
    } else {
      b.SetSpace(to_row(), Board.WIDTH-1, b.Space(to_row(), from_col() + 1));
      b.SetSpace(from_row(), from_col(), b.Space(to_row() ,from_col() + 2));

      b.SetSpace(to_row(), from_col() + 2, Board.EMPTY);
      b.SetSpace(to_row(), from_col() + 1, Board.EMPTY);

      // Restore the move flags for rook space
      b.SetFlag(to_row(), Board.WIDTH-1, false);
    }

    // Restore the move flags for king space
    b.SetFlag(from_row(), from_col(), false);

    b.setEPsq(epsq);
  }

  // Added June 16, 1999 by RL
  /**
     Return the captured piece.
   */
  public int captured()
  {
    return 0;
  }

  // Added June 17, 1999 by RL
  /**
     Make a string presentation of a Move.
   */
  public String string()
  {
    if( to_col() < from_col() )
      return "O-O-O";
    else
      return "O-O";
  }
}

/**
  A EPMove performs the en passant capture of pawn.
 */
class EPMove extends Move {
  int saved_piece;
  int  epsq;
  boolean from_flag, to_flag;

  /**
    Construct a move that moves the piece from f_row, f_col to
    t_row, t_col
   */
  EPMove(Board b, int f_row, int f_col, int t_row, int t_col )
  {
    super(b, f_row, f_col, t_row, t_col);
    epsq = b.getEPsq();
  }
  
  /**
    Move a piece from the from position to the to position
   */
  public void apply( Board b )
  {
    epsq = b.getEPsq();
    b.setEPsq(0);

    saved_piece = b.Space(from_row(), epsq & 07);
    b.SetSpace(from_row(), epsq & 07 , Board.EMPTY);
    b.SetSpace(to_row(), to_col() , piece());
    b.SetSpace(from_row(), from_col() , Board.EMPTY);


    // Flag these two spaces as having been moved.
    from_flag = b.Flag(from_row(), from_col());
    to_flag   = b.Flag(to_row(), to_col());
    b.SetFlag(from_row(), from_col(), true);
    b.SetFlag(to_row(), to_col(), true);

    // Added June 17, 1999 by RL
    if (!b.thinking()) display();

    // Added June 23, 1999 by RL
    b.GameHistory(pvCode());
  }

  /**
    Erase the mark from the space at row/col.
   */
  public void undo( Board b )
  {
    // Added June 23, 1999 by RL
    b.GameHistory(-1);

    b.SetSpace(from_row(), from_col() , piece());
    b.SetSpace(to_row(), to_col() , Board.EMPTY);
    b.SetSpace(from_row(), epsq & 07 , saved_piece);

    // Restore the move flags for these two spaces
    b.SetFlag(from_row(), from_col(), from_flag);
    b.SetFlag(to_row(), to_col(), to_flag);

    b.setEPsq(epsq);
  }


}


/**
  A fancy move generator that knows how to move every piece in chess.
 */
public class ChessGenerator extends Generator {

  // Generate all possible moves for the checker at position
  // row, col.  Add these moves to the front of move_list and return
  // the result.
  private Move movePawn( Move move_list, Board b, int side, 
                            int row, int col )
  {  
    // Pawns always move in the same direction, fortunately,
    // the side constant gives us the right direction.
    if( row + side >= 0 && row + side < Board.HEIGHT ){
      if( b.Space(row + side, col) == Board.EMPTY ){
        Move m;

        // See if we get to promote the pawn
        if( row + side == 0 || row + side == Board.HEIGHT - 1 )
          m = new PromoteMove( b, row, col, row + side, col );
        else
          m = new SimpleMove( b, row, col, row + side, col );
        m.next = move_list;
        move_list = m;
        
        // See if this is the pawn's first move or some later move.
        if( ( side == Board.B_SIDE && row == 1 ) || 
            ( side == Board.R_SIDE && row == 6 ) )
          if( b.Space(row + side * 2, col) == Board.EMPTY ){
            // Record the new move and link it into the move_list
            m = new SimpleMove( b, row, col, row + side * 2, col );
            m.next = move_list;
            move_list = m;
          }
      }

      // Consider capture moves
      // First, to the left.
      if( col > 0 && b.Space(row + side, col - 1) * side < 0 ){
        Move m;
        // See if we get to promote the pawn
        if( row + side == 0 || row + side == Board.HEIGHT - 1 )
          m = new PromoteMove( b, row, col, row + side, col - 1 );
        else
          m = new SimpleMove( b, row, col, row + side, col - 1 );
        m.next = move_list;
        move_list = m;
      }

      // Then to the right
      if( col + 1 < Board.WIDTH && 
          b.Space(row + side, col + 1) * side < 0 ){
        // Record the new move and link it into the move_list
        Move m;
        // See if we get to promote the pawn
        if( row + side == 0 || row + side == Board.HEIGHT - 1 )
          m = new PromoteMove( b, row, col, row + side, col + 1 );
        else
          m = new SimpleMove( b, row, col, row + side, col + 1 );
        m.next = move_list;
        move_list = m;
      }

      // e.p capture
      int epsq = b.getEPsq();
      if ( epsq > 0 && col + 1 < Board.WIDTH && 
           epsq == ( ((row+side) << 3) | (col + 1) ) ) {
        Move m = new EPMove( b, row, col, row + side, col + 1 );
        m.next = move_list;
        move_list = m;
      } else
      if ( epsq > 0 && col > 0 && 
           epsq == ( ((row+side) << 3) | (col - 1) ) ) {
        Move m = new EPMove( b, row, col, row + side, col - 1 );
        m.next = move_list;
        move_list = m;
      }

    }
    return move_list;
  }
  
  private Move moveKnight( Move move_list, Board b, int side, 
                           int row, int col )
  {
    if( row > 0 ){
      // See if the destination space is empty or has an enemy piece.
      if( col - 2 >= 0 && b.Space( row - 1, col - 2) * side <= 0 ){
        Move m = new SimpleMove( b, row, col, row - 1, col - 2 );
        m.next = move_list;
        move_list = m;
      }
      // See if the destination space is empty or has an enemy piece.
      if( col + 2 < Board.WIDTH && b.Space( row - 1, col + 2) * side <= 0 ){
        Move m = new SimpleMove( b, row, col, row - 1, col + 2 );
        m.next = move_list;
        move_list = m;
      }
      
      if( row - 1 > 0 ){
        // See if the destination space is empty or has an enemy piece.
        if( col > 0 && b.Space(row - 2, col - 1) * side <= 0 ){
          Move m = new SimpleMove( b, row, col, row - 2, col - 1 );
          m.next = move_list;
          move_list = m;
        } 
        // See if the destination space is empty or has an enemy piece.
        if( col + 1 < Board.WIDTH && b.Space(row - 2, col + 1) * side <= 0 ){
          Move m = new SimpleMove( b, row, col, row - 2, col + 1 );
          m.next = move_list;
          move_list = m;
        }
      }
    }
    
    if( row + 1 < Board.HEIGHT ){
      // See if the destination space is empty or has an enemy piece.
      if( col - 2 >= 0 && b.Space(row + 1, col - 2) * side <= 0 ){
        Move m = new SimpleMove( b, row, col, row + 1, col - 2 );
        m.next = move_list;
        move_list = m;
      }
      // See if the destination space is empty or has an enemy piece.
      if( col + 2 < Board.WIDTH && b.Space(row + 1 ,col + 2) * side <= 0 ){
        Move m = new SimpleMove( b, row, col, row + 1, col + 2 );
        m.next = move_list;
        move_list = m;
      }
      
      if( row + 2 < Board.HEIGHT ){
        // See if the destination space is empty or has an enemy piece.
        if( col > 0 && b.Space(row + 2, col - 1) * side <= 0 ){
          Move m = new SimpleMove( b, row, col, row + 2, col - 1 );
          m.next = move_list;
          move_list = m;
        } 
        // See if the destination space is empty or has an enemy piece.
        if( col + 1 < Board.WIDTH && b.Space(row + 2, col + 1)  * side <= 0 ){
          Move m = new SimpleMove( b, row, col, row + 2, col + 1 );
          m.next = move_list;
          move_list = m;
        }
      }
    }
    
    return move_list;
  }

  // Generate the moves for the king.  This is a little
  // tricky since the king can castle.
  private Move moveKing( Move move_list, Board b, int side, 
                           int row, int col )
  {
    // Move straight up or diagonal
    if( row > 0 ){
      if( b.Space( row - 1, col) * side <= 0 ){
        Move m = new SimpleMove( b, row, col, row - 1, col );
        m.next = move_list;
        move_list = m;
      }

      if( col > 0 && b.Space(row - 1 ,col - 1) * side <= 0 ){
        Move m = new SimpleMove( b, row, col, row - 1, col - 1 );
        m.next = move_list;
        move_list = m;
      }

      if( col + 1 < Board.WIDTH && b.Space(row - 1, col + 1) * side <= 0 ){
        Move m = new SimpleMove( b, row, col, row - 1, col + 1 );
        m.next = move_list;
        move_list = m;
      }
    }

    // Move straight down or diagonal
    if( row + 1 < Board.HEIGHT ){
      if( b.Space(row + 1, col) * side <= 0 ){
        Move m = new SimpleMove( b, row, col, row + 1, col );
        m.next = move_list;
        move_list = m;
      }

      if( col > 0 && b.Space( row + 1 , col - 1 ) * side <= 0 ){
        Move m = new SimpleMove( b, row, col, row + 1, col - 1 );
        m.next = move_list;
        move_list = m;
      }

      if( col + 1 < Board.WIDTH && b.Space( row + 1 , col + 1 ) * side <= 0 ){
        Move m = new SimpleMove( b, row, col, row + 1, col + 1 );
        m.next = move_list;
        move_list = m;
      }
    }

    // Move left or right
    if( col > 0 && b.Space( row , col - 1 ) * side <= 0 ){
      Move m = new SimpleMove( b, row, col, row, col - 1 );
      m.next = move_list;
      move_list = m;
    }

    if( col + 1 < Board.WIDTH && b.Space( row , col + 1 ) * side <= 0 ){
      Move m = new SimpleMove( b, row, col, row, col + 1 );
      m.next = move_list;
      move_list = m;
    }

    // Detect legal castle moves.
    if( b.Flag( row , col ) == false ){
      // See if we can castle to the left
      if( b.Flag( row , 0 ) == false ){
        // Make sure the path between the king and the rook is vacant.
        boolean vacant = true;
        for( int i = col - 1; i != 0; i-- )
          if( b.Space( row , i ) != Board.EMPTY )
            vacant = false;

        if( vacant ){
          // Now, the really expensive check.  Make sure none of the 
          // spaces on the way is threatened.
          for( int i = col; i != col - 3 && vacant; i-- )
            if( threatened( b, side, row, i ) )
              vacant = false;

          if( vacant ){
            // Move m = new CastleMove( b, row, col, row, 0 );
            Move m = new CastleMove( b, row, col, row, col-2 );
            m.next = move_list;
            move_list = m;
          }
        }
      }

      // See if we can castle to the right
      if( b.Flag( row , Board.WIDTH - 1 ) == false ){
        // Make sure the path between the king and the rook is vacant.
        boolean vacant = true;
        for( int i = col + 1; i != Board.WIDTH - 1; i++ )
          if( b.Space( row , i ) != Board.EMPTY )
            vacant = false;

        if( vacant ){
          // Now, the really expensive check.  Make sure none of the 
          // spaces on the way is threatened.
          for( int i = col; i != col + 3 && vacant; i++ )
            if( threatened( b, side, row, i ) )
              vacant = false;

          if( vacant ){
            // Move m = new CastleMove( b, row, col, row, Board.WIDTH - 1 );
            Move m = new CastleMove( b, row, col, row, col+2 );
            m.next = move_list;
            move_list = m;
          }
        }
      }
    }

    return move_list;
  }

  // Utility function for pieces that can move diagonally.
  // Concatenate moves onto the given move_list.
  protected Move moveDiagonal( Move move_list, Board b, int side,
                               int row, int col )
  {
    //left-up
    boolean NoPiece = true;
    int tmpcol = -1;
    int tmprow = -1;
    while (col + tmpcol >= 0 && row + tmprow >= 0 && NoPiece)
    { 	if (b.Space(row+tmprow,col+tmpcol) == 0)
    	{	Move m = new SimpleMove( b, row, col, row+tmprow, col+tmpcol);
	        m.next = move_list;
	        move_list = m;
	        tmpcol--;
	        tmprow--;
	    } else 
	    {
		    if (b.Space(row+tmprow,col+tmpcol) * side < 0)
		    {	Move m = new SimpleMove( b, row, col, row+tmprow, col+tmpcol);
		        m.next = move_list;
		        move_list = m;
		    }
		    NoPiece = false;
		}       
    }

    //right-up
    NoPiece = true;
    tmpcol = 1;
    tmprow = -1;
    while (col + tmpcol <= 7 && row + tmprow >= 0 && NoPiece)
    { 	if (b.Space(row+tmprow,col+tmpcol) == 0)
    	{	Move m = new SimpleMove( b, row, col, row+tmprow, col+tmpcol);
	        m.next = move_list;
	        move_list = m;
	        tmpcol++;
	        tmprow--;
	    } else 
	    {
		    if (b.Space(row+tmprow,col+tmpcol) * side < 0)
		    {	Move m = new SimpleMove( b, row, col, row+tmprow, col+tmpcol);
		        m.next = move_list;
		        move_list = m;
		    }
		    NoPiece = false;
		}       
    }


    //right-down
    NoPiece = true;
    tmpcol = 1;
    tmprow = 1;
    while (col + tmpcol <= 7 && row + tmprow <= 7 && NoPiece)
    { 	if (b.Space(row+tmprow,col+tmpcol) == 0)
    	{	Move m = new SimpleMove( b, row, col, row+tmprow, col+tmpcol);
	        m.next = move_list;
	        move_list = m;
	        tmpcol++;
	        tmprow++;
	    } else 
	    {
		    if (b.Space(row+tmprow,col+tmpcol) * side < 0)
		    {	Move m = new SimpleMove( b, row, col, row+tmprow, col+tmpcol);
		        m.next = move_list;
		        move_list = m;
		    }
		    NoPiece = false;
		}       
    }
 
    //left-down
    NoPiece = true;
    tmpcol = -1;
    tmprow = 1;
    while (col + tmpcol >= 0 && row + tmprow <= 7 && NoPiece)
    { 	if (b.Space(row+tmprow,col+tmpcol) == 0)
    	{	Move m = new SimpleMove( b, row, col, row+tmprow, col+tmpcol);
	        m.next = move_list;
	        move_list = m;
	        tmpcol--;
	        tmprow++;
	    } else 
	    {
		    if (b.Space(row+tmprow,col+tmpcol) * side < 0)
		    {	Move m = new SimpleMove( b, row, col, row+tmprow, col+tmpcol);
		        m.next = move_list;
		        move_list = m;
		    }
		    NoPiece = false;
		}       
    }

    return move_list;   
  }

  // Utility function for pieces that move in rows or columns
  // Insert moves into move_list
  protected Move moveRectangular( Move move_list, Board b, int side,
                                  int row, int col )
  {
    boolean NoPiece = true;
    //left
    int tmpcol = -1;
    while (col + tmpcol >= 0 && NoPiece)
    { 	if(b.Space(row,col+tmpcol) == 0)
    	{	Move m = new SimpleMove( b, row, col, row, col+tmpcol);
        	m.next = move_list;
	        move_list = m;
	        tmpcol--;
	     } else 
	     {
	     	if(b.Space(row,col+tmpcol) * side < 0)
	     	{ 	Move m = new SimpleMove( b, row, col, row, col+tmpcol);
	        	m.next = move_list;
		        move_list = m;
		    }
		    NoPiece = false;
		 }
	     
    }

    //up
    NoPiece = true;
    int tmprow = -1;
    while (row + tmprow >= 0 && NoPiece)
    { 	if(b.Space(row+tmprow,col) == 0)
    	{	Move m = new SimpleMove( b, row, col, row+tmprow, col);
        	m.next = move_list;
	        move_list = m;
	        tmprow--;
	     } else 
	     {
	     	if(b.Space(row+tmprow,col) * side < 0)
	     	{ 	Move m = new SimpleMove( b, row, col, row+tmprow, col);
	        	m.next = move_list;
		        move_list = m;
		    }
		    NoPiece = false;
		 }
	     
    }
   
    //right
    NoPiece = true;
    tmpcol = 1;
    while (col + tmpcol <= 7 && NoPiece)
    { 	if(b.Space(row,col+tmpcol) == 0)
    	{	Move m = new SimpleMove( b, row, col, row, col+tmpcol);
        	m.next = move_list;
	        move_list = m;
	        tmpcol++;
	     } else 
	     {
	     	if(b.Space(row,col+tmpcol) * side < 0)
	     	{ 	Move m = new SimpleMove( b, row, col, row, col+tmpcol);
	        	m.next = move_list;
		        move_list = m;
		    }
		    NoPiece = false;
		 }	     
    }
 
    //down
    NoPiece = true;
    tmprow = 1;
    while (row + tmprow <= 7 && NoPiece)
    { 	if(b.Space(row+tmprow,col) == 0)
    	{	Move m = new SimpleMove( b, row, col, row+tmprow, col);
        	m.next = move_list;
	        move_list = m;
	        tmprow++;
	     } else 
	     {
	     	if(b.Space(row+tmprow,col) * side < 0)
	     	{ 	Move m = new SimpleMove( b, row, col, row+tmprow, col);
	        	m.next = move_list;
		        move_list = m;
		    }
		    NoPiece = false;
		 }
	     
    }

    return move_list;   
  }

  // Return true if the given side is threatened (i.e. could a
  // piece at that space be captured.  This function is a bit
  // of a hack, but it should work for all of the standard pieces
  // in chess.
  private boolean threatened( Board b, int side, int row, int col )
  {
    Move move_list;
    Move m;
    
    // This tries each possible threat backward from the row, col
    // space.  Then it checks to see if there is the right kind
    // of piece at the to position to make that move back to the row, col
    // space.
    move_list = movePawn( null, b, side, row, col );
    for( m = move_list; m != null; m = m.next )
      if( b.Space( m.to_row() , m.to_col() ) * side == Board.R_PAWN )
        return true;

    move_list = moveRectangular( null, b, side, row, col );
    for( m = move_list; m != null; m = m.next )
      if( b.Space( m.to_row() , m.to_col() ) * side == Board.R_ROOK ||
          b.Space( m.to_row() , m.to_col() ) * side == Board.R_QUEEN )
        return true;

    move_list = moveDiagonal( null, b, side, row, col );
    for( m = move_list; m != null; m = m.next )
      if( b.Space( m.to_row() , m.to_col() ) * side == Board.R_BISHOP ||
          b.Space( m.to_row() , m.to_col() ) * side == Board.R_QUEEN )
        return true;

    move_list = moveKnight( null, b, side, row, col );
    for( m = move_list; m != null; m = m.next )
      if( b.Space( m.to_row() , m.to_col() ) * side == Board.R_KNIGHT )
        return true;

    // Temporarily set the moved flag so we don't try to castle from
    // inside this function
    boolean saved_flag = b.Flag( row , col );
    b.SetFlag( row , col , true);

    move_list = moveKing( null, b, side, row, col );
    for( m = move_list; m != null; m = m.next )
      if( b.Space( m.to_row() , m.to_col() ) * side == Board.R_KING ){
	b.SetFlag( row , col , saved_flag);
        return true;
      }
        
    b.SetFlag( row , col , saved_flag);

    return false;
  }

  public Move generateMoves( Board b, int side )
  {
    // Start out with an empty move list.
    Move move_list = null;

    // Check every space on the board.
    for( int row = 0; row < Board.HEIGHT; row++ )
      for( int col = 0; col < Board.WIDTH; col++ ){

        // See if this space contains a pawn for the given side.
        if( b.Space( row , col ) == Board.B_PAWN * side )
          move_list = movePawn( move_list, b, side, row, col );
          
        // See if this space contains a rook for the given side.
        if( b.Space( row , col ) == Board.B_ROOK * side )
          move_list = moveRectangular( move_list, b, side, row, col );
          
        if( b.Space( row , col ) == Board.B_KNIGHT * side )
          move_list = moveKnight( move_list, b, side, row, col );

        if( b.Space( row , col ) == Board.B_BISHOP * side )
          move_list = moveDiagonal( move_list, b, side, row, col );

        if( b.Space( row , col ) == Board.B_QUEEN * side ){
          // Queens move like rooks and like bishops
          move_list = moveDiagonal( move_list, b, side, row, col );
          move_list = moveRectangular( move_list, b, side, row, col );
        }

        if( b.Space( row , col ) == Board.B_KING * side )
          move_list = moveKing( move_list, b, side, row, col );
      }

    return move_list;
  }

}

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