can't convert mixed encode file

[ifq]

I have lots of C source file, which mixed with GB2312 and UTF-8 comments.
I want to convert all GB2312 to utf8, and enca

$ enconv -d io.c
io.c: Unrecognized encoding
  Failure reason: No clear winner.

If I manually delete utf8 encoded comment in io.c file, then the process goes well.

Is it possible to add an option, like -i utf-8 , which keep specific encoded part in file, and convert other part of the file.

I searched a lot today, seems like no tools support this kind of function.

[nijel]

There is no such feature right now, sorry.