1 #ifndef __LIST_H
2 #define __LIST_H
3
4 /* This file is from Linux Kernel (include/linux/list.h)
5 * and modified by simply removing hardware prefetching of list items.
6 * Here by copyright, credits attributed to wherever they belong.
7 * Kulesh Shanmugasundaram (kulesh [squiggly] isis.poly.edu)
8 */
9
10 /*
11 * Simple doubly linked list implementation.
12 *
13 * Some of the internal functions ("__xxx") are useful when
14 * manipulating whole lists rather than single entries, as
15 * sometimes we already know the next/prev entries and we can
16 * generate better code by using them directly rather than
17 * using the generic single-entry routines.
18 */
19
20 struct list_head {
21 struct list_head *next, *prev;
22 };
23
24 #define LIST_HEAD_INIT(name) { &(name), &(name) }
25
26 #define LIST_HEAD(name) \
27 struct list_head name = LIST_HEAD_INIT(name)
28
29 #define INIT_LIST_HEAD(ptr) do { \
30 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
31 } while (0)
32
33 /*
34 * Insert a new entry between two known consecutive entries.
35 *
36 * This is only for internal list manipulation where we know
37 * the prev/next entries already!
38 */
__list_add(struct list_head * new,struct list_head * prev,struct list_head * next)39 static inline void __list_add(struct list_head *new,
40 struct list_head *prev,
41 struct list_head *next)
42 {
43 next->prev = new;
44 new->next = next;
45 new->prev = prev;
46 prev->next = new;
47 }
48
49 /**
50 * list_add - add a new entry
51 * @new: new entry to be added
52 * @head: list head to add it after
53 *
54 * Insert a new entry after the specified head.
55 * This is good for implementing stacks.
56 */
list_add(struct list_head * new,struct list_head * head)57 static inline void list_add(struct list_head *new, struct list_head *head)
58 {
59 __list_add(new, head, head->next);
60 }
61
62 /**
63 * list_add_tail - add a new entry
64 * @new: new entry to be added
65 * @head: list head to add it before
66 *
67 * Insert a new entry before the specified head.
68 * This is useful for implementing queues.
69 */
list_add_tail(struct list_head * new,struct list_head * head)70 static inline void list_add_tail(struct list_head *new, struct list_head *head)
71 {
72 __list_add(new, head->prev, head);
73 }
74
75 /*
76 * Delete a list entry by making the prev/next entries
77 * point to each other.
78 *
79 * This is only for internal list manipulation where we know
80 * the prev/next entries already!
81 */
__list_del(struct list_head * prev,struct list_head * next)82 static inline void __list_del(struct list_head *prev, struct list_head *next)
83 {
84 next->prev = prev;
85 prev->next = next;
86 }
87
88 /**
89 * list_del - deletes entry from list.
90 * @entry: the element to delete from the list.
91 * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
92 */
list_del(struct list_head * entry)93 static inline void list_del(struct list_head *entry)
94 {
95 __list_del(entry->prev, entry->next);
96 entry->next = (void *) 0;
97 entry->prev = (void *) 0;
98 }
99
100 /**
101 * list_del_init - deletes entry from list and reinitialize it.
102 * @entry: the element to delete from the list.
103 */
list_del_init(struct list_head * entry)104 static inline void list_del_init(struct list_head *entry)
105 {
106 __list_del(entry->prev, entry->next);
107 INIT_LIST_HEAD(entry);
108 }
109
110 /**
111 * list_move - delete from one list and add as another's head
112 * @list: the entry to move
113 * @head: the head that will precede our entry
114 */
list_move(struct list_head * list,struct list_head * head)115 static inline void list_move(struct list_head *list, struct list_head *head)
116 {
117 __list_del(list->prev, list->next);
118 list_add(list, head);
119 }
120
121 /**
122 * list_move_tail - delete from one list and add as another's tail
123 * @list: the entry to move
124 * @head: the head that will follow our entry
125 */
list_move_tail(struct list_head * list,struct list_head * head)126 static inline void list_move_tail(struct list_head *list,
127 struct list_head *head)
128 {
129 __list_del(list->prev, list->next);
130 list_add_tail(list, head);
131 }
132
133 /**
134 * list_empty - tests whether a list is empty
135 * @head: the list to test.
136 */
list_empty(struct list_head * head)137 static inline int list_empty(struct list_head *head)
138 {
139 return head->next == head;
140 }
141
__list_splice(struct list_head * list,struct list_head * head)142 static inline void __list_splice(struct list_head *list,
143 struct list_head *head)
144 {
145 struct list_head *first = list->next;
146 struct list_head *last = list->prev;
147 struct list_head *at = head->next;
148
149 first->prev = head;
150 head->next = first;
151
152 last->next = at;
153 at->prev = last;
154 }
155
156 /**
157 * list_splice - join two lists
158 * @list: the new list to add.
159 * @head: the place to add it in the first list.
160 */
list_splice(struct list_head * list,struct list_head * head)161 static inline void list_splice(struct list_head *list, struct list_head *head)
162 {
163 if (!list_empty(list))
164 __list_splice(list, head);
165 }
166
167 /**
168 * list_splice_init - join two lists and reinitialise the emptied list.
169 * @list: the new list to add.
170 * @head: the place to add it in the first list.
171 *
172 * The list at @list is reinitialised
173 */
list_splice_init(struct list_head * list,struct list_head * head)174 static inline void list_splice_init(struct list_head *list,
175 struct list_head *head)
176 {
177 if (!list_empty(list)) {
178 __list_splice(list, head);
179 INIT_LIST_HEAD(list);
180 }
181 }
182
183 /**
184 * list_entry - get the struct for this entry
185 * @ptr: the &struct list_head pointer.
186 * @type: the type of the struct this is embedded in.
187 * @member: the name of the list_struct within the struct.
188 */
189 #define list_entry(ptr, type, member) \
190 ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
191
192 /**
193 * list_for_each - iterate over a list
194 * @pos: the &struct list_head to use as a loop counter.
195 * @head: the head for your list.
196 */
197 #define list_for_each(pos, head) \
198 for (pos = (head)->next; pos != (head); \
199 pos = pos->next)
200 /**
201 * list_for_each_prev - iterate over a list backwards
202 * @pos: the &struct list_head to use as a loop counter.
203 * @head: the head for your list.
204 */
205 #define list_for_each_prev(pos, head) \
206 for (pos = (head)->prev; pos != (head); \
207 pos = pos->prev)
208
209 /**
210 * list_for_each_safe - iterate over a list safe against removal of list entry
211 * @pos: the &struct list_head to use as a loop counter.
212 * @n: another &struct list_head to use as temporary storage
213 * @head: the head for your list.
214 */
215 #define list_for_each_safe(pos, n, head) \
216 for (pos = (head)->next, n = pos->next; pos != (head); \
217 pos = n, n = pos->next)
218
219 /**
220 * list_for_each_entry - iterate over list of given type
221 * @pos: the type * to use as a loop counter.
222 * @head: the head for your list.
223 * @member: the name of the list_struct within the struct.
224 */
225 #define list_for_each_entry(pos, head, member) \
226 for (pos = list_entry((head)->next, typeof(*pos), member); \
227 &pos->member != (head); \
228 pos = list_entry(pos->member.next, typeof(*pos), member))
229
230 /**
231 * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
232 * @pos: the type * to use as a loop counter.
233 * @n: another type * to use as temporary storage
234 * @head: the head for your list.
235 * @member: the name of the list_struct within the struct.
236 */
237 #define list_for_each_entry_safe(pos, n, head, member) \
238 for (pos = list_entry((head)->next, typeof(*pos), member), \
239 n = list_entry(pos->member.next, typeof(*pos), member); \
240 &pos->member != (head); \
241 pos = n, n = list_entry(n->member.next, typeof(*n), member))
242
243
244 #endif
245