code: protected static final int findSameIndexBlock(int index[], int indexLength,
                                                    int otherBlock) 
      {
          for (int block = BMP_INDEX_LENGTH_; block < indexLength; 
               block += SURROGATE_BLOCK_COUNT_) {
              if(equal_int(index, block, otherBlock, SURROGATE_BLOCK_COUNT_)) {
                  return block;
              }
          }
          return indexLength;
      }
docs: Finds the same index block as the otherBlock
  @param index array
  @param indexLength size of index
  @param otherBlock
  @return same index block