tg at gmplib.org
Mon Feb 28 23:07:31 CET 2011
nisse at lysator.liu.se (Niels Möller) writes:
What are the current plans for retiring the divrem_1 interface? IIRC, we
agreed there should be an interface more or less like
div_qr_1 (mp_ptr qp, mp_limb_t *qh, mp_srcptr up, mp_size_t un,
and then preinv versions and separate functions for generating fraction
It would be easier to commit my new div_qr_1 code after this interface
change (if it's going to happen, that is).
I suppose it got stuck in the great complexity emerging from all our
ideas in the area.
I have lots of code, including assembly code, implementing the new
preliminary division interface. But your new 'pi1-b' precomputation
will need to be put between the pi1 and pi2 routines.
And then we have the issue of unnormalized divisors (it looks like
mpn_sbpi1_div_qr still requires that dp[dn-1] has the high bit set. I'm
afraid that's going to be a bit of work. I think the strategy should be
to normalize high limbs (the inputs to the 3/2 division) on the fly,
We surely need to compute the needed inverse from normalised operands.
Perhaps one could actually apply 3/2 division w/o normalising the 3 + 2
limbs, at the expense of more quotient limb overesimates?
then do the book-keping needed when doing the mpn_submul_1 calls with
I don't get this part.
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