mpi/ec: small optimization for ec_mulm_448

* mpi/ec.c (ec_addm_448, ec_subm_448): Change order of sub_n and
set_cond to remove need to clear 'n'.
(ec_mulm_448): Use memcpy where possible; Use mpih_rshift where
possible; Use mpih_lshift for doubling a3; Remove one addition
at end.
--

Benchmarks on AMD Ryzen 7 5800X:

Before:
 Ed448          |  nanosecs/iter   cycles/iter  auto Mhz
         keygen |         893096       4343326      4863
           sign |         988422       4795694      4852
         verify |        1899706       9215952      4851

After (~5% faster):
 Ed448          |  nanosecs/iter   cycles/iter  auto Mhz
         keygen |         822078       3987952      4851
           sign |         947327       4595433      4851
         verify |        1776259       8616675      4851

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>

0 files changed, 0 insertions, 0 deletions