Cofactor canonicalisation of mpn_gcdext
tg at gmplib.org
Wed May 4 17:01:09 CEST 2011
nisse at lysator.liu.se (Niels Möller) writes:
I'm about to check in the attached mpz/gcdext.c. It does two things,
both related to the tmp allocations.
1. In the common case, allocates space corresponding to the smaller
input (called vn in earlier mail, and bsize in this code), rather
2. In the uncommon case V == 0,, construct the return values without any
tmp allocations at all. I don't think this case is very important to
optimize, but since G = U in this case, the correct G doesn't fit in
tmp_gp as allocated for the common case, and hence it makes sense to
me to handle it specially.
Passes make check. But maybe I should wait until the testing system
builds the main gmp tree?
Should wait to do what?
If you are confident about the patch why not just check it in?
As for the documentation, I'll change the compatibility note to say
that the older versions required un+1 allocation (rather then the
smaller vn+1)? That was the documented requirement, I don't think it
makes any sense, but maybe the old code really overwrites un - vn limbs
that will never hold any real data. I don't really feel like doing a
more thorough investigation of the behaviour of ancient versions.
Let's be conservative then.
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