al_get_max_haptic_effects man page
al_get_max_haptic_effects — Allegro 5 API
#include <allegro5/allegro.h> int al_get_max_haptic_effects(ALLEGRO_HAPTIC *hap)
Returns the maximum amount of haptic effects that can be uploaded to the device. This depends on the operating system, driver, platform and the device itself. This may return a value as low as 1.
[Unstable API]: Perhaps could be simplified due to limited support for all the exposed features across all of the platforms. Awaiting feedback from users.