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fixadd(3) Allegro manual fixadd(3)

NAME

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)

version 4.4.3 Allegro