1 #ifndef _LIST_H
2 #define _LIST_H 1
3
4 /*
5 * Simple doubly linked list implementation.
6 * -- shameless stolen from the linux kernel sources
7 *
8 * Some of the internal functions ("__xxx") are useful when
9 * manipulating whole lists rather than single entries, as
10 * sometimes we already know the next/prev entries and we can
11 * generate better code by using them directly rather than
12 * using the generic single-entry routines.
13 */
14
15 struct list_head {
16 struct list_head *next, *prev;
17 };
18
19 #define LIST_HEAD_INIT(name) { &(name), &(name) }
20
21 #define LIST_HEAD(name) \
22 struct list_head name = LIST_HEAD_INIT(name)
23
24 #define INIT_LIST_HEAD(ptr) do { \
25 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
26 } while (0)
27
28 /*
29 * Insert a new entry between two known consecutive entries.
30 *
31 * This is only for internal list manipulation where we know
32 * the prev/next entries already!
33 */
34 static __inline__ void __list_add(struct list_head * new,
35 struct list_head * prev,
36 struct list_head * next)
37 {
38 next->prev = new;
39 new->next = next;
40 new->prev = prev;
41 prev->next = new;
42 }
43
44 /**
45 * list_add - add a new entry
46 * @new: new entry to be added
47 * @head: list head to add it after
48 *
49 * Insert a new entry after the specified head.
50 * This is good for implementing stacks.
51 */
52 static __inline__ void list_add(struct list_head *new, struct list_head *head)
53 {
54 __list_add(new, head, head->next);
55 }
56
57 /**
58 * list_add_tail - add a new entry
59 * @new: new entry to be added
60 * @head: list head to add it before
61 *
62 * Insert a new entry before the specified head.
63 * This is useful for implementing queues.
64 */
65 static __inline__ void list_add_tail(struct list_head *new, struct list_head *head)
66 {
67 __list_add(new, head->prev, head);
68 }
69
70 /*
71 * Delete a list entry by making the prev/next entries
72 * point to each other.
73 *
74 * This is only for internal list manipulation where we know
75 * the prev/next entries already!
76 */
77 static __inline__ void __list_del(struct list_head * prev,
78 struct list_head * next)
79 {
80 next->prev = prev;
81 prev->next = next;
82 }
83
84 /**
85 * list_del - deletes entry from list.
86 * @entry: the element to delete from the list.
87 * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
88 */
89 static __inline__ void list_del(struct list_head *entry)
90 {
91 __list_del(entry->prev, entry->next);
92 }
93
94 /**
95 * list_del_init - deletes entry from list and reinitialize it.
96 * @entry: the element to delete from the list.
97 */
98 static __inline__ void list_del_init(struct list_head *entry)
99 {
100 __list_del(entry->prev, entry->next);
101 INIT_LIST_HEAD(entry);
102 }
103
104 /**
105 * list_empty - tests whether a list is empty
106 * @head: the list to test.
107 */
108 static __inline__ int list_empty(struct list_head *head)
109 {
110 return head->next == head;
111 }
112
113 /**
114 * list_splice - join two lists
115 * @list: the new list to add.
116 * @head: the place to add it in the first list.
117 */
118 static __inline__ void list_splice(struct list_head *list, struct list_head *head)
119 {
120 struct list_head *first = list->next;
121
122 if (first != list) {
123 struct list_head *last = list->prev;
124 struct list_head *at = head->next;
125
126 first->prev = head;
127 head->next = first;
128
129 last->next = at;
130 at->prev = last;
131 }
132 }
133
134 /**
135 * list_entry - get the struct for this entry
136 * @ptr: the &struct list_head pointer.
137 * @type: the type of the struct this is embedded in.
138 * @member: the name of the list_struct within the struct.
139 */
140 #define list_entry(ptr, type, member) \
141 ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
142
143 /**
144 * list_for_each - iterate over a list
145 * @pos: the &struct list_head to use as a loop counter.
146 * @head: the head for your list.
147 */
148 #define list_for_each(pos, head) \
149 for (pos = (head)->next; pos != (head); pos = pos->next)
150
151 /**
152 * list_for_each_safe - iterate over a list safe against removal of list entry
153 * @pos: the &struct list_head to use as a loop counter.
154 * @n: another &struct list_head to use as temporary storage
155 * @head: the head for your list.
156 */
157 #define list_for_each_safe(pos, n, head) \
158 for (pos = (head)->next, n = pos->next; pos != (head); \
159 pos = n, n = pos->next)
160
161 /**
162 * list_for_each_prev - iterate over a list in reverse order
163 * @pos: the &struct list_head to use as a loop counter.
164 * @head: the head for your list.
165 */
166 #define list_for_each_prev(pos, head) \
167 for (pos = (head)->prev; pos != (head); pos = pos->prev)
168
169 #endif /* _LIST_H */
170
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