private static int toHashCode(ChessDrawType drawType, ChessColor drawingSide, ChessPieceType drawingPieceType, ChessPieceType?takenPieceType,
ChessPieceType?promotionPieceType, ChessPosition oldPosition, ChessPosition newPosition, bool isFirstMove)
{
// TODO: try to remove if/else branchings to make this more efficient
// shift the bits to the right position (preparation for bitwise OR)
int isFirstMoveBits = (isFirstMove ? 1 : 0) << IS_FIRST_MOVE_TRAILING_BITS;
int drawTypeBits = ((int)drawType) << DRAW_TYPE_TRAILING_BITS;
int drawingSideBits = ((int)drawingSide) << DRAWING_SIDE_TRAILING_BITS;
int drawingPieceTypeBits = ((int)drawingPieceType) << DRAWING_PIECE_TYPE_TRAILING_BITS;
int takenPieceTypeBits = ((takenPieceType != null) ? (int)takenPieceType.Value : CHESS_PIECE_TYPE_NULL) << TAKEN_PIECE_TYPE_TRAILING_BITS;
int promotionPieceTypeBits = ((promotionPieceType != null) ? (int)promotionPieceType.Value : CHESS_PIECE_TYPE_NULL) << PROMOTION_PIECE_TYPE_TRAILING_BITS;
int oldPositionBits = oldPosition.GetHashCode() << OLD_POSITION_TRAILING_BITS;
int newPositionBits = newPosition.GetHashCode();
// fuse the shifted bits to the hash code (by bitwise OR)
int hashCode = (isFirstMoveBits | drawTypeBits | drawingSideBits | drawingPieceTypeBits
| takenPieceTypeBits | promotionPieceTypeBits | oldPositionBits | newPositionBits);
return(hashCode);
}
public ChessPieceAtPos(ChessPosition position, ChessPiece piece)
{
_hashCode = (short)((position.GetHashCode() << 5) | piece.GetHashCode());
}
