On Mit, 2011-10-05 at 17:01 +1000, Peter Hutterer wrote:
> Co-authored by Jeremy Huddleston <[email protected]>
> Signed-off-by: Peter Hutterer <[email protected]>
[...]
> +FP3232
> +double_to_fp3232(double in)
> +{
> + FP3232 ret;
> + int32_t integral;
> + double tmp;
> + uint32_t frac_d;
> +
> + tmp = floor(in);
> + integral = (int32_t)tmp;
> + tmp = ldexp(in - (int)in, 32);
This needs to be
ldexp(in - integral, 32)
or it's incorrect for -x.y with y > 5.
Though I'm not sure what using ldexp() instead of (1ULL << 32) or (1 <<
16) buys in exchange for generating larger and probably less efficient
code. If you insist in using ldexp though, consider converting the above
to
(in - integral) * ldexp(1, 32)
which gcc seems clever enough to turn into the same code as
(in - integral) * (1ULL << 32)
In general, I find the conversion code so verbose as to be borderline
confusing, but I guess the top priority right now is to make it
correct...
I assume there will be followup patches to make the relevant code use
these and fix make check.
--
Earthling Michel Dänzer | http://www.amd.com
Libre software enthusiast | Debian, X and DRI developer
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