source: MondoRescue/branches/stable/mindi-busybox/e2fsprogs/blkid/list.h@ 821

#if !defined(_BLKID_LIST_H) && !defined(LIST_HEAD)
#define _BLKID_LIST_H

#ifdef __cplusplus
extern "C" {
#endif

#ifdef __GNUC__
#define _INLINE_ static __inline__
#else                         /* For Watcom C */
#define _INLINE_ static inline
#endif

/*
 * 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!
 */
_INLINE_ void __list_add(struct list_head * add,
    struct list_head * prev,
    struct list_head * next)
{
    next->prev = add;
    add->next = next;
    add->prev = prev;
    prev->next = add;
}

/**
 * list_add - add a new entry
 * @add:    new entry to be added
 * @head:   list head to add it after
 *
 * Insert a new entry after the specified head.
 * This is good for implementing stacks.
 */
_INLINE_ void list_add(struct list_head *add, struct list_head *head)
{
    __list_add(add, head, head->next);
}

/**
 * list_add_tail - add a new entry
 * @add:    new entry to be added
 * @head:   list head to add it before
 *
 * Insert a new entry before the specified head.
 * This is useful for implementing queues.
 */
_INLINE_ void list_add_tail(struct list_head *add, struct list_head *head)
{
    __list_add(add, 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!
 */
_INLINE_ void __list_del(struct list_head * prev,
                  struct list_head * next)
{
    next->prev = prev;
    prev->next = next;
}

/**
 * list_del - deletes entry from list.
 * @entry:  the element to delete from the list.
 *
 * list_empty() on @entry does not return true after this, @entry is
 * in an undefined state.
 */
_INLINE_ void list_del(struct list_head *entry)
{
    __list_del(entry->prev, entry->next);
}

/**
 * list_del_init - deletes entry from list and reinitialize it.
 * @entry:  the element to delete from the list.
 */
_INLINE_ void list_del_init(struct list_head *entry)
{
    __list_del(entry->prev, entry->next);
    INIT_LIST_HEAD(entry);
}

/**
 * list_empty - tests whether a list is empty
 * @head:   the list to test.
 */
_INLINE_ int list_empty(struct list_head *head)
{
    return head->next == head;
}

/**
 * list_splice - join two lists
 * @list:   the new list to add.
 * @head:   the place to add it in the first list.
 */
_INLINE_ void list_splice(struct list_head *list, struct list_head *head)
{
    struct list_head *first = list->next;

    if (first != list) {
        struct list_head *last = list->prev;
        struct list_head *at = head->next;

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

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

/**
 * list_entry - get the struct for this entry
 * @ptr:    the &struct list_head pointer.
 * @type:   the type of the struct this is embedded in.
 * @member: the name of the list_struct within the struct.
 */
#define list_entry(ptr, type, member) \
    ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

/**
 * list_for_each - iterate over elements in a list
 * @pos:    the &struct list_head to use as a loop counter.
 * @head:   the head for your list.
 */
#define list_for_each(pos, head) \
    for (pos = (head)->next; pos != (head); pos = pos->next)

/**
 * list_for_each_safe - iterate over elements in a list, but don't dereference
 *                      pos after the body is done (in case it is freed)
 * @pos:    the &struct list_head to use as a loop counter.
 * @pnext:  the &struct list_head to use as a pointer to the next item.
 * @head:   the head for your list (not included in iteration).
 */
#define list_for_each_safe(pos, pnext, head) \
    for (pos = (head)->next, pnext = pos->next; pos != (head); \
         pos = pnext, pnext = pos->next)

#undef _INLINE_

#ifdef __cplusplus
}
#endif

#endif /* _BLKID_LIST_H */