rb_fd_ptr        3542 thread.c               r = rb_fd_ptr(readfds);
rb_fd_ptr        3546 thread.c               w = rb_fd_ptr(writefds);
rb_fd_ptr        3550 thread.c               e = rb_fd_ptr(exceptfds);
rb_fd_ptr         659 thread_win32.c         r = rb_fd_ptr(readfds);
rb_fd_ptr         663 thread_win32.c         w = rb_fd_ptr(writefds);
rb_fd_ptr         667 thread_win32.c         e = rb_fd_ptr(exceptfds);