Re: [avr-libc-dev] Test results

[Joerg Wunsch]

As Dmitry K. wrote:

> My desktop (Glibc) documents isinf() that return -1/0/+1
> and links to BSD 4.3 compatibility.  The date of man page
> is 1993.

OK, the FreeBSD man page says this:

HISTORY
  The fpclassify(), isfinite(), isinf(), isnan(), and isnormal()
  macros were added in FreeBSD 5.1.  3BSD introduced isinf() and
  isnan() functions, which accepted double arguments; these have
  been superseded by the macros described above.

So the major difference is that the C99 macros are supposed to take
either a float or double, but in turn, the standard only required them
to return nonzero.  The C99 rationale doesn't explain it, but I guess
this more liberal definition was used to allow an implementation that
could e.g. also return something like 0x80 in case it appears easier
to obtain that value.

-- 
cheers, J"org               .-.-.   --... ...--   -.. .  DL8DTL

http://www.sax.de/~joerg/                        NIC: JW11-RIPE
Never trust an operating system you don't have sources for. ;-)