I wonder what's the downside of just using a native format implementation like
the one in Vstr[1] or bstring[2]?
I'd suggest taking the kernel vsnprintf() instead. It has the standard
interface (no support for FP, but we don't care) so it should be pretty
easy to just plug in, and it doesn't reaquire much of the environment
(just a 64-bit divide&modulus-by-100000).
Linus