#ifndef _LINUX_LIST_H

#define _LINUX_LIST_H

/*

 * Simple doubly linked list implementation.

 *

 * Some of the internal functions ("__xxx") are useful when

 * manipulating whole lists rather than single entries, as

 * sometimes we already know the next/prev entries and we can

 * generate better code by using them directly rather than

 * using the generic single-entry routines.

 */

struct list_head {

  struct list_head *next, *prev;

};

#define LIST_HEAD_INIT(name) { &(name), &(name) }

#define LIST_HEAD(name) \

	struct list_head name = LIST_HEAD_INIT(name)

#define INIT_LIST_HEAD(ptr) do { \

	(ptr)->next = (ptr); (ptr)->prev = (ptr); \

} while (0)

/*

 * Insert a new entry between two known consecutive entries. 

 *

 * This is only for internal list manipulation where we know

 * the prev/next entries already!

 */

static inline void

__list_add(struct list_head *new,

	   struct list_head *prev, struct list_head *next)

{

  next->prev = new;

  new->next = next;

  new->prev = prev;

  prev->next = new;

}

/**

 * list_add - add a new entry

 * @new: new entry to be added

 * @head: list head to add it after

 *

 * Insert a new entry after the specified head.

 * This is good for implementing stacks.

 */

static inline void list_add(struct list_head *new, struct list_head *head)

{

  __list_add(new, head, head->next);

}

/**

 * list_add_tail - add a new entry

 * @new: new entry to be added

 * @head: list head to add it before

 *

 * Insert a new entry before the specified head.

 * This is useful for implementing queues.

 */

static inline void

list_add_tail(struct list_head *new, struct list_head *head)

{

  __list_add(new, head->prev, head);

}

/*

 * Delete a list entry by making the prev/next entries

 * point to each other.

 *

 * This is only for internal list manipulation where we know

 * the prev/next entries already!

 */

static inline void

__list_del(struct list_head *prev, struct list_head *next)

{

  next->prev = prev;

  prev->next = next;

}

/**

 * list_del - deletes entry from list.

 * @entry: the element to delete from the list.

 * Note: list_empty on entry does not return true after this, the entry is in an undefined state.

 */

static inline void list_del(struct list_head *entry)

{

  __list_del(entry->prev, entry->next);

  entry->next = (void *) 0;

  entry->prev = (void *) 0;

}

/**

 * list_del_init - deletes entry from list and reinitialize it.

 * @entry: the element to delete from the list.

 */

static inline void list_del_init(struct list_head *entry)

{

  __list_del(entry->prev, entry->next);

  INIT_LIST_HEAD(entry);

}

/**

 * list_move - delete from one list and add as another's head

 * @list: the entry to move

 * @head: the head that will precede our entry

 */

static inline void

list_move(struct list_head *list, struct list_head *head)

{

  __list_del(list->prev, list->next);

  list_add(list, head);

}

/**

 * list_move_tail - delete from one list and add as another's tail

 * @list: the entry to move

 * @head: the head that will follow our entry

 */

static inline void

list_move_tail(struct list_head *list, struct list_head *head)

{

  __list_del(list->prev, list->next);

  list_add_tail(list, head);

}

/**

 * list_empty - tests whether a list is empty

 * @head: the list to test.

 */

static inline int list_empty(struct list_head *head)

{

  return head->next == head;

}

static inline void

__list_splice(struct list_head *list, struct list_head *head)

{

  struct list_head *first = list->next;

  struct list_head *last = list->prev;

  struct list_head *at = head->next;

  first->prev = head;

  head->next = first;

  last->next = at;

  at->prev = last;

}

/**

 * list_splice - join two lists

 * @list: the new list to add.

 * @head: the place to add it in the first list.

 */

static inline void

list_splice(struct list_head *list, struct list_head *head)

{

  if (!list_empty(list))

    __list_splice(list, head);

}

/**

 * list_splice_init - join two lists and reinitialise the emptied list.

 * @list: the new list to add.

 * @head: the place to add it in the first list.

 *

 * The list at @list is reinitialised

 */

static inline void

list_splice_init(struct list_head *list, struct list_head *head)

{

  if (!list_empty(list)) {

    __list_splice(list, head);

    INIT_LIST_HEAD(list);

  }

}

/**

 * list_entry - get the struct for this entry

 * @ptr:	the &struct list_head pointer.

 * @type:	the type of the struct this is embedded in.

 * @member:	the name of the list_struct within the struct.

 */

#define list_entry(ptr, type, member) \

	((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

/**

 * list_for_each_safe	-	iterate over a list safe against removal of list entry

 * @pos:	the &struct list_head to use as a loop counter.

 * @n:		another &struct list_head to use as temporary storage

 * @head:	the head for your list.

 */

#define list_for_each_safe(pos, n, head) \

	for (pos = (head)->next, n = pos->next; pos != (head); \

		pos = n, n = pos->next)

/**

 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry

 * @pos:	the type * to use as a loop counter.

 * @n:		another type * to use as temporary storage

 * @head:	the head for your list.

 * @member:	the name of the list_struct within the struct.

 */

#define list_for_each_entry_safe(pos, n, head, member)			\

	for (pos = list_entry((head)->next, typeof(*pos), member),	\

		n = list_entry(pos->member.next, typeof(*pos), member);	\

	     &pos->member != (head); 					\

	     pos = n, n = list_entry(n->member.next, typeof(*n), member))

#endif