lib/list.h

   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  */
  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  */
  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  */
  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  */
  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  */
  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  */
 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  */
 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  */
 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  */
 137 static inline int list_empty(struct list_head *head)
 138 {
 139         return head->next == head;
 140 }
 141
 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  */
 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  */
 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