aff_pt_edwards_x_from_y
ATTRIBUTE_WARN_UNUSED_RET int aff_pt_edwards_x_from_y(fp_t x1, fp_t x2, fp_src_t y, ec_edwards_crv_src_t crv);
ret = aff_pt_edwards_x_from_y(&sqrt1, &sqrt2, &y, &edwards_curve_edwards448); EG(ret, err); /* Error or no square root found, this should not happen! */
ret = aff_pt_edwards_x_from_y(&sqrt1, &sqrt2, &y, edwards_curve); EG(ret, err); /* Error or no square root found, this should not happen! */