ascii() for utf8

Does Postgresql have a function like ascii() that will
return the unicode codepoint value for a utf8 character?
(And symmetrically same for question chr() of course).

I didn't find anything in the docs so I think the answer
is no which leads me to ask... Why not? (Hard to believe
lack of need without concluding that either ascii() is
not needed, of utf8 text is little used.)

Are there technical problems in implementing such a
function? Has anyone else already done this (ie, is
there somewhere I could get it from?)

Is there some other non-obvious way to get the cp value
for the utf8 character?

I think I could use plperl or plpython for this but
this seems like an awful lot of overhead for such a
basic task.