French RIO Checksum and Check procedure

rio.coffee

#
# Used to calculate the checksum
# http://fr.wikipedia.org/wiki/Relev%C3%A9_d'identit%C3%A9_op%C3%A9rateur
#
exports.calcChksm = (oo, q, rrrrrr, notel) ->
  concatenation = "#{oo}#{q}#{rrrrrr}#{notel}"
  ordre = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789+"
  a = b = c = 0

  for i in concatenation
    p = ordre.indexOf i
    a = (1 * a + p ) % 37
    b = (2 * b + p ) % 37
    c = (4 * c + p ) % 37

  ccc = "#{ordre[a]}#{ordre[b]}#{ordre[c]}"
  return ccc

#
# Used to check if a RIO, match the phone number
#
exports.checkRIO = (rio, notel) ->
  throw Error("RIO is mandatory !") if rio == null
  throw Error("Invalid RIO Length !") if rio.length != 12
  throw Error("Tel Number is mandatory !") if notel == null
  throw Error("Invalid Tel Number Length !") if notel.length != 10

  chk = exports.calcChksm(rio[0..1], rio[2], rio[3..8], notel)
  if rio[9..11] == chk
    return true
  else
    throw Error("Invalid RIO")