Earlier quoted context omitted.
It's a hardcoded map of int to string. That's a fairly reasonable way of doing it in vanilla C. How efficient it actually is is down to your compiler. And some compilers impose maximum limits on the size of `case` statements.. An alternative would be a precomputed hash table, similar to what `gperf` does. Requires more work in the build system though.
Besides the curious length of the switch, I'm not seeing anything particularly 'bad' about this code .. sort of left wondering what the big deal is? This is perfectly reasonable code.
It doesn't look too terrible, but it looks like it is optimized for speed, not maintainability. I'm assuming that's why there is a lot of repeated code (instead of putting it into a function/loop). The comments are a little spartan.