tg at gmplib.org
Sun May 2 08:11:30 UTC 2021
IIRC, Svoboda's division trick for N/D is to find a small multiplier m
such that, for the division mN/(mD) we have mD = 100000...XX... with the
high limb of mD being 1000...0.
This idea works also for 2-adic division. Find m = D^(-1) mod \beta
where \beta is the lomb base. Then do mN/(mD) or mN mod (mD) with
2-adic norm. Now mD will end in 0...0001, and the quotient limbs will
be the low limbs of the intermediate remainder.
That should mean that we could use mul_basecase directly for
sbpi1_bdiv_r (or its sibling redc_1).
Surely this is not a new observation.
Please encrypt, key id 0xC8601622
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