list.h

/*
 * Doubly-linked list
 * Copyright (c) 2009, Jouni Malinen <j@w1.fi>
 *
 * This software may be distributed under the terms of the BSD license.
 * See README for more details.
 */

#ifndef LIST_H
#define LIST_H

struct dl_list {
    struct dl_list *next;
    struct dl_list *prev;
};

#define DL_LIST_HEAD_INIT(l) { &(l), &(l) }

static inline void dl_list_init(struct dl_list *list)
{
    list->next = list;
    list->prev = list;
}

static inline void dl_list_add(struct dl_list *list, struct dl_list *item)
{
    item->next = list->next;
    item->prev = list;
    list->next->prev = item;
    list->next = item;
}

static inline void dl_list_add_tail(struct dl_list *list, struct dl_list *item)
{
    dl_list_add(list->prev, item);
}

static inline void dl_list_del(struct dl_list *item)
{
    item->next->prev = item->prev;
    item->prev->next = item->next;
    item->next = NULL;
    item->prev = NULL;
}

static inline int dl_list_empty(struct dl_list *list)
{
    return list->next == list;
}

static inline unsigned int dl_list_len(struct dl_list *list)
{
    struct dl_list *item;
    int count = 0;
    for (item = list->next; item != list; item = item->next)
        count++;
    return count;
}

#ifndef offsetof
#define offsetof(type, member) ((long) &((type *) 0)->member)
#endif

#define dl_list_entry(item, type, member) \
    ((type *) ((char *) item - offsetof(type, member)))

#define dl_list_first(list, type, member) \
    (dl_list_empty((list)) ? NULL : \
     dl_list_entry((list)->next, type, member))

#define dl_list_last(list, type, member) \
    (dl_list_empty((list)) ? NULL : \
     dl_list_entry((list)->prev, type, member))

#define dl_list_for_each(item, list, type, member) \
    for (item = dl_list_entry((list)->next, type, member); \
         &item->member != (list); \
         item = dl_list_entry(item->member.next, type, member))

#define dl_list_for_each_safe(item, n, list, type, member) \
    for (item = dl_list_entry((list)->next, type, member), \
             n = dl_list_entry(item->member.next, type, member); \
         &item->member != (list); \
         item = n, n = dl_list_entry(n->member.next, type, member))

#define dl_list_for_each_reverse(item, list, type, member) \
    for (item = dl_list_entry((list)->prev, type, member); \
         &item->member != (list); \
         item = dl_list_entry(item->member.prev, type, member))

#define DEFINE_DL_LIST(name) \
    struct dl_list name = { &(name), &(name) }

#endif /* LIST_H */