fp_tabselect
ATTRIBUTE_WARN_UNUSED_RET int fp_tabselect(fp_t out, u8 idx, fp_src_t *tab, u8 tabsize);
ret = fp_tabselect(&x, idx, tab_x_t, 2); EG(ret, err);
ret = fp_tabselect(&y, idx, tab_y_t, 2); EG(ret, err);
ret = fp_tabselect(&u, idx, tab_u_t, 2); EG(ret, err);
ret = fp_tabselect(&v, idx, tab_v_t, 2); EG(ret, err);