fixadd(3)                       Allegro manual                       fixadd(3)



NAME
       fixadd - Safe function to add fixed point numbers clamping overflow.
       Allegro game programming library.

SYNOPSIS
       #include <allegro.h>


       fixed fixadd(fixed x, 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 `errno' and clamp the result, rather than just letting it wrap.
       Example:

          fixed result;
          /* This will put 5035 into `result'. */
          result = fixadd(itofix(5000), itofix(35));
          /* Sets `errno' and puts -32768 into `result'. */
          result = fixadd(itofix(-31000), itofix(-3000));
          ASSERT(!errno); /* This will fail. */

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


SEE ALSO
       fixsub(3), fixmul(3), fixdiv(3)



Allegro                          version 4.2.3                       fixadd(3)
