al_ftofix - Allegro 5 API

       Converts  a  floating point value to fixed point.  Unlike al_itofix(3alleg5), this function clamps values
       which could overflow the type conversion, setting Allegro’s errno  to  ERANGE  in  the  process  if  this
       happens.

       Example:

              al_fixed number;

              number = al_itofix(-40000);
              assert(al_fixfloor(number) == -32768);

              number = al_itofix(64000);
              assert(al_fixfloor(number) == 32767);
              assert(!al_get_errno()); /* This will fail. */

       al_ftofix - Allegro 5 API

       Returns  the  value  of the floating point value converted to fixed point clamping overflows (and setting
       Allegro’s errno).

al_fixtof(3alleg5), al_itofix(3alleg5), al_fixtoi(3alleg5), al_get_errno(3alleg5)

Allegro reference manual                                                                      al_ftofix(3alleg5)

              #include <allegro5/allegro.h>

              al_fixed al_ftofix(double x);