fe_limb_t
static void fe_mul_impl(fe_limb_t out[FE_NUM_LIMBS],
const fe_limb_t in1[FE_NUM_LIMBS],
const fe_limb_t in2[FE_NUM_LIMBS]) {
static void fe_cmov(fe_loose *f, const fe_loose *g, fe_limb_t b) {
fe_limb_t x = f->v[i] ^ g->v[i];