Provided by: allegro4-doc_4.4.2-4_all
fixadd - Safe function to add fixed point numbers clamping overflow. Allegro game programming library.
#include <allegro.h> fixed fixadd(fixed x, fixed y);
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. */
Returns the clamped result of adding `x' to `y', setting `errno' to ERANGE if there was an overflow.