-void ao_umul64_16(ao_int64_t *r, ao_int64_t *a, uint16_t b) {
- ao_umul64(r, a->low, b);
- r->high += a->high * b;
+static void ao_umul64(__ARG ao_int64_t *r, __ARG ao_int64_t *a, __ARG ao_int64_t *b) __reentrant {
+ __LOCAL ao_int64_t r2, r3;
+
+ ao_umul64_32_32(&r2, a->high, b->low);
+ ao_umul64_32_32(&r3, a->low, b->high);
+ ao_umul64_32_32(r, a->low, b->low);
+
+ r->high += r2.low + r3.low;