Class: Cosmos::LincHandshake

Inherits:
Object
  • Object
show all
Defined in:
lib/cosmos/interfaces/linc_interface.rb

Overview

The LincHandshake class is used only by the LincInterface. It processes the handshake and helps with finding the information regarding the internal command.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(handshake, interface_target_name) ⇒ LincHandshake

Returns a new instance of LincHandshake.



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# File 'lib/cosmos/interfaces/linc_interface.rb', line 287

def initialize(handshake, interface_target_name)
  @handshake = handshake

  # Interpret the command field of the handshake packet
  # Where DATA is defined as:
  # 1 byte target name length
  # X byte target name
  # 1 byte packet name length
  # X byte packet name
  # 4 byte packet data length
  # X byte packet data
  # 4 byte error source length
  # X byte error source
  data = handshake.read('DATA')
  raise "Data field too short for target name length" if data.length == 0

  # Get target name length
  target_name_length = data[0..0].unpack('C')[0]
  raise "Invalid target name length" if target_name_length == 0
  data = data[1..-1]

  # get target name
  raise "Data field too short for target name" if data.length < target_name_length
  # target_name = data[0..(target_name_length - 1)] # Unused
  data = data[target_name_length..-1]

  # get packet name length
  raise "Data field too short for packet name length" if data.length == 0
  packet_name_length = data[0..0].unpack('C')[0]
  raise "Invalid packet name length" if packet_name_length == 0
  data = data[1..-1]

  # get packet name
  raise "Data field too short for packet name" if data.length < packet_name_length
  packet_name = data[0..(packet_name_length - 1)]
  data = data[packet_name_length..-1]

  # get packet data length
  raise "Data field too short for packet data length" if data.length < 4
  packet_data_length = data[0..3].unpack('N')[0]
  raise "Invalid data length" if packet_data_length == 0
  data = data[4..-1]

  # get packet data
  raise "Data field too short for packet data" if data.length < packet_data_length
  packet_data = data[0..(packet_data_length - 1)]
  data = data[packet_data_length..-1]

  # get error source length
  raise "Data field too short for error source length" if data.length < 4
  error_source_length = data[0..3].unpack('N')[0]
  # note it is OK to have a 0 source length
  data = data[4..-1]

  # get error source - store on object
  if error_source_length > 0
    @error_source = data[0..(error_source_length - 1)]
  else
    @error_source = ''
  end

  # make packet - store on object as a defined packet of type command that this handshakes
  @identified_command = System.commands.packet(interface_target_name, packet_name).clone
  @identified_command.buffer = packet_data
  @identified_command.received_time = Time.at(handshake.read('TIME_SECONDS'), handshake.read('TIME_MICROSECONDS'))
end

Instance Attribute Details

#error_source ⇒ Object

Returns the value of attribute error_source.



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# File 'lib/cosmos/interfaces/linc_interface.rb', line 285

def error_source
  @error_source
end

#handshake ⇒ Object

Returns the value of attribute handshake.



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# File 'lib/cosmos/interfaces/linc_interface.rb', line 283

def handshake
  @handshake
end

#identified_command ⇒ Object

Returns the value of attribute identified_command.



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# File 'lib/cosmos/interfaces/linc_interface.rb', line 284

def identified_command
  @identified_command
end

Instance Method Details

#get_cmd_guid(fieldname_guid) ⇒ Object 



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# File 'lib/cosmos/interfaces/linc_interface.rb', line 354

def get_cmd_guid(fieldname_guid)
  return @identified_command.read(fieldname_guid)
end