cdb wrote:
> However this does not work
>
> *fnt = *fnt ^ 0xFF;

How about:

  *fnt = (*fnt) ^ 0xFF;

I'm no C whiz, but leaving things up to the compiler precedence rules when
it's not really obvious +, -, *, and / stuff can lead to unexpected
problems.  Even if you are a C whiz and know for sure how precedence will be
applied here, it doesn't hurt to make it clear for others reading the code.

To some extent you should assume readers of your code know the language, and
documenting that instead of the intent is a waste of space and takes
displaces from useful documentation.  On the other hand, obscure details or
common misconceptions are worth documenting.  I'm not enough of a C user to
know how obvious the * versus ^ precedence is to most people, but I would
have to look it up if I needed to know.

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