public void headerobj_to_bytestream(byte[] buffer, int offset)
 {
     DEFSX.set_int(buffer, offset + 0, (int)optype);
     DEFSX.set_long(buffer, offset + 4, payload_size);
     DEFSX.set_int(buffer, offset + 8, driveid);
     DEFSX.set_long(buffer, offset + 12, driveoffset);
     DEFSX.set_int(buffer, offset + 20, datasize);
     DEFSX.set_long(buffer, offset + 24, seq_num);
 }