Getting Locale from User Agent

Hello Is there an easy way to get the locale as an iso lang dialect notation from the client? I know that I can parse the HTTP_ACCEPT_LANGUAGE in $_SERVER and try to form one from it but I would like to have something like getLocale and it will return 'en_EN' or 'de_DE' (etc...) setlocale isn't quite what I'm looking for since it returns language country as names e.g. German Germany (at least on my platform) and as far as I understand it it can only be used to obtain the locale of the server. So is there any build in function that can return a locale for the useragent? Thanks in advance Stefan Langer