INT_BIT
if ((ports = calloc(65536 / INT_BIT, sizeof(int))) == NULL)
#define SET_PORT(p) do { ports[p / INT_BIT] |= 1 << (p % INT_BIT); } while (0)
#define CHK_PORT(p) (ports[p / INT_BIT] & (1 << (p % INT_BIT)))