xforms and php

[eCubeH]

Can anyone advise on how to configure PHP so as to be able to
(a) parse embedded php code in .xhtml files (application/xhtml+xml), as well as
(b) pure .php files (as text/html, without placing xml declarations etc).

I am able to run xforms in .xhtml files (using ff extension).
Separately I can run php code in .php files using the default php.ini mimetype of text/html.
But I am unable to get what I want as listed above.