FEATURES: Fix a typo and use uniform capitalization for list items.
[paraslash.git] / list.h
1 /*
2 * Copied from the Linux kernel source tree, version 2.6.13.
3 *
4 * Licensed under the GPL v2 as per the whole kernel source tree.
5 *
6 */
7
8 /** \file list.h doubly linked list implementation */
9
10 #include <stddef.h> /* offsetof */
11
12 /** get the struct this entry is embedded in */
13 #define container_of(ptr, type, member) ({ \
14 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
15 (type *)( (char *)__mptr - offsetof(type,member) );})
16
17 /**
18 * Non-NULL pointers that will result in page faults under normal
19 * circumstances, used to verify that nobody uses non-initialized list entries.
20 * Used for poisoning the \a next pointer of struct list_head.
21 */
22 #define LIST_POISON1 ((void *) 0x00100100)
23 /** Non-null pointer, used for poisoning the \a prev pointer of struct
24 * list_head
25 */
26 #define LIST_POISON2 ((void *) 0x00200200)
27
28 /** Simple doubly linked list implementation. */
29 struct list_head {
30 /** pointer to the next list entry */
31 struct list_head *next;
32 /** pointer to the previous list entry */
33 struct list_head *prev;
34 };
35
36 /** must be called before using any other list functions */
37 #define INIT_LIST_HEAD(ptr) do { \
38 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
39 } while (0)
40
41
42 /*
43 * Some of the internal functions ("__xxx") are useful when
44 * manipulating whole lists rather than single entries, as
45 * sometimes we already know the next/prev entries and we can
46 * generate better code by using them directly rather than
47 * using the generic single-entry routines.
48 */
49
50
51 /*
52 * Insert a new entry between two known consecutive entries.
53 *
54 * This is only for internal list manipulation where we know
55 * the prev/next entries already!
56 */
57 static inline void __list_add(struct list_head *new,
58 struct list_head *prev,
59 struct list_head *next)
60 {
61 next->prev = new;
62 new->next = next;
63 new->prev = prev;
64 prev->next = new;
65 }
66
67 /**
68 * add a new entry
69 *
70 * \param new new entry to be added
71 * \param 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 */
76 static inline void para_list_add(struct list_head *new, struct list_head *head)
77 {
78 __list_add(new, head, head->next);
79 }
80
81 /**
82 * add a new entry
83 *
84 * \param new new entry to be added
85 * \param 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 */
90 static inline void list_add_tail(struct list_head *new, struct list_head *head)
91 {
92 __list_add(new, head->prev, head);
93 }
94
95 /*
96 * Delete a list entry by making the prev/next entries
97 * point to each other.
98 *
99 * This is only for internal list manipulation where we know
100 * the prev/next entries already!
101 */
102 static inline void __list_del(struct list_head * prev, struct list_head * next)
103 {
104 next->prev = prev;
105 prev->next = next;
106 }
107
108 /**
109 * Delete entry from list.
110 *
111 * \param entry the element to delete from the list.
112 *
113 * Note: list_empty on entry does not return true after this, the entry is
114 * in an undefined state.
115 */
116 static inline void list_del(struct list_head *entry)
117 {
118 __list_del(entry->prev, entry->next);
119 entry->next = LIST_POISON1;
120 entry->prev = LIST_POISON2;
121 }
122
123 /**
124 * delete from one list and add as another's head
125 *
126 * \param list: the entry to move
127 * \param head: the head that will precede our entry
128 */
129 static inline void list_move(struct list_head *list, struct list_head *head)
130 {
131 __list_del(list->prev, list->next);
132 para_list_add(list, head);
133 }
134
135 /**
136 * test whether a list is empty
137 *
138 * \param head the list to test.
139 */
140 static inline int list_empty(const struct list_head *head)
141 {
142 return head->next == head;
143 }
144
145 /**
146 * get the struct for this entry
147 *
148 * \param ptr the &struct list_head pointer.
149 * \param type the type of the struct this is embedded in.
150 * \param member the name of the list_struct within the struct.
151 */
152 #define list_entry(ptr, type, member) \
153 container_of(ptr, type, member)
154
155 /**
156 * iterate over a list safe against removal of list entry
157 *
158 * \param pos the &struct list_head to use as a loop counter.
159 * \param n another &struct list_head to use as temporary storage
160 * \param head the head for your list.
161 */
162 #define list_for_each_safe(pos, n, head) \
163 for (pos = (head)->next, n = pos->next; pos != (head); \
164 pos = n, n = pos->next)
165
166 /**
167 * iterate over list of given type
168 *
169 * \param pos the type * to use as a loop counter.
170 * \param head the head for your list.
171 * \param member the name of the list_struct within the struct.
172 */
173 #define list_for_each_entry(pos, head, member) \
174 for (pos = list_entry((head)->next, typeof(*pos), member); \
175 &pos->member != (head); \
176 pos = list_entry(pos->member.next, typeof(*pos), member))
177
178 /**
179 * iterate over list of given type safe against removal of list entry
180 *
181 * \param pos the type * to use as a loop counter.
182 * \param n another type * to use as temporary storage
183 * \param head the head for your list.
184 * \param member the name of the list_struct within the struct.
185 */
186 #define list_for_each_entry_safe(pos, n, head, member) \
187 for (pos = list_entry((head)->next, typeof(*pos), member), \
188 n = list_entry(pos->member.next, typeof(*pos), member); \
189 &pos->member != (head); \
190 pos = n, n = list_entry(n->member.next, typeof(*n), member))
191 /**
192 * iterate backwards over list of given type safe against removal of list entry
193 * \param pos the type * to use as a loop counter.
194 * \param n another type * to use as temporary storage
195 * \param head the head for your list.
196 * \param member the name of the list_struct within the struct.
197 */
198 #define list_for_each_entry_safe_reverse(pos, n, head, member) \
199 for (pos = list_entry((head)->prev, typeof(*pos), member), \
200 n = list_entry(pos->member.prev, typeof(*pos), member); \
201 &pos->member != (head); \
202 pos = n, n = list_entry(n->member.prev, typeof(*n), member))