fixadd(3) Allegro manual fixadd(3)NAMEfixadd - 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 ALSOfixsub(3), fixmul(3), fixdiv(3)Allegro version 4.4.2 fixadd(3)
