Convert UTF-8 to PHP defines

We use PHP defines for defining text in different languages. As far as I know PHP files are supposed to be ASCII, not UTF-8 or something like that. What I want to make is a conversion program that would convert a given UTF-8 file with the format definetext1=this is a text in random UTF-8, probably arabic or similar text definetext2=this is another text in random UTF-8, probably arabic or similar text into a file with the following defines define('definetext1',chr(<t_value>).chr(<h_value>).chr(<i_value>)...<chr(<x_value>).chr(<t_value>)); define('definetext2,chr(<t_value>).chr(<h_value>).chr(<i_value>)...<chr(<x_value>).chr(<t_value>)); Not sure if I'm using the correct chr/ord function, but I hope the above is clear enough to make clear what I'm looking for. Basically the output file should be ascii and not contain any utf-8. Any advise? The html_special_chars did not seem to work for Vietnamese text I tried to convert, so something seems to get wrong with just reading an array of strings and converting the strings and putting them in defines.