code: public static double decodeDoubleDesc(byte[] src, int srcOffset)
          throws CorruptEncodingException
      {
          long bits = DataDecoder.decodeDoubleBits(src, srcOffset);
          if (bits >= 0) {
              bits ^= 0x7fffffffffffffffL;
          }
          return Double.longBitsToDouble(bits);
      }
docs: Decodes a double from exactly 8 bytes, as encoded for descending order.
  
  @param src source of encoded bytes
  @param srcOffset offset into source array
  @return double value