Class: BWA::Message

Inherits:
Object
  • Object
show all
Defined in:
lib/bwa/message.rb

Defined Under Namespace

Classes: Unrecognized

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Message

Returns a new instance of Message.



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# File 'lib/bwa/message.rb', line 116

def initialize
  # most messages we're sending come from this address
  @src = 0x0a
end

Instance Attribute Details

#raw_data ⇒ Object (readonly)

Returns the value of attribute raw_data.



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# File 'lib/bwa/message.rb', line 114

def raw_data
  @raw_data
end

#src ⇒ Object

Returns the value of attribute src.



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# File 'lib/bwa/message.rb', line 17

def src
  @src
end

Class Method Details

.format_duration(minutes) ⇒ Object 



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# File 'lib/bwa/message.rb', line 109

def format_duration(minutes)
  format("%d:%02d", minutes / 60, minutes % 60)
end

.format_time(hour, minute, twenty_four_hour_time: true) ⇒ Object 



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# File 'lib/bwa/message.rb', line 99

def format_time(hour, minute, twenty_four_hour_time: true)
  if twenty_four_hour_time
    format("%02d:%02d", hour, minute)
  else
    print_hour = hour % 12
    print_hour = 12 if print_hour.zero?
    format("%d:%02d%s", print_hour, minute, (hour >= 12) ? "PM" : "AM")
  end
end

.inherited(klass) ⇒ Object 



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# File 'lib/bwa/message.rb', line 23

def inherited(klass)
  super

  @messages ||= []
  @messages << klass
end

.parse(data) ⇒ Object 



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# File 'lib/bwa/message.rb', line 30

def parse(data)
  offset = -1
  message_type = length = nil
  loop do
    offset += 1
    # Not enough data for a full message; return and hope for more
    return nil if data.length - offset < 5

    # Keep scanning until message start char
    next unless data[offset] == "~"

    # Read length (safe since we have at least 5 chars)
    length = data[offset + 1].ord

    # No message is this short or this long; keep scanning
    next if (length < 5) || (length >= "~".ord)

    # don't have enough data for what this message wants;
    # return and hope for more (yes this might cause a
    # delay, but the protocol is very chatty so it won't
    # be long)
    return nil if length + 2 > data.length - offset

    # Not properly terminated; keep scanning
    next unless data[offset + length + 1] == "~"

    # Not a valid checksum; keep scanning
    next unless CRC.checksum(data.slice(offset + 1, length - 1)) == data[offset + length].ord

    # Got a valid message!
    break
  end

  message_type = data.slice(offset + 3, 2)
  BWA.logger.debug "discarding invalid data prior to message #{BWA.raw2str(data[0...offset])}" unless offset.zero?

  src = data[offset + 2].ord
  klass = @messages.find { |k| message_type == k::MESSAGE_TYPE }

  if klass
    valid_length = if klass::MESSAGE_LENGTH.respond_to?(:include?)
                     klass::MESSAGE_LENGTH.include?(length - 5)
                   else
                     length - 5 == klass::MESSAGE_LENGTH
                   end
    unless valid_length
      BWA.logger.debug " read: #{BWA.raw2str(data.slice(offset, length + 2))}"

      raise InvalidMessage.new("Unrecognized data length (#{length}) for message #{klass}",
                               data)
    end
  else
    BWA.logger.info(
      "Unrecognized message type #{BWA.raw2str(message_type)}: #{BWA.raw2str(data.slice(offset, length + 2))}"
    )
    klass = Unrecognized
  end

  message = klass.new
  message.parse(data.slice(offset + 5, length - 5))
  message.instance_variable_set(:@raw_data, data.slice(offset, length + 2))
  message.instance_variable_set(:@src, src)
  if message.log?
    BWA.logger.debug " read: #{BWA.raw2str(data.slice(offset, length + 2))}"
    BWA.logger.info "from spa: #{message.inspect}"
  end
  [message, offset + length + 2]
end

Instance Method Details

#inspect ⇒ Object 



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# File 'lib/bwa/message.rb', line 134

def inspect
  "#<#{self.class.name} #{raw_data.unpack1("H*")}>"
end

#log? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/bwa/message.rb', line 121

def log?
  true
end

#parse(_data) ⇒ Object 



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# File 'lib/bwa/message.rb', line 125

def parse(_data); end

#serialize(message = "") ⇒ Object 



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# File 'lib/bwa/message.rb', line 127

def serialize(message = "")
  length = message.length + 5
  full_message = "#{length.chr}#{src.chr}#{self.class::MESSAGE_TYPE}#{message}"
  checksum = CRC.checksum(full_message)
  "\x7e#{full_message}#{checksum.chr}\x7e".b
end