+
+# if HAVE_CLOCK_GETTIME
+# ifndef EV_USE_MONOTONIC
+# define EV_USE_MONOTONIC 1
+# endif
+# ifndef EV_USE_REALTIME
+# define EV_USE_REALTIME 1
+# endif
+# else
+# ifndef EV_USE_MONOTONIC
+# define EV_USE_MONOTONIC 0
+# endif
+# ifndef EV_USE_REALTIME
+# define EV_USE_REALTIME 0
+# endif
+# endif
+
+# if HAVE_SELECT && HAVE_SYS_SELECT_H && !defined (EV_USE_SELECT)
+# define EV_USE_SELECT 1
+# else
+# define EV_USE_SELECT 0
+# endif
+
+# if HAVE_POLL && HAVE_POLL_H && !defined (EV_USE_POLL)
+# define EV_USE_POLL 1
+# else
+# define EV_USE_POLL 0
+# endif
+
+# if HAVE_EPOLL_CTL && HAVE_SYS_EPOLL_H && !defined (EV_USE_EPOLL)
+# define EV_USE_EPOLL 1
+# else
+# define EV_USE_EPOLL 0
+# endif
+
+# if HAVE_KQUEUE && HAVE_SYS_EVENT_H && HAVE_SYS_QUEUE_H && !defined (EV_USE_KQUEUE)
+# define EV_USE_KQUEUE 1
+# else
+# define EV_USE_KQUEUE 0
+# endif
+
+# if HAVE_PORT_H && HAVE_PORT_CREATE && !defined (EV_USE_PORT)
+# define EV_USE_PORT 1
+# else
+# define EV_USE_PORT 0
+# endif
+