FD_ISSET
#define FD_ISSET(fd, set) ((set)->bits[_FD_BITSINDEX(fd)] & _FD_BIT(fd))
#define FD_ISSET(n, p) ((p)->fds_bits[0] & (1<<(n)))
#define FD_ISSET(n, p) ((p)->fds_bits[0] & (1<<(n)))
#undef FD_ISSET
#define FD_ISSET(fd, maskp) \