ec_montgomery_crv_init
ATTRIBUTE_WARN_UNUSED_RET int ec_montgomery_crv_init(ec_montgomery_crv_t crv, fp_src_t a, fp_src_t b, nn_src_t order);
ret = ec_montgomery_crv_init(montgomery_crv, &A, &B, &(edwards_crv->order));
ret = ec_montgomery_crv_init(montgomery_crv, &A, &gamma_inv, &(shortw_crv->order));