al_set_timer_count - Allegro 5 API

       Set  the timer’s counter value.  The timer can be started or stopped.  The count value may be positive or
       negative, but will always be incremented by +1 at each tick.

       al_set_timer_count - Allegro 5 API

al_get_timer_count(3alleg5), al_add_timer_count(3alleg5)

Allegro reference manual                                                             al_set_timer_count(3alleg5)

              #include <allegro5/allegro.h>

              void al_set_timer_count(ALLEGRO_TIMER *timer, int64_t new_count)