Provided by: allegro4-doc_4.4.2-10_all
fixmul - Multiplies two fixed point values together. Allegro game programming library.
#include <allegro.h> fixed fixmul(fixed x, fixed y);
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);
Returns the clamped result of multiplying `x' by `y', setting `errno' to ERANGE if there was an overflow.