... returns string literals if appropriate, iterates over subsequent flag chars parsing them into bitflags via a small-int-map, checks if a digit's next & parses that as a width, checks if a "."'s next & parses the following digits as the precision or indicates it should be taken from variadic args, looks up the following datatype-char in a lookuptable, parses following chars according to bitflags, & handles any errors.
2/3?
This interpreter's mainloop branching over the result to either:
* Carefully `memcpy()` literals into place
* Possibly-reformats ints into the desired bitwidth before having a helper decode flags, possibly prepend a sign, uses micro-optimized code to output base-8/10*/16 numbers, enforces minimum precision, & assembles the padding, sign, base-prefix, preceding spaces/zeroes, digits, & trailing spaces.
...
3/4?
*Particularly tricky to micro-optimize, its not a power-of-2!
