fixadd man page

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)

Referenced By

fixdiv(3), fixmul(3), fixsub(3).

version 4.4.2 Allegro Allegro manual