sscanf and sprintf

Unless some earlier header file has left a pragma (or similar) that packs structures active there should be two bytes of padding between 'Var1' and 'Sub'.

It might be that the printf/scanf implementations aren't processing %hh properly, and that the cut-down versions don't support field widths properly either, also %i isn't standard, use %d.

I would use 'unsigned char' on the printf() to avoid the need for %hh.

IIRC Altera's printf() brings in about 70k of code, it is possible to write an snprintf() that is much, much smaller and a lot faster.

In any case code like:

    static const char hex = "0123456789abcdef";
    buf = hex;
    buf = hex;
    buf = hex;
    ...

will be much faster.