rb_fd_isset       338 include/ruby/intern.h #define rb_fd_isset(n, f)	rb_w32_fdisset((n), (f)->fdset)
rb_fd_isset       355 include/ruby/intern.h #define rb_fd_isset(n, f) FD_ISSET((n), (f))
rb_fd_isset      3502 thread.c       rb_fd_isset(int n, const rb_fdset_t *fds)