Quick decode of coap option number

coap-option.rb

#!/usr/bin/env ruby -KU

ARGV.each do |arg|
  i = Integer(arg)
  puts "Option number: #{i} = 0b#{"%b" % i} = 0x#{"%x" % i}"

  no_cache_key = false
  descr = " "

  descr << " C = #{i[0]}"
  if i[0] != 0
    puts "  Critical"
  else
    puts "  Elective"
  end
  descr << ", U = #{i[1]}"
  if i[1] != 0
    puts "  Unsafe-to-forward"
  else
    descr << ", N = #{"%03b" % i[2..4]}"
    puts "  Safe-to-forward"
    if i[2..4] == 7
      puts "  No Cache Key"
      no_cache_key = true
    end
  end
  unless no_cache_key
    puts "  Cache Key"
  end
  puts descr
end