mpz_limbs interface

Niels Möller nisse at
Thu Feb 6 13:08:03 UTC 2014

Marc Glisse <marc.glisse at> writes:

> On Thu, 6 Feb 2014, Niels Möller wrote:
>> I'm looking at the definition of DOUBLE_NAN_INF_ACTION in gmp-impl.h.
>> Maybe it could be simplified to a single, unconditional, definition
> Note that there exist standard functions like isfinite.

But so far, we don't use any libm functions in gmp. 

>>  * no slower then the _GMP_IEEE_FLOATS definition (which extracts the
>>    exponent via a union).
> Are you sure about that?

I'm not sure about anything... I'd expect that moving floating point
values to integer registers (or to memory) is often slow.

> If x is a denormal, x-x may take a very long
> time to compute.

I don't think the case of denormals is very important for performance.
And there's a bit-by-bit normalization loop for that case later on. How
long is "very long"? 10 cycles? 100 cycles?

>> Ok? Or should this wait until after 5.2?
> I would have been in favor of avoiding new features less than a couple
> months before the release, but since there are already plenty of *sec*
> changes going on...

Personally, I feel a bit easier about adding feature close to release,
than about rewriting code for existing features.


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