op_list.h

Go to the documentation of this file.

#ifndef OP_LIST_H
#define OP_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;
};

static __inline__ void list_init(struct list_head * ptr)
{
    ptr->next = ptr;
    ptr->prev = ptr;
}

/*
 * 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_entry,
    struct list_head * prev,
    struct list_head * next)
{
    next->prev = new_entry;
    new_entry->next = next;
    new_entry->prev = prev;
    prev->next = new_entry;
}

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

static __inline__ void list_add_tail(struct list_head * new_entry, struct list_head * head)
{
    __list_add(new_entry, 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);
}

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

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

static __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;
    }
}

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

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

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

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

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

#endif /* OP_LIST_H */