[PATCH v2] Force correct sign for intermediate steps of bigmulHEADmaster

Since y1 is usually smaller than y0, the sign of (x0 - x1) * (y1 - y0)
is usually the same as that of (x0 - x1). This isn't always the case,
though, especially if y is 2^Large * small.

Also, the result of umul should be trimmed, so that we can trust that
z0, z1 are trimmed in kmul. Otherwise, if their signs are different,
bigadd(z1, z0) may become confused about which has greater magnitude and
perform an incorrect subtraction. Since the result of kmul comes from
bigadd(), which trims already, we need only trim the result of smallmul
to ensure that umul's result is trimmed.

0 files changed, 0 insertions, 0 deletions