list.h

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  #ifndef _LINUX_LIST_H
  #define _LINUX_LIST_H


  /*
   * Simple doubly linked list implementation.
   *
   * Some of the internal functions ("__xxx") are useful when
   * manipulating whole lists rather than single entries, as
   * sometimes we already know the next/prev entries and we can
   * generate better code by using them directly rather than
   * using the generic single-entry routines.
   */

  struct list_head {
          struct list_head *next, *prev;
  };

  #define LIST_HEAD_INIT(name) { &(name), &(name) }

  #define LIST_HEAD(name) \
          struct list_head name = LIST_HEAD_INIT(name)

  #define INIT_LIST_HEAD(ptr) do { \
          (ptr)->next = (ptr); (ptr)->prev = (ptr); \
  } while (0)


  /*
   * Insert a new entry between two known consecutive entries.
   *
   * This is only for internal list manipulation where we know
   * the prev/next entries already!
   */
  static inline void __list_add(struct list_head *new,
                                struct list_head *prev,
                                struct list_head *next)
  {
          next->prev = new;
          new->next = next;
          new->prev = prev;
          prev->next = new;
  }

  static inline void list_add(struct list_head *new, struct list_head *head)
  {
         __list_add(new, head, head->next);
  }

  static inline void list_add_tail(struct list_head *new, struct list_head *head)
  {
          __list_add(new, head->prev, head);
  }

  /*
   * Delete a list entry by making the prev/next entries
   * point to each other.
   *
   * This is only for internal list manipulation where we know
   * the prev/next entries already!
   */
  static inline void __list_del(struct list_head *prev, struct list_head *next)
  {
          next->prev = prev;
          prev->next = next;
  }

  static inline void list_del(struct list_head *entry)
  {
          __list_del(entry->prev, entry->next);
          entry->next = (void *) 0;
          entry->prev = (void *) 0;
  }

 static inline void list_del_init(struct list_head *entry)
 {
         __list_del(entry->prev, entry->next);
         INIT_LIST_HEAD(entry);
 }

 static inline void list_move(struct list_head *list, struct list_head *head)
 {
         __list_del(list->prev, list->next);
         list_add(list, head);
 }

 static inline void list_move_tail(struct list_head *list,
                                   struct list_head *head)
 {
         __list_del(list->prev, list->next);
         list_add_tail(list, head);
 }

 static inline int list_empty(struct list_head *head)
 {
         return head->next == head;
 }

 static inline void __list_splice(struct list_head *list,
                                  struct list_head *head)
 {
         struct list_head *first = list->next;
         struct list_head *last = list->prev;
         struct list_head *at = head->next;

         first->prev = head;
         head->next = first;

         last->next = at;
         at->prev = last;
 }

 static inline void list_splice(struct list_head *list, struct list_head *head)
 {
         if (!list_empty(list))
                 __list_splice(list, head);
 }

 static inline void list_splice_init(struct list_head *list,
                                     struct list_head *head)
 {
         if (!list_empty(list)) {
                 __list_splice(list, head);
                 INIT_LIST_HEAD(list);
         }
 }

 #define list_entry(ptr, type, member) \
         ((type *)((char *)(ptr)-(uintptr_t)(&((type *)0)->member)))

 #define list_for_each(pos, head) \
         for (pos = (head)->next; pos != (head); \
                 pos = pos->next)

 #define list_for_each_prev(pos, head) \
         for (pos = (head)->prev; pos != (head); \
                 pos = pos->prev)

 #define list_for_each_safe(pos, n, head) \
         for (pos = (head)->next, n = pos->next; pos != (head); \
                 pos = n, n = pos->next)

 #define list_for_each_entry(pos, head, member)                          \
         for (pos = list_entry((head)->next, typeof(*pos), member);      \
              &pos->member != (head);                                    \
              pos = list_entry(pos->member.next, typeof(*pos), member))

 #define list_for_each_entry_safe(pos, n, head, member)                  \
         for (pos = list_entry((head)->next, typeof(*pos), member),      \
                 n = list_entry(pos->member.next, typeof(*pos), member); \
              &pos->member != (head);                                    \
              pos = n, n = list_entry(n->member.next, typeof(*n), member))

 #define list_for_each_entry_continue(pos, head, member)                 \
         for (pos = list_entry(pos->member.next, typeof(*pos), member);  \
              &pos->member != (head);                                    \
              pos = list_entry(pos->member.next, typeof(*pos), member))

 #endif