clock_rel_after
extern bool clock_rel_after(clockid_t, const struct timespec *,
elapse = clock_rel_after(CLOCK_REALTIME, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_REALTIME, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_HIGHRES, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_REALTIME, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_REALTIME, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_HIGHRES, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_REALTIME, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_REALTIME, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_HIGHRES, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_REALTIME, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_REALTIME, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_HIGHRES, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_REALTIME, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_REALTIME, &start, &clock_to_100ms);
elapse = clock_rel_after(CLOCK_HIGHRES, &start, &clock_to_100ms);