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(3alleg4), fixmul(3alleg4), fixdiv(3alleg4)
