include/list.h

   1 /*
   2  * Copyright (c) 2006 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #ifndef __LIST_H__
  19 #define __LIST_H__
  20
  21 /*
  22  * This undef is here because BSD 4.4 added some LIST_ macros into system
  23  * header file sys/queue.h. This header is included in many other system
  24  * headers and thus causes "macro redefined" warnings.
  25  *
  26  * As OS X is kind of a derivate of BSD, this affects OS X too.
  27  *
  28  * To use our own LIST_ macros (copied from kernel code), we have to
  29  * at first undefine the conflicting system macros.
  30  *
  31  */
  32 #undef LIST_HEAD
  33 #undef LIST_HEAD_INIT
  34
  35 /*
  36  * Simple, generic doubly-linked list implementation.
  37  */
  38
  39 struct list_head {
  40         struct list_head *next;
  41         struct list_head *prev;
  42 };
  43
  44 #define LIST_HEAD_INIT(name) { &(name), &(name) }
  45
  46 #define LIST_HEAD(name) \
  47                 struct list_head name = LIST_HEAD_INIT(name)
  48
  49 #define INIT_LIST_HEAD(list) list_head_init(list)
  50 static inline void list_head_init(struct list_head *list)
  51 {
  52         list->next = list->prev = list;
  53 }
  54
  55 static inline void list_head_destroy(struct list_head *list)
  56 {
  57         list->next = list->prev = NULL;
  58 }
  59
  60 static inline void __list_add(struct list_head *add,
  61                               struct list_head *prev, struct list_head *next)
  62 {
  63         next->prev = add;
  64         add->next = next;
  65         add->prev = prev;
  66         prev->next = add;
  67 }
  68
  69 static inline void list_add(struct list_head *add, struct list_head *head)
  70 {
  71         __list_add(add, head, head->next);
  72 }
  73
  74 static inline void list_add_tail(struct list_head *add, struct list_head *head)
  75 {
  76         __list_add(add, head->prev, head);
  77 }
  78
  79 static inline void __list_del(struct list_head *prev, struct list_head *next)
  80 {
  81         next->prev = prev;
  82         prev->next = next;
  83 }
  84
  85 static inline void list_del_init(struct list_head *entry)
  86 {
  87         __list_del(entry->prev, entry->next);
  88         list_head_init(entry);
  89 }
  90
  91 static inline void list_del(struct list_head *entry)
  92 {
  93         __list_del(entry->prev, entry->next);
  94 }
  95
  96 static inline void list_move(struct list_head *list, struct list_head *head)
  97 {
  98         __list_del(list->prev, list->next);
  99         list_add(list, head);
 100 }
 101
 102 static inline void list_move_tail(struct list_head *list, struct list_head *head)
 103 {
 104         __list_del(list->prev, list->next);
 105         list_add_tail(list, head);
 106 }
 107
 108 static inline int list_empty(const struct list_head *head)
 109 {
 110         return head->next == head;
 111 }
 112
 113 static inline void __list_splice(struct list_head *list,
 114                                  struct list_head *prev,
 115                                  struct list_head *next)
 116 {
 117         struct list_head *first = list->next;
 118         struct list_head *last = list->prev;
 119
 120         first->prev = prev;
 121         prev->next = first;
 122
 123         last->next = next;
 124         next->prev = last;
 125 }
 126
 127 static inline void list_splice(struct list_head *list, struct list_head *head)
 128 {
 129         if (!list_empty(list))
 130                 __list_splice(list, head, head->next);
 131 }
 132
 133 static inline void list_splice_init(struct list_head *list,
 134                                     struct list_head *head)
 135 {
 136         if (!list_empty(list)) {
 137                 __list_splice(list, head, head->next);
 138                 list_head_init(list);
 139         }
 140 }
 141
 142 #define list_entry(ptr, type, member) ({                        \
 143         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 144         (type *)( (char *)__mptr - offsetof(type,member) );})
 145
 146 #define list_for_each(pos, head) \
 147         for (pos = (head)->next; pos != (head); pos = pos->next)
 148
 149 #define list_for_each_safe(pos, n, head) \
 150         for (pos = (head)->next, n = pos->next; pos != (head); \
 151                 pos = n, n = pos->next)
 152
 153 #define list_for_each_entry(pos, head, member)                          \
 154         for (pos = list_entry((head)->next, typeof(*pos), member);      \
 155              &pos->member != (head);    \
 156              pos = list_entry(pos->member.next, typeof(*pos), member))
 157
 158 #define list_for_each_entry_safe(pos, n, head, member)                  \
 159         for (pos = list_entry((head)->next, typeof(*pos), member),      \
 160                 n = list_entry(pos->member.next, typeof(*pos), member); \
 161              &pos->member != (head);                                    \
 162              pos = n, n = list_entry(n->member.next, typeof(*n), member))
 163
 164 #define list_first_entry(ptr, type, member) \
 165         list_entry((ptr)->next, type, member)
 166
 167 #define container_of(ptr, type, member) ({                      \
 168         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
 169         (type *)( (char *)__mptr - offsetof(type,member) );})
 170
 171 void list_sort(void *priv, struct list_head *head,
 172                int (*cmp)(void *priv, struct list_head *a,
 173                           struct list_head *b));
 174
 175 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
 176
 177 /**
 178  * list_splice_tail_init - join two lists and reinitialise the emptied list
 179  * @list: the new list to add.
 180  * @head: the place to add it in the first list.
 181  *
 182  * Each of the lists is a queue.
 183  * The list at @list is reinitialised
 184  */
 185 static inline void list_splice_tail_init(struct list_head *list,
 186                                          struct list_head *head)
 187 {
 188         if (!list_empty(list)) {
 189                 __list_splice(list, head->prev, head);
 190                 INIT_LIST_HEAD(list);
 191         }
 192 }
 193
 194 /**
 195  * list_last_entry - get the last element from a list
 196  * @ptr:        the list head to take the element from.
 197  * @type:       the type of the struct this is embedded in.
 198  * @member:     the name of the list_head within the struct.
 199  *
 200  * Note, that list is expected to be not empty.
 201  */
 202 #define list_last_entry(ptr, type, member) \
 203         list_entry((ptr)->prev, type, member)
 204
 205 /**
 206  * list_prev_entry - get the prev element in list
 207  * @pos:        the type * to cursor
 208  * @member:     the name of the list_head within the struct.
 209  */
 210 #define list_prev_entry(pos, member) \
 211         list_entry((pos)->member.prev, typeof(*(pos)), member)
 212
 213 /**
 214  * list_for_each_entry_reverse - iterate backwards over list of given type.
 215  * @pos:        the type * to use as a loop cursor.
 216  * @head:       the head for your list.
 217  * @member:     the name of the list_head within the struct.
 218  */
 219 #define list_for_each_entry_reverse(pos, head, member)                  \
 220         for (pos = list_last_entry(head, typeof(*pos), member);         \
 221              &pos->member != (head);                                    \
 222              pos = list_prev_entry(pos, member))
 223
 224 #endif  /* __LIST_H__ */