Method: OpenC3::Interface#read

Defined in:
lib/openc3/interfaces/interface.rb

#read ⇒ Packet

Retrieves the next packet from the interface.

Returns:

  • (Packet) —

    Packet constructed from the data. Packet will be unidentified (nil target and packet names)



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# File 'lib/openc3/interfaces/interface.rb', line 269

def read
  raise "Interface not connected for read: #{@name}" unless connected?
  raise "Interface not readable: #{@name}" unless read_allowed?

  first = true
  loop do
    # Protocols may have cached data for a packet, so initially just inject a blank string
    # Otherwise we can hold off outputting other packets where all the data has already
    # been received
    extra = nil
    if !first or @read_protocols.length <= 0
      # Read data for a packet
      data, extra = read_interface()
      unless data
        Logger.info("#{@name}: read_interface requested disconnect")
        return nil
      end
    else
      data = ''
      first = false
    end

    @read_protocols.each do |protocol|
      # Extra check is for backwards compatibility
      if extra
        data, extra = protocol.read_data(data, extra)
      else
        data, extra = protocol.read_data(data)
      end
      if data == :DISCONNECT
        Logger.info("#{@name}: Protocol #{protocol.class} read_data requested disconnect")
        return nil
      end
      break if data == :STOP
    end
    next if data == :STOP

    # Extra check is for backwards compatibility
    if extra
      packet = convert_data_to_packet(data, extra)
    else
      packet = convert_data_to_packet(data)
    end

    # Potentially modify packet
    @read_protocols.each do |protocol|
      packet = protocol.read_packet(packet)
      if packet == :DISCONNECT
        Logger.info("#{@name}: Protocol #{protocol.class} read_packet requested disconnect")
        return nil
      end
      break if packet == :STOP
    end
    next if packet == :STOP

    # Return packet
    @read_count += 1
    Logger.warn("#{@name}: Interface unexpectedly requested disconnect") unless packet
    return packet
  end
rescue Exception => e
  Logger.error("#{@name}: Error reading from interface")
  disconnect()
  raise e
end