code: public int getIndexFromOffset(int offset)
     {
        int result = -1;
  
        for (int loop = 0; loop < m_offset.length; loop++)
        {
           if (m_offset[loop] == offset)
           {
              result = loop;
              break;
           }
        }
  
        return (result);
     }
docs: This method converts an offset value into an array index, which in
  turn allows the data present in the fixed block to be retrieved. Note
  that if the requested offset is not found, then this method returns -1.
  
  @param offset Offset of the data in the fixed block
  @return Index of data item within the fixed data block