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/* Doubly linked list macros compatible with Linux kernel's version
* Copyright (c) 2015 by Takashi Iwai <tiwai@suse.de>
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This program 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 Lesser General Public License for more details.
*/
#ifndef _LIST_H
#define _LIST_H
#include <stddef.h>
struct list_head {
struct list_head *next;
struct list_head *prev;
};
/* one-shot definition of a list head */
#define LIST_HEAD(x) \
struct list_head x = { &x, &x }
/* initialize a list head explicitly */
static inline void INIT_LIST_HEAD(struct list_head *p)
{
p->next = p->prev = p;
}
#define list_entry_offset(p, type, offset) \
((type *)((char *)(p) - (offset)))
/* list_entry - retrieve the original struct from list_head
* @p: list_head pointer
* @type: struct type
* @member: struct field member containing the list_head
*/
#define list_entry(p, type, member) \
list_entry_offset(p, type, offsetof(type, member))
/* list_for_each - iterate over the linked list
* @p: iterator, a list_head pointer variable
* @list: list_head pointer containing the list
*/
#define list_for_each(p, list) \
for (p = (list)->next; p != (list); p = p->next)
/* list_for_each_safe - iterate over the linked list, safe to delete
* @p: iterator, a list_head pointer variable
* @s: a temporary variable to keep the next, a list_head pointer, too
* @list: list_head pointer containing the list
*/
#define list_for_each_safe(p, s, list) \
for (p = (list)->next; s = p->next, p != (list); p = s)
/* list_add - prepend a list entry at the head
* @p: the new list entry to add
* @list: the list head
*/
static inline void list_add(struct list_head *p, struct list_head *list)
{
struct list_head *first = list->next;
p->next = first;
first->prev = p;
list->next = p;
p->prev = list;
}
/* list_add_tail - append a list entry at the tail
* @p: the new list entry to add
* @list: the list head
*/
static inline void list_add_tail(struct list_head *p, struct list_head *list)
{
struct list_head *last = list->prev;
last->next = p;
p->prev = last;
p->next = list;
list->prev = p;
}
/* list_insert - insert a new list entry between two known consecutive entries
* @p: the new entry to be inserted between prev and next
* @prev: the left-side entry
* @next: the right-side entry
*/
static inline void list_insert(struct list_head *p,
struct list_head *prev,
struct list_head *next)
{
next->prev = p;
p->next = next;
p->prev = prev;
prev->next = p;
}
/* list_del - delete the given list entry */
static inline void list_del(struct list_head *p)
{
p->prev->next = p->next;
p->next->prev = p->prev;
}
/* list_empty - returns 1 if the given list is empty */
static inline int list_empty(const struct list_head *p)
{
return p->next == p;
}
/* 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(const struct list_head *list,
struct list_head *head)
{
if (!list_empty(list)) {
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_init - join two lists and reinitialize the emptied list
* @list: the new list to add
* @head: the place to add it in the first list
*
* The list at @list is reinitialized
*/
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);
}
}
#endif /* _LIST_H */
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