al_set_keyboard_leds - Allegro 5 API

       Overrides  the  state of the keyboard LED indicators.  Set leds to a combination of the keyboard modifier
       flags to enable the corresponding LED  indicators  (ALLEGRO_KEYMOD_NUMLOCK,  ALLEGRO_KEYMOD_CAPSLOCK  and
       ALLEGRO_KEYMOD_SCROLLLOCK  are  supported)  or to -1 to return to default behavior.  False is returned if
       the current keyboard driver cannot set LED indicators.

       al_set_keyboard_leds - Allegro 5 API

al_can_set_keyboard_leds(3alleg5)

Allegro reference manual                                                           al_set_keyboard_leds(3alleg5)

              #include <allegro5/allegro.h>

              bool al_set_keyboard_leds(int leds)