al_add_timer_count - Allegro 5 API

       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.

       al_add_timer_count - Allegro 5 API

al_set_timer_count(3alleg5)

Allegro reference manual                                                             al_add_timer_count(3alleg5)

              #include <allegro5/allegro.h>

              void al_add_timer_count(ALLEGRO_TIMER *timer, int64_t diff)