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fixmul(3)                       Allegro manual                       fixmul(3)

NAME
       fixmul - Multiplies two fixed point values together. Allegro game
       programming library.

SYNOPSIS
       #include <allegro.h>

       fixed fixmul(fixed x, fixed y);

DESCRIPTION
       A fixed point value can be multiplied or divided by an integer with the
       normal `*' and `/' operators. To multiply two fixed point values,
       though, you must use this function.

       If an overflow occurs, `errno' will be set and the maximum possible
       value will be returned, but `errno' is not cleared if the operation is
       successful. This means that if you are going to test for overflow you
       should set `errno=0' before calling fixmul(). Example:

          fixed result;

          /* This will put 30000 into `result'. */
          result = fixmul(itofix(10), itofix(3000));
          /* But this overflows, and sets `errno'. */
          result = fixmul(itofix(100), itofix(3000));
          ASSERT(!errno);

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

SEE ALSO
       fixadd(3), fixsub(3), fixdiv(3), ex3buf(3), excustom(3), exfixed(3),
       exspline(3), exstars(3), exupdate(3)

Allegro                          version 4.4.2                       fixmul(3)