#ifndef _LINUX_POLL_H
  #define _LINUX_POLL_H

  
  #include <linux/compiler.h>

  #include <linux/ktime.h>

  #include <linux/wait.h>
  #include <linux/string.h>

  #include <linux/fs.h>

  #include <linux/sysctl.h>

  #include <asm/uaccess.h>

  #include <uapi/linux/poll.h>

  extern struct ctl_table epoll_table[]; /* for sysctl */

  /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating
     additional memory. */
  #define MAX_STACK_ALLOC 832
  #define FRONTEND_STACK_ALLOC	256
  #define SELECT_STACK_ALLOC	FRONTEND_STACK_ALLOC
  #define POLL_STACK_ALLOC	FRONTEND_STACK_ALLOC
  #define WQUEUES_STACK_ALLOC	(MAX_STACK_ALLOC - FRONTEND_STACK_ALLOC)
  #define N_INLINE_POLL_ENTRIES	(WQUEUES_STACK_ALLOC / sizeof(struct poll_table_entry))

  #define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)

  struct poll_table_struct;
  
  /* 
   * structures and helpers for f_op->poll implementations
   */
  typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);

  /*
   * Do not touch the structure directly, use the access functions
   * poll_does_not_wait() and poll_requested_events() instead.
   */

  typedef struct poll_table_struct {

  	poll_queue_proc _qproc;
  	unsigned long _key;

  } poll_table;
  
  static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
  {

  	if (p && p->_qproc && wait_address)
  		p->_qproc(filp, wait_address, p);
  }
  
  /*
   * Return true if it is guaranteed that poll will not wait. This is the case
   * if the poll() of another file descriptor in the set got an event, so there
   * is no need for waiting.
   */
  static inline bool poll_does_not_wait(const poll_table *p)
  {
  	return p == NULL || p->_qproc == NULL;
  }
  
  /*
   * Return the set of events that the application wants to poll for.
   * This is useful for drivers that need to know whether a DMA transfer has
   * to be started implicitly on poll(). You typically only want to do that
   * if the application is actually polling for POLLIN and/or POLLOUT.
   */
  static inline unsigned long poll_requested_events(const poll_table *p)
  {
  	return p ? p->_key : ~0UL;

  }
  
  static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
  {

  	pt->_qproc = qproc;
  	pt->_key   = ~0UL; /* all events enabled */

  }

  struct poll_table_entry {

  	struct file *filp;

  	unsigned long key;

  	wait_queue_t wait;

  	wait_queue_head_t *wait_address;

  };

  /*

   * Structures and helpers for select/poll syscall

   */
  struct poll_wqueues {
  	poll_table pt;

  	struct poll_table_page *table;
  	struct task_struct *polling_task;
  	int triggered;

  	int error;

  	int inline_index;
  	struct poll_table_entry inline_entries[N_INLINE_POLL_ENTRIES];

  };
  
  extern void poll_initwait(struct poll_wqueues *pwq);
  extern void poll_freewait(struct poll_wqueues *pwq);

  extern int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
  				 ktime_t *expires, unsigned long slack);

  extern u64 select_estimate_accuracy(struct timespec64 *tv);

  
  static inline int poll_schedule(struct poll_wqueues *pwq, int state)
  {
  	return poll_schedule_timeout(pwq, state, NULL, 0);
  }

  
  /*

   * Scalable version of the fd_set.

   */
  
  typedef struct {
  	unsigned long *in, *out, *ex;
  	unsigned long *res_in, *res_out, *res_ex;
  } fd_set_bits;
  
  /*
   * How many longwords for "nr" bits?
   */
  #define FDS_BITPERLONG	(8*sizeof(long))
  #define FDS_LONGS(nr)	(((nr)+FDS_BITPERLONG-1)/FDS_BITPERLONG)
  #define FDS_BYTES(nr)	(FDS_LONGS(nr)*sizeof(long))
  
  /*
   * We do a VERIFY_WRITE here even though we are only reading this time:
   * we'll write to it eventually..
   *
   * Use "unsigned long" accesses to let user-mode fd_set's be long-aligned.
   */
  static inline
  int get_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
  {
  	nr = FDS_BYTES(nr);
  	if (ufdset)
  		return copy_from_user(fdset, ufdset, nr) ? -EFAULT : 0;
  
  	memset(fdset, 0, nr);
  	return 0;
  }
  
  static inline unsigned long __must_check
  set_fd_set(unsigned long nr, void __user *ufdset, unsigned long *fdset)
  {
  	if (ufdset)
  		return __copy_to_user(ufdset, fdset, FDS_BYTES(nr));
  	return 0;
  }
  
  static inline
  void zero_fd_set(unsigned long nr, unsigned long *fdset)
  {
  	memset(fdset, 0, FDS_BYTES(nr));
  }

  #define MAX_INT64_SECONDS (((s64)(~((u64)0)>>1)/HZ)-1)

  extern int do_select(int n, fd_set_bits *fds, struct timespec64 *end_time);

  extern int do_sys_poll(struct pollfd __user * ufds, unsigned int nfds,

  		       struct timespec64 *end_time);

  extern int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,

  			   fd_set __user *exp, struct timespec64 *end_time);

  extern int poll_select_set_timeout(struct timespec64 *to, time64_t sec,
  				   long nsec);

  #endif /* _LINUX_POLL_H */