USER_CLOCKSOURCE
used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
return em_sti_start(p, USER_CLOCKSOURCE);
em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);