Class: Seriamp::Backend::FFIBackend::Device

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/seriamp/backend/ffi.rb

Defined Under Namespace

Modules: C Classes: IntPtr

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(device, logger: nil) ⇒ Device

Returns a new instance of Device.



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# File 'lib/seriamp/backend/ffi.rb', line 13

def initialize(device, logger: nil)
  @logger = logger

  if @f
    yield
  else
    logger&.debug("Opening device #{device}")
    File.open(device, 'r+') do |f|
      unless f.isatty
        raise BadDevice, "#{device} is not a TTY"
      end
      @f = f
      set_rts

      if IO.select([f], nil, nil, 0)
        logger&.warn("Serial device readable without having been written to - concurrent access?")
      end

      tries = 0
      begin
        do_status
      rescue Timeout::Error
        tries += 1
        if tries < 5
          logger&.warn("Timeout handshaking with the receiver - will retry")
          retry
        else
          raise
        end
      end
      yield.tap do
        @f = nil
      end
    end
  end
rescue IOError => e
  if @f
    logger&.warn("#{e.class}: #{e} while operating, closing the device")
    @f.close
    raise
  end
end

Instance Attribute Details

#logger ⇒ Object (readonly)

Returns the value of attribute logger.



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# File 'lib/seriamp/backend/ffi.rb', line 56

def logger
  @logger
end

Instance Method Details

#set_rts ⇒ Object 



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# File 'lib/seriamp/backend/ffi.rb', line 59

def set_rts
  ptr = IntPtr.new
  C.ioctl_p(@f.fileno, TIOCMGET, ptr)
  if logger&.level <= Logger::DEBUG
    flags = []
    %w(DTR RTS CTS).each do |bit|
      if ptr[:value] & self.class.const_get("TIOCM_#{bit}") > 0
        flags << bit
      end
    end
    if flags.empty?
      flags = ['(none)']
    end
    logger&.debug("Initial flags: #{flags.join(' ')}")
  end
  unless ptr[:value] & TIOCM_RTS
    logger&.debug("Setting RTS on #{device}")
    ptr[:value] |= TIOCM_RTS
    C.ioctl_p(@f.fileno, TIOCMSET, ptr)
  end
end