list.h: Rename argument of list_move().
[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 /** \file list.h Doubly linked list implementation. */
8
9 #include <stddef.h> /* offsetof */
10
11 /** Get the struct this entry is embedded in. */
12 #define container_of(ptr, type, member) ({ \
13 const typeof( ((type *)0)->member ) *__mptr = (ptr); \
14 (type *)( (char *)__mptr - offsetof(type,member) );})
15
16 /** A list head is just a pair of pointers. */
17 struct list_head {
18 /** Pointer to the next list entry. */
19 struct list_head *next;
20 /** Pointer to the previous list entry. */
21 struct list_head *prev;
22 };
23
24 /** Define an initialized list head. */
25 #define INITIALIZED_LIST_HEAD(name) struct list_head name = {&(name), &(name)}
26
27 /** This must be called before using any other list functions. */
28 #define INIT_LIST_HEAD(ptr) do { \
29 (ptr)->next = (ptr); (ptr)->prev = (ptr); \
30 } while (0)
31
32 /**
33 * Insert a new entry after the specified head.
34 *
35 * \param entry The new entry to add.
36 * \param head The list head to add it after.
37 *
38 * This is good for implementing stacks.
39 */
40 static inline void para_list_add(struct list_head *entry, struct list_head *head)
41 {
42 entry->prev = head;
43 entry->next = head->next;
44 head->next->prev = entry;
45 head->next = entry;
46 }
47
48 /**
49 * Insert a new entry before the specified head.
50 *
51 * \param entry The new entry to add.
52 * \param head list head to add it before.
53 *
54 * This is useful for implementing queues.
55 */
56 static inline void list_add_tail(struct list_head *entry, struct list_head *head)
57 {
58 entry->prev = head->prev;
59 entry->next = head;
60 head->prev->next = entry;
61 head->prev = entry;
62 }
63
64 /**
65 * Delete an entry from a list.
66 *
67 * \param entry The element to delete.
68 *
69 * The list entry is in an undefined state after this and \ref list_empty()
70 * does not return true.
71 */
72 static inline void list_del(struct list_head *entry)
73 {
74 entry->prev->next = entry->next;
75 entry->next->prev = entry->prev;
76 /*
77 * These non-NULL pointers result in page faults when dereferenced.
78 * This helps to catch bugs resulting from using deleted list heads.
79 */
80 entry->next = (void *)0x00100100;
81 entry->prev = (void *)0x00200200;
82 }
83
84 /**
85 * Delete an entry from one list and add it as another list's head.
86 *
87 * \param entry The entry to move.
88 * \param head The head that will precede our entry.
89 */
90 static inline void list_move(struct list_head *entry, struct list_head *head)
91 {
92 list_del(entry);
93 para_list_add(entry, head);
94 }
95
96 /**
97 * Test whether a list contains no entries.
98 *
99 * \param head The list to test.
100 */
101 static inline int list_empty(const struct list_head *head)
102 {
103 return head->next == head;
104 }
105
106 /**
107 * Get the struct in which this entry is embedded in.
108 *
109 * \param ptr The list head pointer.
110 * \param type The type of containing structure.
111 * \param member The name of the list head member within the structure.
112 */
113 #define list_entry(ptr, type, member) container_of(ptr, type, member)
114
115 /**
116 * Iterate over a list.
117 *
118 * \param pos A list head pointer which serves as the iterator.
119 * \param head The head of the list.
120 * \param member The name of the list head member within the structure.
121 */
122 #define list_for_each_entry(pos, head, member) \
123 for (pos = list_entry((head)->next, typeof(*pos), member); \
124 &pos->member != (head); \
125 pos = list_entry(pos->member.next, typeof(*pos), member))
126
127 /**
128 * Iterate over list, safe against removal of list entry.
129 *
130 * \param pos The iterator.
131 * \param n A list head pointer which is used as temporary storage.
132 * \param head The head of the list.
133 * \param member The name of the list head member within the structure.
134 */
135 #define list_for_each_entry_safe(pos, n, head, member) \
136 for (pos = list_entry((head)->next, typeof(*pos), member), \
137 n = list_entry(pos->member.next, typeof(*pos), member); \
138 &pos->member != (head); \
139 pos = n, n = list_entry(n->member.next, typeof(*n), member))
140
141 /**
142 * Get the first element of a list.
143 *
144 * \param ptr The list head to take the element from.
145 * \param type The type of the struct this is embedded in.
146 * \param member The name of the list_struct within the struct.
147 *
148 * Note that the list is expected to be non-empty.
149 */
150 #define list_first_entry(ptr, type, member) \
151 list_entry((ptr)->next, type, member)
152
153 /**
154 * Test whether a list has just one entry.
155 *
156 * \param head The list to test.
157 */
158 static inline int list_is_singular(const struct list_head *head)
159 {
160 return !list_empty(head) && (head->next == head->prev);
161 }