ecp_sm2p256_point_double
ecp_sm2p256_point_double(R, &K);
ecp_sm2p256_point_double(R, Q);
ecp_sm2p256_point_double(&precomputed[2], &precomputed[1]);
ecp_sm2p256_point_double(R, R);
ecp_sm2p256_point_double(R, R);
ecp_sm2p256_point_double(R, R);
ecp_sm2p256_point_double(R, R);