global function utf8_to_ascii(sequence s)
-- created from Tommy's Unicode Library 1.2
-- copyright (c) 2003-2004 Tommy Carlier
  integer i, char, byte, bytes
  sequence res

  i = 1
  res = ""
  while i < length(s) do
    byte = s[i]
    char = 0
    if and_bits(byte,#80) = 0 then bytes = 1
    elsif and_bits(byte,#20) = 0 then bytes = 2
    elsif and_bits(byte,#10) = 0 then bytes = 3
    elsif and_bits(byte,#8) = 0 then bytes = 4
    elsif and_bits(byte,#4) = 0 then bytes = 5
    elsif and_bits(byte,#2) = 0 then bytes = 6
    else return "Incorrect UTF-8 char"
    end if
    byte = and_bits(byte, power(2, 8 - bytes) - 1)
    char += byte * power(64, bytes - 1)
    for n=1 to bytes-1 do
      i += 1
      byte = s[i]
      if byte=0 then
        return "Unexpected end of UTF-8 string"
      elsif byte<0 then
        return "Incorrect UTF-8 char"
      end if
	  byte = and_bits(byte,63)
      char += byte * power(64,bytes-1-n)
    end for
    res &= char
    i += 1
  end while
  return res
end function