Luhn Mod N in Cache?

LuhnMCheckSum(input) public {
  Set input = $Piece(input, "#", 1)
  Set codePoints = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789/:"
  Set n = $Length(codePoints)

  Set sum = 0
  Set factor = 2
  Set len = $Length(input)  
  For i = len:-1:1 {
    Set codePoint = $Find(codePoints, $Extract(input, i)) - 2
    Set addend = factor * codePoint
    Set factor = $Case(factor, 2: 1, : 2)
    Set addend = (addend \ n) + (addend # n)
    Set sum = sum + addend
  }
  Set remainder = sum # n
  Set checkCodePoint = (n - remainder) # n
  Return $Extract(codePoints, checkCodePoint + 1)
}
LuhnMValidate(input) public {
  Set checksum = $Piece(input, "#", 2)
  Set input = $Piece(input, "#")
  Return $$LuhnMCheckSum(input) = checksum
}