Method readPacket

plugins/e57/libE57Format/src/Packet.cpp:159–233

}

void PacketReadCache::readPacket( unsigned oldestEntry, uint64_t packetLogicalOffset )
{
#ifdef E57_VERBOSE
   std::cout << "PacketReadCache::readPacket() called, oldestEntry=" << oldestEntry
             << " packetLogicalOffset=" << packetLogicalOffset << std::endl;
#endif

   // Read header of packet first to get length.  Use EmptyPacketHeader since  it has the fields
   // common to all packets.
   EmptyPacketHeader header;

   cFile_->seek( packetLogicalOffset, CheckedFile::Logical );
   cFile_->read( reinterpret_cast<char *>( &header ), sizeof( header ) );

   // Can't verify packet header here, because it is not really an EmptyPacketHeader.
   unsigned packetLength = header.packetLogicalLengthMinus1 + 1;

   // Be paranoid about packetLength before read
   if ( packetLength > DATA_PACKET_MAX )
   {
      throw E57_EXCEPTION2( ErrorBadCVPacket, "packetLength=" + toString( packetLength ) );
   }

   auto &entry = entries_.at( oldestEntry );

   // Now read in whole packet into preallocated buffer_.  Note buffer is
   cFile_->seek( packetLogicalOffset, CheckedFile::Logical );
   cFile_->read( entry.buffer_, packetLength );

   // Verify that packet is good.
   switch ( header.packetType )
   {
      case DATA_PACKET:
      {
         auto dpkt = reinterpret_cast<DataPacket *>( entry.buffer_ );

         dpkt->verify( packetLength );
#ifdef E57_VERBOSE
         std::cout << "  data packet:" << std::endl;
         dpkt->dump( 4 ); //???
#endif
      }
      break;
      case INDEX_PACKET:
      {
         auto ipkt = reinterpret_cast<IndexPacket *>( entry.buffer_ );

         ipkt->verify( packetLength );
#ifdef E57_VERBOSE
         std::cout << "  index packet:" << std::endl;
         ipkt->dump( 4 ); //???
#endif
      }
      break;
      case EMPTY_PACKET:
      {
         auto hp = reinterpret_cast<EmptyPacketHeader *>( entry.buffer_ );