/*
   Copyright (c) 2008-2011 Gluster, Inc. <http://www.gluster.com>
   This file is part of GlusterFS.

   GlusterFS is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published
   by the Free Software Foundation; either version 3 of the License,
   or (at your option) any later version.

   GlusterFS is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see
   <http://www.gnu.org/licenses/>.
*/

#ifndef _LLIST_H
#define _LLIST_H


struct list_head {
	struct list_head *next;
	struct list_head *prev;
};


#define INIT_LIST_HEAD(head) do {			\
		(head)->next = (head)->prev = head;	\
	} while (0)


static inline void
list_add (struct list_head *new, struct list_head *head)
{
	new->prev = head;
	new->next = head->next;

	new->prev->next = new;
	new->next->prev = new;
}


static inline void
list_add_tail (struct list_head *new, struct list_head *head)
{
	new->next = head;
	new->prev = head->prev;

	new->prev->next = new;
	new->next->prev = new;
}


static inline void
list_del (struct list_head *old)
{
	old->prev->next = old->next;
	old->next->prev = old->prev;

	old->next = (void *)0xbabebabe;
	old->prev = (void *)0xcafecafe;
}


static inline void
list_del_init (struct list_head *old)
{
	old->prev->next = old->next;
	old->next->prev = old->prev;

	old->next = old;
	old->prev = old;
}


static inline void
list_move (struct list_head *list, struct list_head *head)
{
	list_del (list);
	list_add (list, head);
}


static inline void
list_move_tail (struct list_head *list, struct list_head *head)
{
	list_del (list);
	list_add_tail (list, head);
}


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)
{
	(list->prev)->next = (head->next);
	(head->next)->prev = (list->prev);

	(head)->next = (list->next);
	(list->next)->prev = (head);
}


static inline void
list_splice (struct list_head *list, struct list_head *head)
{
	if (list_empty (list))
		return;

	__list_splice (list, head);
}


/* Splice moves @list to the head of the list at @head. */
static inline void
list_splice_init (struct list_head *list, struct list_head *head)
{
	if (list_empty (list))
		return;

	__list_splice (list, head);
	INIT_LIST_HEAD (list);
}


static inline void
__list_append (struct list_head *list, struct list_head *head)
{
	(head->prev)->next = (list->next);
        (list->next)->prev = (head->prev);
        (head->prev) = (list->prev);
        (list->prev)->next = head;
}


static inline void
list_append (struct list_head *list, struct list_head *head)
{
	if (list_empty (list))
		return;

	__list_append (list, head);
}


/* Append moves @list to the end of @head */
static inline void
list_append_init (struct list_head *list, struct list_head *head)
{
	if (list_empty (list))
		return;

	__list_append (list, head);
	INIT_LIST_HEAD (list);
}


#define list_entry(ptr, type, member)					\
	((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))


#define list_for_each(pos, head)                                        \
	for (pos = (head)->next; pos != (head); pos = pos->next)


#define list_for_each_entry(pos, head, member)				\
	for (pos = list_entry((head)->next, typeof(*pos), member);	\
	     &pos->member != (head); 					\
	     pos = list_entry(pos->member.next, typeof(*pos), member))


#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 /* _LLIST_H */