-- calculate CRC-32 checksum
str = "The quick brown fox jumps over the lazy dog"

-- is shared library (in Director called "Xtra", a DLL in windows, a sharedLib in
-- OS X) available?
if ilk(xtra("Crypto"))=#xtra then

  -- use shared library
  cx = xtra("Crypto").new()
  crc = cx.cx_crc32_string(str)

else

  -- otherwise use (slower) pure lingo solution
  crcObj = script("CRC").new()
  crc = crcObj.crc32(str)

end if