al_add_timer_count
void al_add_timer_count(ALLEGRO_TIMER *timer, int64_t diff)
Add diff to the timer's counter value. This is similar to writing:
al_set_timer_count(timer, al_get_timer_count(timer) + diff);except that the addition is performed atomically, so no ticks will be lost.
See also: al_set_timer_count
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