Jean-Pierre Flori on Thu, 14 Jan 2016 13:23:15 +0100

 Re: Faster exponentiation in some extensions of finite fields of small characteristics

It seems it was an old buggy version of the patch.
I'm trying to relocate the right commit.

2016-01-14 11:58 GMT+01:00 Jean-Pierre Flori <jpflori@gmail.com>:
> Dear all,
>
> Here is a preliminary patch to speed up exponentiation in some
> extensions of finite fields of small characteristics (< size of
> machine word/2).
>
> It packs more coefficients of the polynomial representation over the
> prime field into machine words when the finite field element is mapped
> to a multiprecision integer (i.e. KS).
> * one function which packs 4 coeffs into a machine word,
> * one generic funciton which packs the coeffs as much as possible
> possibly crossing machine words boundaries.
>
> I did not take care of adding new tuning parameters or smartly
> choosing between the different functions, e.g. calling the
> 4-coeffs-in-1-word function when the (product) coeff size is
> BITS_IN_LONG/4-\epsilon might be more efficient than using the generic
> function which does more complicated packing when the polynomial
> degree is not large.
>
> I did not add (yet) optimal packing when the product coeffs are larger
> than a machine word.
>
> I did not really check it is bug free.
>
> Best,
> --
> Jean-Pierre Flori

--
Jean-Pierre Flori