Doxygen certainly documents straight C functions.
After more testing
Use the Doxywizard and check the values in expert mode - it provides some nice help when you mouse over things. In particular, you should have changed the default so EXTRACT_ALL is
checked
I think needing this to be set, opposite to the default, is possibly a bug.
If desperate, post the settings up in the question. I just created a sample from scratch and verified that your function showed up using Doxygen when I use EXTRACT_ALL but there is no File Members section if I turn that off.
You should see the functions underneath Files - File Members, as seen here in the VTK docs.
Sorry I didn't pick it up earlier but I always have EXTRACT_ALL on as I'm working on legacy code bases where most functions lack special comments.
earlier idea Try adding an @file comment at the top of the file to see if that is being processed.
/// @file fred.h This file defines functions used in fred.m
My bet is that your file extension or your directory is not included in the doxygen setup file you're running.