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 ntfs_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 */
37 struct ntfs_list_head {
38 struct ntfs_list_head *next, *prev;
39 };
40
41 #define NTFS_LIST_HEAD_INIT(name) { &(name), &(name) }
42
43 #define NTFS_LIST_HEAD(name) \
44 struct ntfs_list_head name = NTFS_LIST_HEAD_INIT(name)
45
46 #define NTFS_INIT_LIST_HEAD(ptr) do { \
47 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
48 } while (0)
49
50 /**
51 * __ntfs_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 */
__ntfs_list_add(struct ntfs_list_head * new,struct ntfs_list_head * prev,struct ntfs_list_head * next)59 static __inline__ void __ntfs_list_add(struct ntfs_list_head * new,
60 struct ntfs_list_head * prev, struct ntfs_list_head * next)
61 {
62 next->prev = new;
63 new->next = next;
64 new->prev = prev;
65 prev->next = new;
66 }
67
68 /**
69 * ntfs_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 */
ntfs_list_add(struct ntfs_list_head * new,struct ntfs_list_head * head)76 static __inline__ void ntfs_list_add(struct ntfs_list_head *new,
77 struct ntfs_list_head *head)
78 {
79 __ntfs_list_add(new, head, head->next);
80 }
81
82 /**
83 * ntfs_list_add_tail - add a new entry
84 * @new: new entry to be added
85 * @head: list head to add it before
86 *
87 * Insert a new entry before the specified head.
88 * This is useful for implementing queues.
89 */
ntfs_list_add_tail(struct ntfs_list_head * new,struct ntfs_list_head * head)90 static __inline__ void ntfs_list_add_tail(struct ntfs_list_head *new,
91 struct ntfs_list_head *head)
92 {
93 __ntfs_list_add(new, head->prev, head);
94 }
95
96 /**
97 * __ntfs_list_del -
98 * @prev:
99 * @next:
100 *
101 * Delete a list entry by making the prev/next entries point to each other.
102 *
103 * This is only for internal list manipulation where we know the prev/next
104 * entries already!
105 */
__ntfs_list_del(struct ntfs_list_head * prev,struct ntfs_list_head * next)106 static __inline__ void __ntfs_list_del(struct ntfs_list_head * prev,
107 struct ntfs_list_head * next)
108 {
109 next->prev = prev;
110 prev->next = next;
111 }
112
113 /**
114 * ntfs_list_del - deletes entry from list.
115 * @entry: the element to delete from the list.
116 *
117 * Note: ntfs_list_empty on entry does not return true after this, the entry is
118 * in an undefined state.
119 */
ntfs_list_del(struct ntfs_list_head * entry)120 static __inline__ void ntfs_list_del(struct ntfs_list_head *entry)
121 {
122 __ntfs_list_del(entry->prev, entry->next);
123 }
124
125 /**
126 * ntfs_list_del_init - deletes entry from list and reinitialize it.
127 * @entry: the element to delete from the list.
128 */
ntfs_list_del_init(struct ntfs_list_head * entry)129 static __inline__ void ntfs_list_del_init(struct ntfs_list_head *entry)
130 {
131 __ntfs_list_del(entry->prev, entry->next);
132 NTFS_INIT_LIST_HEAD(entry);
133 }
134
135 /**
136 * ntfs_list_empty - tests whether a list is empty
137 * @head: the list to test.
138 */
ntfs_list_empty(struct ntfs_list_head * head)139 static __inline__ int ntfs_list_empty(struct ntfs_list_head *head)
140 {
141 return head->next == head;
142 }
143
144 /**
145 * ntfs_list_splice - join two lists
146 * @list: the new list to add.
147 * @head: the place to add it in the first list.
148 */
ntfs_list_splice(struct ntfs_list_head * list,struct ntfs_list_head * head)149 static __inline__ void ntfs_list_splice(struct ntfs_list_head *list,
150 struct ntfs_list_head *head)
151 {
152 struct ntfs_list_head *first = list->next;
153
154 if (first != list) {
155 struct ntfs_list_head *last = list->prev;
156 struct ntfs_list_head *at = head->next;
157
158 first->prev = head;
159 head->next = first;
160
161 last->next = at;
162 at->prev = last;
163 }
164 }
165
166 /**
167 * ntfs_list_entry - get the struct for this entry
168 * @ptr: the &struct ntfs_list_head pointer.
169 * @type: the type of the struct this is embedded in.
170 * @member: the name of the list_struct within the struct.
171 */
172 #define ntfs_list_entry(ptr, type, member) \
173 ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
174
175 /**
176 * ntfs_list_for_each - iterate over a list
177 * @pos: the &struct ntfs_list_head to use as a loop counter.
178 * @head: the head for your list.
179 */
180 #define ntfs_list_for_each(pos, head) \
181 for (pos = (head)->next; pos != (head); pos = pos->next)
182
183 /**
184 * ntfs_list_for_each_safe - iterate over a list safe against removal of list entry
185 * @pos: the &struct ntfs_list_head to use as a loop counter.
186 * @n: another &struct ntfs_list_head to use as temporary storage
187 * @head: the head for your list.
188 */
189 #define ntfs_list_for_each_safe(pos, n, head) \
190 for (pos = (head)->next, n = pos->next; pos != (head); \
191 pos = n, n = pos->next)
192
193 #endif /* defined _NTFS_LIST_H */
194
195