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al_fixadd(3)                                                      al_fixadd(3)

NAME
       al_fixadd - Allegro 5 API

SYNOPSIS

              #include <allegro5/allegro.h>

              al_fixed al_fixadd(al_fixed x, al_fixed y);

DESCRIPTION
       Although fixed point numbers can be added with the normal + integer
       operator, that doesn't provide any protection against overflow.  If
       overflow is a problem, you should use this function instead.  It is
       slower than using integer operators, but if an overflow occurs it will
       set Allegro's errno and clamp the result, rather than just letting it
       wrap.

       Example:

                  al_fixed result;

                  /* This will put 5035 into `result'. */
                  result = al_fixadd(al_itofix(5000), al_itofix(35));

                  /* Sets errno and puts -32768 into `result'. */
                  result = al_fixadd(al_itofix(-31000), al_itofix(-3000));
                  assert(!al_get_errno()); /* This will fail. */

RETURN VALUE
       Returns the clamped result of adding x to y, setting Allegro's errno to
       ERANGE if there was an overflow.

SEE ALSO
       al_fixsub(3), al_fixmul(3), al_fixdiv(3).

Allegro reference manual                                          al_fixadd(3)