I can't judge the content of the patch because I don't know these
formats at all, however there are a few issues about the style:
1) there are tabs mixed with spaces, the standard is 4 spaces;
2) there should be an empty space before and after operators like ==, <
and >;
3) h and f are not really meaningful names, I can't figure out what they
are supposed to represent.
For further information about the style conventions see
http://www.python.org/dev/peps/pep-0008/

The "import struct" might be better at module level; 'f' is passed to
both the function and never used; the docstrings may be more comprehensive.

Finally, it would be nice if you could provide a patch against the
trunk, you can find more information about it on
http://www.python.org/dev/patches/ and
http://www.python.org/dev/faq/#patches

If you have any question feel free to ask.