gf128_mul
h2 = gf128_mul(h, &t->tbls[0]);
h3 = gf128_mul(h, &t->tbls[1]);
h4 = gf128_mul(h2, &t->tbls[1]);
struct gf128 gf128_mul(struct gf128 v, struct gf128table *tbl);
v = gf128_mul(v, &agc->ghashtbl.tbls[0]);
v = gf128_mul(v, &agc->ghashtbl.tbls[0]);