Method ReadRangeData

lib/mdflib/mdflib/src/dg4block.cpp:344–446

}

void Dg4Block::ReadRangeData(std::streambuf& buffer, DgRange& range) {
  const auto& block_list = DataBlockList();
  if (block_list.empty()) {
    return;
  }

  InitFastObserverList();

  // First scan through all CN blocks and set up any VLSD CG or MLSD channel
  // relations.
  for (const auto& cg4 : cg_list_) {
    if (!cg4) {
      continue;
    }
    const uint64_t record_id = cg4->RecordId();
    const bool cg_used = range.IsUsed(record_id);
    // Do not read SD or SD data if the channel group isn't requested.
    if (!cg_used) {
      continue;
    }
    // Fetch all data from sample reduction blocks (SR), but only if the
    // channel group data is subscribed.
    for (const auto& sr4 : cg4->Sr4()) {
      if (!sr4) {
        continue;
      }
      sr4->ReadData(buffer);
    }

    // Fetch all signal data (SD)
    const auto channel_list = cg4->Channels();
    for (const auto* channel :channel_list) {
      if (channel == nullptr) {
        continue;
      }
      // Check if the channel is in the subscription
      if (!IsSubscribingOnChannel(*channel) ) {
        continue;
      }
      const auto* cn_block = dynamic_cast<const Cn4Block*>(channel);
      if (cn_block == nullptr) {
        continue;
      }
      // Fetch the channels referenced data block. Note that some types of
      // data blocks are owned by this channel as an SD block, but some are only
      // references to block own by another block. Of interest is VLSD CG block
      // and MLSD channel.
      const auto data_link = cn_block->DataLink();
      if (data_link == 0) {
        continue; // No data to read into the system
      }
      const auto* block = Find(data_link);
      if (block == nullptr) {
        MDF_DEBUG() << "Missing data block in channel. Channel :"
                    << cn_block->Name()
                    << ", Data Link: " << data_link;

        continue; // Strange that the block doesn't exist