code: public long readLong(final int index) {
          long l1 = readInt(index);
          long l0 = readInt(index + 4) & 0xFFFFFFFFL;
          return (l1 << 32) | l0;
      }
docs: Reads a signed long value in {@link #b b}. <i>This method is intended for
  {@link Attribute} sub classes, and is normally not needed by class
  generators or adapters.</i>
  
  @param index the start index of the value to be read in {@link #b b}.
  @return the read value.