curve_edwards_montgomery_check
ATTRIBUTE_WARN_UNUSED_RET int curve_edwards_montgomery_check(ec_edwards_crv_src_t edwards_crv, ec_montgomery_crv_src_t montgomery_crv, fp_src_t alpha_edwards);
ret = curve_edwards_montgomery_check(in_edwards->crv, montgomery_crv, alpha_edwards); EG(ret, err);
ret = curve_edwards_montgomery_check(edwards_crv, in_montgomery->crv, alpha); EG(ret, err);