Merged in rnouse/nuttx (pull request #13)

Add simple `epoll' wrapper around `poll'

include/sys/epoll.h

@@ -0,0 +1,59 @@
+#ifndef _EPOLL__H
+#define _EPOLL__H
+
+#include <poll.h>
+
+enum EPOLL_EVENTS
+  {
+    EPOLLIN = POLLIN,
+#define EPOLLIN EPOLLIN
+    EPOLLPRI = POLLPRI,
+#define EPOLLPRI EPOLLPRI
+    EPOLLOUT = POLLOUT,
+#define EPOLLOUT EPOLLOUT
+    EPOLLRDNORM = POLLRDNORM,
+#define EPOLLRDNORM EPOLLRDNORM
+    EPOLLRDBAND = POLLRDBAND,
+#define EPOLLRDBAND EPOLLRDBAND
+    EPOLLWRNORM = POLLWRNORM,
+#define EPOLLWRNORM EPOLLWRNORM
+    EPOLLWRBAND = POLLWRBAND,
+#define EPOLLWRBAND EPOLLWRBAND
+    EPOLLERR = POLLERR,
+#define EPOLLERR EPOLLERR
+    EPOLLHUP = POLLHUP,
+#define EPOLLHUP EPOLLHUP
+  };
+
+#define EPOLL_CTL_ADD 1 /* Add a file descriptor to the interface.  */
+#define EPOLL_CTL_DEL 2 /* Remove a file descriptor from the interface.  */
+#define EPOLL_CTL_MOD 3 /* Change file descriptor epoll_event structure.  */
+
+typedef union poll_data
+{
+  int         fd;       /* The descriptor being polled */
+} epoll_data_t;
+
+struct epoll_event
+{
+  epoll_data_t data;
+  sem_t       *sem;      /* Pointer to semaphore used to post output event */
+  pollevent_t  events;   /* The input event flags */
+  pollevent_t  revents;  /* The output event flags */
+  FAR void    *priv;     /* For use by drivers */
+};
+
+struct epoll_head
+{
+  int size;
+  int occupied;
+  struct epoll_event *evs;
+};
+
+int epoll_create(int size);
+int epoll_ctl(int epfd, int op, int fd, struct epoll_event *ev);
+int epoll_wait(int epfd, struct epoll_event *evs, int maxevents, int timeout);
+
+void epoll_close(int epfd);
+
+#endif