- addlog(...) is identical to log(-1, ...). Get rid of it to avoid

- addlog(...) is identical to log(-1, ...). Get rid of it to avoid
  duplicate code and change sppp(4) to use log(-1, ...).

- Add support for the 'j' and 't' size modifiers.

- Add support for the 'i' (alias for 'd'), 'n' and 'X' conversions. Use
  uintmax_t in ksprintn() and get rid of ksprintqn(). Do some structural
  cleanup in kvcprintf().

- Make 'z' modifier always print values as signed.

- Change a return to a break to properly free the local buffers.

- When padding with zero, do pad after prefixes rather than before.

- Perform some style(9) cleanup.

Taken-from (with some adjustments): FreeBSD