Method write_parameter_id

dds/DCPS/Serializer.cpp:556–612

}

bool Serializer::write_parameter_id(const unsigned id, const size_t size, const bool must_understand)
{
  if (static_cast<ACE_CDR::ULong>(id) > MEMBER_ID_MAX) {
    return false;
  }

  const Encoding::XcdrVersion xcdr = encoding().xcdr_version();
  if (xcdr == Encoding::XCDR_VERSION_1) {
    if (!align_w(xcdr1_pid_alignment)) {
      return false;
    }

    // Determine if we need to use a short or long PID
    const bool long_pid = id > (1 << 14) || size > (1 << 16);

    // Write the short part of the PID
    /*
     * TODO(iguessthislldo): Control when to use "must understand" and "impl
     * extension"?
     *
     * The XTypes CDR rules seem to imply they're alway here but that doesn't
     * sound quite right.
     *
     * Also see TODOs above and the TODO below.
     */
    const ACE_CDR::UShort pid_id =
      pid_impl_extension + pid_must_understand +
      (long_pid ? pid_extended : static_cast<ACE_CDR::UShort>(id));
    if (!(*this << pid_id)) {
      return false;
    }
    const ACE_CDR::UShort pid_size = long_pid ? 8 : ACE_CDR::UShort(size);
    if (!(*this << pid_size)) {
      return false;
    }

    // If PID is long, write the extended/long part.
    if (long_pid && (
          !(*this << static_cast<ACE_CDR::ULong>(id)) ||
          !(*this << static_cast<ACE_CDR::ULong>(size)))) {
      return false;
    }

    reset_alignment();
  } else if (xcdr == Encoding::XCDR_VERSION_2) {
    // Compute Length Code, write EM Header and NEXTINT
    const ACE_CDR::ULong lc = (size == 1 ? 0 : size == 2 ? 1 : size == 4 ? 2 : size == 8 ? 3 : 4);
    const ACE_CDR::ULong emheader = (lc << 28) | id | (must_understand ? emheader_must_understand : 0);
    if (!(*this << emheader)) {
      return false;
    }
    if (lc == 4) {
      return *this << ACE_CDR::ULong(size);
    }
  }
  return true;
}