public static byte difference(UnsignedInt128 left, UnsignedInt128 right,
      UnsignedInt128 result) {
    return differenceInternal(left, right.v, result);
  }
Calculates absolute difference (remember that this is unsigned) of left and
right operator. <code>result := abs (left - right)</code> This is the core
implementation of subtract and signed add.

@param left
         left operand
@param right
         right operand
@param result
         the object to receive the result. can be same object as left or
         right.
@return signum of the result. -1 if left was smaller than right, 1 if
        larger, 0 if same (result is zero).
common/src/java/org/apache/hadoop/hive/common/type/UnsignedInt128.java