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(3alleg4), fixsub(3alleg4), fixdiv(3alleg4), ex3buf(3alleg4), excustom(3alleg4), exfixed(3alleg4), exspline(3alleg4), exstars(3alleg4), exupdate(3alleg4)