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   1/*
   2 * Copyright (C) 2002 Free Software Foundation, Inc.
   3 * (originally part of the GNU C Library and Userspace RCU)
   4 * Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   5 *
   6 * Copyright (C) 2009 Pierre-Marc Fournier
   7 * Conversion to RCU list.
   8 * Copyright (C) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   9 *
  10 * This library is free software; you can redistribute it and/or
  11 * modify it under the terms of the GNU Lesser General Public
  12 * License as published by the Free Software Foundation; either
  13 * version 2.1 of the License, or (at your option) any later version.
  14 *
  15 * This library is distributed in the hope that it will be useful,
  16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  18 * Lesser General Public License for more details.
  19 *
  20 * You should have received a copy of the GNU Lesser General Public
  21 * License along with this library; if not, see
  22 * <http://www.gnu.org/licenses/>.
  23 */
  24
  25#ifndef LIST_H
  26#define LIST_H  1
  27
  28/*
  29 * The definitions of this file are adopted from those which can be
  30 * found in the Linux kernel headers to enable people familiar with the
  31 * latter find their way in these sources as well.
  32 */
  33
  34/* Basic type for the double-link list. */
  35struct list_head {
  36        struct list_head *next, *prev;
  37};
  38
  39/* avoid conflicts with BSD-only sys/queue.h */
  40#undef LIST_HEAD
  41/* Define a variable with the head and tail of the list. */
  42#define LIST_HEAD(name) \
  43        struct list_head name = { &(name), &(name) }
  44
  45/* Initialize a new list head. */
  46#define INIT_LIST_HEAD(ptr) \
  47        (ptr)->next = (ptr)->prev = (ptr)
  48
  49#define LIST_HEAD_INIT(name) { &(name), &(name) }
  50
  51/* Add new element at the head of the list. */
  52static inline void list_add(struct list_head *newp, struct list_head *head)
  53{
  54        head->next->prev = newp;
  55        newp->next = head->next;
  56        newp->prev = head;
  57        head->next = newp;
  58}
  59
  60/* Add new element at the tail of the list. */
  61static inline void list_add_tail(struct list_head *newp, struct list_head *head)
  62{
  63        head->prev->next = newp;
  64        newp->next = head;
  65        newp->prev = head->prev;
  66        head->prev = newp;
  67}
  68
  69/* Remove element from list. */
  70static inline void __list_del(struct list_head *prev, struct list_head *next)
  71{
  72        next->prev = prev;
  73        prev->next = next;
  74}
  75
  76/* Remove element from list. */
  77static inline void list_del(struct list_head *elem)
  78{
  79        __list_del(elem->prev, elem->next);
  80}
  81
  82/* Remove element from list, initializing the element's list pointers. */
  83static inline void list_del_init(struct list_head *elem)
  84{
  85        list_del(elem);
  86        INIT_LIST_HEAD(elem);
  87}
  88
  89/* Delete from list, add to another list as head. */
  90static inline void list_move(struct list_head *elem, struct list_head *head)
  91{
  92        __list_del(elem->prev, elem->next);
  93        list_add(elem, head);
  94}
  95
  96/* Replace an old entry. */
  97static inline void list_replace(struct list_head *old, struct list_head *newp)
  98{
  99        newp->next = old->next;
 100        newp->prev = old->prev;
 101        newp->prev->next = newp;
 102        newp->next->prev = newp;
 103}
 104
 105/* Join two lists. */
 106static inline void list_splice(struct list_head *add, struct list_head *head)
 107{
 108        /* Do nothing if the list which gets added is empty. */
 109        if (add != add->next) {
 110                add->next->prev = head;
 111                add->prev->next = head->next;
 112                head->next->prev = add->prev;
 113                head->next = add->next;
 114        }
 115}
 116
 117/* Get typed element from list at a given position. */
 118#define list_entry(ptr, type, member) \
 119        ((type *) ((char *) (ptr) - offsetof(type, member)))
 120
 121/* Get first entry from a list. */
 122#define list_first_entry(ptr, type, member) \
 123        list_entry((ptr)->next, type, member)
 124
 125/* Iterate forward over the elements of the list. */
 126#define list_for_each(pos, head) \
 127        for (pos = (head)->next; pos != (head); pos = pos->next)
 128
 129/*
 130 * Iterate forward over the elements list. The list elements can be
 131 * removed from the list while doing this.
 132 */
 133#define list_for_each_safe(pos, p, head) \
 134        for (pos = (head)->next, p = pos->next; \
 135                pos != (head); \
 136                pos = p, p = pos->next)
 137
 138/* Iterate backward over the elements of the list. */
 139#define list_for_each_prev(pos, head) \
 140        for (pos = (head)->prev; pos != (head); pos = pos->prev)
 141
 142/*
 143 * Iterate backwards over the elements list. The list elements can be
 144 * removed from the list while doing this.
 145 */
 146#define list_for_each_prev_safe(pos, p, head) \
 147        for (pos = (head)->prev, p = pos->prev; \
 148                pos != (head); \
 149                pos = p, p = pos->prev)
 150
 151static inline int list_empty(struct list_head *head)
 152{
 153        return head == head->next;
 154}
 155
 156static inline void list_replace_init(struct list_head *old,
 157                                     struct list_head *newp)
 158{
 159        struct list_head *head = old->next;
 160
 161        list_del(old);
 162        list_add_tail(newp, head);
 163        INIT_LIST_HEAD(old);
 164}
 165
 166#endif /* LIST_H */