list.h revision 9663:ace9a2ac3683 
1/*
2 * list.h - Linked list implementation. Part of the Linux-NTFS project.
3 *
4 * Copyright (c) 2000-2002 Anton Altaparmakov and others
5 *
6 * This program/include file is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as published
8 * by the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program/include file is distributed in the hope that it will be
12 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
13 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program (in the main directory of the Linux-NTFS
18 * distribution in the file COPYING); if not, write to the Free Software
19 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20 */
21
22#ifndef _NTFS_LIST_H
23#define _NTFS_LIST_H
24
25/**
26 * struct list_head - Simple doubly linked list implementation.
27 *
28 * Copied from Linux kernel 2.4.2-ac18 into Linux-NTFS (with minor
29 * modifications). - AIA
30 *
31 * Some of the internal functions ("__xxx") are useful when
32 * manipulating whole lists rather than single entries, as
33 * sometimes we already know the next/prev entries and we can
34 * generate better code by using them directly rather than
35 * using the generic single-entry routines.
36 */
37struct list_head {
38	struct list_head *next, *prev;
39};
40
41#define LIST_HEAD_INIT(name) { &(name), &(name) }
42
43#define LIST_HEAD(name) \
44	struct list_head name = LIST_HEAD_INIT(name)
45
46#define INIT_LIST_HEAD(ptr) do { \
47	(ptr)->next = (ptr); (ptr)->prev = (ptr); \
48} while (0)
49
50/**
51 * __list_add - Insert a new entry between two known consecutive entries.
52 * @new:
53 * @prev:
54 * @next:
55 *
56 * This is only for internal list manipulation where we know the prev/next
57 * entries already!
58 */
59static __inline__ void __list_add(struct list_head * new,
60		struct list_head * prev, struct list_head * next)
61{
62	next->prev = new;
63	new->next = next;
64	new->prev = prev;
65	prev->next = new;
66}
67
68/**
69 * list_add - add a new entry
70 * @new:	new entry to be added
71 * @head:	list head to add it after
72 *
73 * Insert a new entry after the specified head.
74 * This is good for implementing stacks.
75 */
76static __inline__ void list_add(struct list_head *new, struct list_head *head)
77{
78	__list_add(new, head, head->next);
79}
80
81/**
82 * list_add_tail - add a new entry
83 * @new:	new entry to be added
84 * @head:	list head to add it before
85 *
86 * Insert a new entry before the specified head.
87 * This is useful for implementing queues.
88 */
89static __inline__ void list_add_tail(struct list_head *new, struct list_head *head)
90{
91	__list_add(new, head->prev, head);
92}
93
94/**
95 * __list_del -
96 * @prev:
97 * @next:
98 *
99 * Delete a list entry by making the prev/next entries point to each other.
100 *
101 * This is only for internal list manipulation where we know the prev/next
102 * entries already!
103 */
104static __inline__ void __list_del(struct list_head * prev,
105		struct list_head * next)
106{
107	next->prev = prev;
108	prev->next = next;
109}
110
111/**
112 * list_del - deletes entry from list.
113 * @entry:	the element to delete from the list.
114 *
115 * Note: list_empty on entry does not return true after this, the entry is in
116 * an undefined state.
117 */
118static __inline__ void list_del(struct list_head *entry)
119{
120	__list_del(entry->prev, entry->next);
121}
122
123/**
124 * list_del_init - deletes entry from list and reinitialize it.
125 * @entry:	the element to delete from the list.
126 */
127static __inline__ void list_del_init(struct list_head *entry)
128{
129	__list_del(entry->prev, entry->next);
130	INIT_LIST_HEAD(entry);
131}
132
133/**
134 * list_empty - tests whether a list is empty
135 * @head:	the list to test.
136 */
137static __inline__ int list_empty(struct list_head *head)
138{
139	return head->next == head;
140}
141
142/**
143 * list_splice - join two lists
144 * @list:	the new list to add.
145 * @head:	the place to add it in the first list.
146 */
147static __inline__ void list_splice(struct list_head *list,
148		struct list_head *head)
149{
150	struct list_head *first = list->next;
151
152	if (first != list) {
153		struct list_head *last = list->prev;
154		struct list_head *at = head->next;
155
156		first->prev = head;
157		head->next = first;
158
159		last->next = at;
160		at->prev = last;
161	}
162}
163
164/**
165 * list_entry - get the struct for this entry
166 * @ptr:	the &struct list_head pointer.
167 * @type:	the type of the struct this is embedded in.
168 * @member:	the name of the list_struct within the struct.
169 */
170#define list_entry(ptr, type, member) \
171	((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
172
173/**
174 * list_for_each - iterate over a list
175 * @pos:	the &struct list_head to use as a loop counter.
176 * @head:	the head for your list.
177 */
178#define list_for_each(pos, head) \
179	for (pos = (head)->next; pos != (head); pos = pos->next)
180
181/**
182 * list_for_each_safe	-	iterate over a list safe against removal of list entry
183 * @pos:	the &struct list_head to use as a loop counter.
184 * @n:		another &struct list_head to use as temporary storage
185 * @head:	the head for your list.
186 */
187#define list_for_each_safe(pos, n, head) \
188	for (pos = (head)->next, n = pos->next; pos != (head); \
189		pos = n, n = pos->next)
190
191#endif /* defined _NTFS_LIST_H */
192
193