Simple Ruby program that uses serialport gem to connect with a serial-attached device

threaded_terminal.rb

require 'serialport'
require 'highline/import'

class HighLine 
  public :get_character
end

class ThreadedTerminal
  class << self
    MODEM = '/dev/tty.usbmodem0000001'
    
    def start
      @sp = SerialPort.new(MODEM)
      @sp.read_timeout = 500
      
      @output = []
      @alive = true
            
      receiver_thread = Thread.new do
        while @alive do
          data = @sp.getc
          if not data.nil?
            @output << data
          end
        end
      end
      
      writer_thread = Thread.new do
        input = HighLine.new 
        while @alive do
          while (c = input.get_character) != ?\e do
            if not c.nil?
              @output << c.chr
            end
            @sp.write(c.chr)
          end
        end
      end
      
      display_thread = Thread.new do
        while @alive do
          @output.each do |character|
            print "#{character}"
            @output = @output.drop(1)
          end
        end
      end
      
      [display_thread, receiver_thread, writer_thread].each(&:join)
      
      @sp.close
    end
    
  end
end

ThreadedTerminal.start