instance method get_order

# File actionmailer/lib/action_mailer/vendor/tmail-1.2.7/tmail/vendor/rchardet-1.3/lib/rchardet/chardistribution.rb, line 197
    def get_order(aStr)
      # for sjis encoding, we are interested 
      #   first  byte range: 0x81 -- 0x9f , 0xe0 -- 0xfe
      #   second byte range: 0x40 -- 0x7e,  0x81 -- oxfe
      # no validation needed here. State machine has done that
      aStr = aStr[0..1].join if aStr.class == Array
      if (aStr[0..0] >= "\x81") and (aStr[0..0] <= "\x9F")
        order = 188 * (aStr[0] - 0x81)
      elsif (aStr[0..0] >= "\xE0") and (aStr[0..0] <= "\xEF")
        order = 188 * (aStr[0] - 0xE0 + 31)
      else
        return -1
      end
      order = order + aStr[1] - 0x40
      if aStr[1..1] > "\x7F"
        order =- 1
      end
      return order
    end