private long floorToBucket(long logicalPosition){
  long d=(long)Math.floor(logicalPosition / bcktCapacity);
  return bcktCapacity * d;
}

private long floorToBucket ( long logicalPosition ) { long d = ( long ) Math . floor ( logicalPosition / bcktCapacity ) ; return bcktCapacity * d ; }
returns the largest position that is less than or equal to the argument and is equal to bucket base address .
