private short bitLength() {
    return SqlMathUtil.bitLength(v[0], v[1], v[2], v[3]);
  }
This version returns the result as a new object, not modifying the give
objects.

@param bits
         the number of bits. must be positive
@return operation result as a new object
common/src/java/org/apache/hadoop/hive/common/type/UnsignedInt128.java