1/* Copyright (C) 2002-2017 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
18
19#ifndef _LIST_H
20
21#ifndef __need_list_t
22# define _LIST_H 1
23#endif
24
25/* The definitions of this file are adopted from those which can be
26 found in the Linux kernel headers to enable people familiar with
27 the latter find their way in these sources as well. */
28
29
30#if defined __need_list_t || defined _LIST_H
31# ifndef __list_t_defined
32# define __list_t_defined
33/* Basic type for the double-link list. */
34typedef struct list_head
35{
36 struct list_head *next;
37 struct list_head *prev;
38} list_t;
39# endif
40# undef __need_list_t
41#endif
42
43#ifdef _LIST_H
44
45# include <atomic.h>
46
47/* Define a variable with the head and tail of the list. */
48# define LIST_HEAD(name) \
49 list_t name = { &(name), &(name) }
50
51/* Initialize a new list head. */
52# define INIT_LIST_HEAD(ptr) \
53 (ptr)->next = (ptr)->prev = (ptr)
54
55
56/* Add new element at the head of the list. */
57static inline void
58list_add (list_t *newp, list_t *head)
59{
60 newp->next = head->next;
61 newp->prev = head;
62 head->next->prev = newp;
63 atomic_write_barrier ();
64 head->next = newp;
65}
66
67
68/* Remove element from list. */
69static inline void
70list_del (list_t *elem)
71{
72 elem->next->prev = elem->prev;
73 elem->prev->next = elem->next;
74}
75
76
77/* Join two lists. */
78static inline void
79list_splice (list_t *add, list_t *head)
80{
81 /* Do nothing if the list which gets added is empty. */
82 if (add != add->next)
83 {
84 add->next->prev = head;
85 add->prev->next = head->next;
86 head->next->prev = add->prev;
87 head->next = add->next;
88 }
89}
90
91
92/* Get typed element from list at a given position. */
93# define list_entry(ptr, type, member) \
94 ((type *) ((char *) (ptr) - (unsigned long) (&((type *) 0)->member)))
95
96
97
98/* Iterate forward over the elements of the list. */
99# define list_for_each(pos, head) \
100 for (pos = (head)->next; pos != (head); pos = pos->next)
101
102
103/* Iterate forward over the elements of the list. */
104# define list_for_each_prev(pos, head) \
105 for (pos = (head)->prev; pos != (head); pos = pos->prev)
106
107
108/* Iterate backwards over the elements list. The list elements can be
109 removed from the list while doing this. */
110# define list_for_each_prev_safe(pos, p, head) \
111 for (pos = (head)->prev, p = pos->prev; \
112 pos != (head); \
113 pos = p, p = pos->prev)
114
115#endif /* _LIST_H */
116
117#endif /* list.h */
118