Andrew's git / gitweb.git /
f65edce14888a84ef0860edf8ec7523470ed2468
   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/* Define a variable with the head and tail of the list. */
  40#define LIST_HEAD(name) \
  41        struct list_head name = { &(name), &(name) }
  42
  43/* Initialize a new list head. */
  44#define INIT_LIST_HEAD(ptr) \
  45        (ptr)->next = (ptr)->prev = (ptr)
  46
  47#define LIST_HEAD_INIT(name) { &(name), &(name) }
  48
  49/* Add new element at the head of the list. */
  50static inline void list_add(struct list_head *newp, struct list_head *head)
  51{
  52        head->next->prev = newp;
  53        newp->next = head->next;
  54        newp->prev = head;
  55        head->next = newp;
  56}
  57
  58/* Add new element at the tail of the list. */
  59static inline void list_add_tail(struct list_head *newp, struct list_head *head)
  60{
  61        head->prev->next = newp;
  62        newp->next = head;
  63        newp->prev = head->prev;
  64        head->prev = newp;
  65}
  66
  67/* Remove element from list. */
  68static inline void __list_del(struct list_head *prev, struct list_head *next)
  69{
  70        next->prev = prev;
  71        prev->next = next;
  72}
  73
  74/* Remove element from list. */
  75static inline void list_del(struct list_head *elem)
  76{
  77        __list_del(elem->prev, elem->next);
  78}
  79
  80/* Remove element from list, initializing the element's list pointers. */
  81static inline void list_del_init(struct list_head *elem)
  82{
  83        list_del(elem);
  84        INIT_LIST_HEAD(elem);
  85}
  86
  87/* Delete from list, add to another list as head. */
  88static inline void list_move(struct list_head *elem, struct list_head *head)
  89{
  90        __list_del(elem->prev, elem->next);
  91        list_add(elem, head);
  92}
  93
  94/* Replace an old entry. */
  95static inline void list_replace(struct list_head *old, struct list_head *newp)
  96{
  97        newp->next = old->next;
  98        newp->prev = old->prev;
  99        newp->prev->next = newp;
 100        newp->next->prev = newp;
 101}
 102
 103/* Join two lists. */
 104static inline void list_splice(struct list_head *add, struct list_head *head)
 105{
 106        /* Do nothing if the list which gets added is empty. */
 107        if (add != add->next) {
 108                add->next->prev = head;
 109                add->prev->next = head->next;
 110                head->next->prev = add->prev;
 111                head->next = add->next;
 112        }
 113}
 114
 115/* Get typed element from list at a given position. */
 116#define list_entry(ptr, type, member) \
 117        ((type *) ((char *) (ptr) - offsetof(type, member)))
 118
 119/* Get first entry from a list. */
 120#define list_first_entry(ptr, type, member) \
 121        list_entry((ptr)->next, type, member)
 122
 123/* Iterate forward over the elements of the list. */
 124#define list_for_each(pos, head) \
 125        for (pos = (head)->next; pos != (head); pos = pos->next)
 126
 127/*
 128 * Iterate forward over the elements list. The list elements can be
 129 * removed from the list while doing this.
 130 */
 131#define list_for_each_safe(pos, p, head) \
 132        for (pos = (head)->next, p = pos->next; \
 133                pos != (head); \
 134                pos = p, p = pos->next)
 135
 136/* Iterate backward over the elements of the list. */
 137#define list_for_each_prev(pos, head) \
 138        for (pos = (head)->prev; pos != (head); pos = pos->prev)
 139
 140/*
 141 * Iterate backwards over the elements list. The list elements can be
 142 * removed from the list while doing this.
 143 */
 144#define list_for_each_prev_safe(pos, p, head) \
 145        for (pos = (head)->prev, p = pos->prev; \
 146                pos != (head); \
 147                pos = p, p = pos->prev)
 148
 149static inline int list_empty(struct list_head *head)
 150{
 151        return head == head->next;
 152}
 153
 154static inline void list_replace_init(struct list_head *old,
 155                                     struct list_head *newp)
 156{
 157        struct list_head *head = old->next;
 158
 159        list_del(old);
 160        list_add_tail(newp, head);
 161        INIT_LIST_HEAD(old);
 162}
 163
 164#endif /* LIST_H */