Module: Px4LogReader::LogFile

Defined in:
lib/px4_log_reader/log_file.rb

Constant Summary collapse

HEADER_MARKER = 
[0xA3,0x95]
HEADER_LENGTH = 
3
FORMAT_DESCRIPTOR_TABLE = 
{ FORMAT_MESSAGE.type => FORMAT_MESSAGE }.freeze

Class Method Summary collapse

Class Method Details

.read_descriptor(buffered_io, skip_corrupt = true) ⇒ Object 



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# File 'lib/px4_log_reader/log_file.rb', line 59

def self.read_descriptor( buffered_io, skip_corrupt=true )

  message_descriptor = nil

  begin

    descriptor_message = read_message( buffered_io, FORMAT_DESCRIPTOR_TABLE )

    if descriptor_message

      message_descriptor = Px4LogReader::MessageDescriptor.new
      message_descriptor.from_message( descriptor_message )

    end

  rescue Px4LogReader::InvalidDescriptorError => error

    if skip_corrupt
      retry
    else
      raise error
    end

  rescue StandardError => e
    puts "#{e.class}: #{e.message}"
    puts e.backtrace.join("\n")
  end

  return message_descriptor
end

.read_descriptors(buffered_io, descriptor_cache = nil) ⇒ Object 



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# File 'lib/px4_log_reader/log_file.rb', line 41

def self.read_descriptors( buffered_io, descriptor_cache=nil )

  message_descriptors = {}

  while ( message_descriptor = read_descriptor( buffered_io ) ) do
    if !message_descriptors.keys.include? message_descriptor.type
      message_descriptors[ message_descriptor.type ] = message_descriptor
    end
  end

  # If a cache filename was supplied, dump the descriptors to the cache
  if descriptor_cache
    descriptor_cache.write_descriptors( message_descriptors )
  end

  return message_descriptors
end

.read_message(buffered_io, message_descriptors) ⇒ Object 



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# File 'lib/px4_log_reader/log_file.rb', line 90

def self.read_message( buffered_io, message_descriptors )

  message = nil
  while message.nil? do
    message_type = read_message_header( buffered_io )

    if message_type

      message_descriptor = message_descriptors[ message_type ]

      if message_descriptor
        message_data = buffered_io.read( message_descriptor.length - HEADER_LENGTH )
        message = message_descriptor.unpack_message( message_data )
      end

    elsif message_type.nil?
      break
    end
  end

  return message
end

.read_message_header(buffered_io) ⇒ Object 



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# File 'lib/px4_log_reader/log_file.rb', line 113

def self.read_message_header( buffered_io )
  message_type = nil

  begin

    data = buffered_io.read(2)

    if data && data.length == 2

      while !data.empty? && message_type.nil? do

        if ( byte = buffered_io.read(1) )
          data << byte
        end

        if data.unpack('CCC')[0,2] == HEADER_MARKER
          message_type = data.unpack('CCC').last & 0xFF
        else
          data = data[1..-1]
        end

      end
    end

  rescue EOFError => error
    # Nothing to do.
  rescue StandardError => error
    puts error.message
    puts error.backtrace.join("\n")
  end

  return message_type
end

.write_message(io, message) ⇒ Object 



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# File 'lib/px4_log_reader/log_file.rb', line 148

def self.write_message( io, message )
  io.write HEADER_MARKER.pack('CC')
  io.write [ message.descriptor.type ].pack('C')
  io.write message.pack
end