+ size_t n = mm->n;
+
+ /* --- Check for serious Karatsuba reduction --- */
+
+ if (n > KARATSUBA_CUTOFF * 3) {
+ mp al;
+ mpw *vl;
+ mp *u;
+
+ if (MP_LEN(a) >= n)
+ vl = a->v + n;
+ else
+ vl = a->vl;
+ mp_build(&al, a->v, vl);
+ u = mp_mul(MP_NEW, &al, mm->mi);
+ if (MP_LEN(u) > n)
+ u->vl = u->v + n;
+ u = mp_mul(u, u, mm->m);
+ d = mp_add(d, a, u);
+ mp_drop(u);
+ }