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