#ifndef LIST_H
#define LIST_H

/* Doubly linked lists */
typedef struct link_t link_t;
struct link_t
{
    link_t *next;
    link_t *prev;
};

typedef struct list_t list_t;
struct list_t
{
    link_t *head;
    link_t *tail;
};

static inline void
list_init (list_t *list)
{
    list->head = (link_t *)list;
    list->tail = (link_t *)list;
}

static inline void
list_prepend (list_t *list, link_t *link)
{
    link->next = list->head;
    link->prev = (link_t *)list;
    list->head->prev = link;
    list->head = link;
}

static inline void
list_append (list_t *list, link_t *link)
{
    link->prev = list->tail;
    link->next = (link_t *)list;
    list->tail->next = link;
    list->tail = link;
}

static inline void
list_unlink (link_t *link)
{
    link->prev->next = link->next;
    link->next->prev = link->prev;
}

static inline int
list_is_empty (list_t *list)
{
    return list->head == (link_t *)list;
}

static inline void
list_move_to_front (list_t *list, link_t *link)
{
    list_unlink (link);
    list_prepend (list, link);
}

#define LIST_FOREACH(list, link)					\
    for ((link) = (list)->head;						\
	 (link) != (link_t *)(list);					\
	 (link) = (link)->next)

#if defined(__GNUC__) && __GNUC__ >= 4
#   define OFFSET_OF(type, member)					\
    ((unsigned long)__builtin_offsetof(type, member))
#else
#   define OFFSET_OF(type, member)					\
    ((unsigned long)(&(((type *)0)->member))
#endif

#define CONTAINER_OF(type, member, data)				\
    ((type *)(((uint8_t *)data) - OFFSET_OF(type, member)))

#endif