prefix

# File lib/ipaddr.rb, line 427
  def prefix
    case @family
    when Socket::AF_INET
      n = IN4MASK ^ @mask_addr
      i = 32
    when Socket::AF_INET6
      n = IN6MASK ^ @mask_addr
      i = 128
    else
      raise AddressFamilyError, "unsupported address family"
    end
    while n.positive?
      n >>= 1
      i -= 1
    end
    i
  end