LXR linux-old/include/linux/list.h

   1#ifndef _LINUX_LIST_H
   2#define _LINUX_LIST_H
   3
   4#ifdef __KERNEL__
   5
   6/*
   7 * Simple doubly linked list implementation.
   8 *
   9 * Some of the internal functions ("__xxx") are useful when
  10 * manipulating whole lists rather than single entries, as
  11 * sometimes we already know the next/prev entries and we can
  12 * generate better code by using them directly rather than
  13 * using the generic single-entry routines.
  14 */
  15
  16struct list_head {
  17        struct list_head *next, *prev;
  18};
  19
  20#define LIST_HEAD_INIT(name) { &(name), &(name) }
  21
  22#define LIST_HEAD(name) \
  23        struct list_head name = LIST_HEAD_INIT(name)
  24
  25#define INIT_LIST_HEAD(ptr) do { \
  26        (ptr)->next = (ptr); (ptr)->prev = (ptr); \
  27} while (0)
  28
  29/*
  30 * Insert a new entry between two known consecutive entries. 
  31 *
  32 * This is only for internal list manipulation where we know
  33 * the prev/next entries already!
  34 */
  35static __inline__ void __list_add(struct list_head * new,
  36        struct list_head * prev,
  37        struct list_head * next)
  38{
  39        next->prev = new;
  40        new->next = next;
  41        new->prev = prev;
  42        prev->next = new;
  43}
  44
  45/**
  46 * list_add - add a new entry
  47 * @new: new entry to be added
  48 * @head: list head to add it after
  49 *
  50 * Insert a new entry after the specified head.
  51 * This is good for implementing stacks.
  52 */
  53static __inline__ void list_add(struct list_head *new, struct list_head *head)
  54{
  55        __list_add(new, head, head->next);
  56}
  57
  58/**
  59 * list_add_tail - add a new entry
  60 * @new: new entry to be added
  61 * @head: list head to add it before
  62 *
  63 * Insert a new entry before the specified head.
  64 * This is useful for implementing queues.
  65 */
  66static __inline__ void list_add_tail(struct list_head *new, struct list_head *head)
  67{
  68        __list_add(new, head->prev, head);
  69}
  70
  71/*
  72 * Delete a list entry by making the prev/next entries
  73 * point to each other.
  74 *
  75 * This is only for internal list manipulation where we know
  76 * the prev/next entries already!
  77 */
  78static __inline__ void __list_del(struct list_head * prev,
  79                                  struct list_head * next)
  80{
  81        next->prev = prev;
  82        prev->next = next;
  83}
  84
  85/**
  86 * list_del - deletes entry from list.
  87 * @entry: the element to delete from the list.
  88 * Note: list_empty on entry does not return true after this, the entry is in an undefined state.
  89 */
  90static __inline__ void list_del(struct list_head *entry)
  91{
  92        __list_del(entry->prev, entry->next);
  93}
  94
  95/**
  96 * list_del_init - deletes entry from list and reinitialize it.
  97 * @entry: the element to delete from the list.
  98 */
  99static __inline__ void list_del_init(struct list_head *entry)
 100{
 101        __list_del(entry->prev, entry->next);
 102        INIT_LIST_HEAD(entry); 
 103}
 104
 105/**
 106 * list_empty - tests whether a list is empty
 107 * @head: the list to test.
 108 */
 109static __inline__ int list_empty(struct list_head *head)
 110{
 111        return head->next == head;
 112}
 113
 114/**
 115 * list_splice - join two lists
 116 * @list: the new list to add.
 117 * @head: the place to add it in the first list.
 118 */
 119static __inline__ void list_splice(struct list_head *list, struct list_head *head)
 120{
 121        struct list_head *first = list->next;
 122
 123        if (first != list) {
 124                struct list_head *last = list->prev;
 125                struct list_head *at = head->next;
 126
 127                first->prev = head;
 128                head->next = first;
 129
 130                last->next = at;
 131                at->prev = last;
 132        }
 133}
 134
 135/**
 136 * list_entry - get the struct for this entry
 137 * @ptr:        the &struct list_head pointer.
 138 * @type:       the type of the struct this is embedded in.
 139 * @member:     the name of the list_struct within the struct.
 140 */
 141#define list_entry(ptr, type, member) \
 142        ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
 143
 144/**
 145 * list_for_each        -       iterate over a list
 146 * @pos:        the &struct list_head to use as a loop counter.
 147 * @head:       the head for your list.
 148 */
 149#define list_for_each(pos, head) \
 150        for (pos = (head)->next; pos != (head); pos = pos->next)
 151
 152#endif /* __KERNEL__ */
 153
 154#endif
 155