urcu/list.h

   1 /* Copyright (C) 2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #ifndef _LIST_H
  21 #define _LIST_H 1
  22
  23 /* The definitions of this file are adopted from those which can be
  24    found in the Linux kernel headers to enable people familiar with
  25    the latter find their way in these sources as well.  */
  26
  27
  28 /* Basic type for the double-link list.  */
  29 typedef struct list_head
  30 {
  31   struct list_head *next;
  32   struct list_head *prev;
  33 } list_t;
  34
  35
  36 /* Define a variable with the head and tail of the list.  */
  37 #define LIST_HEAD(name) \
  38   list_t name = { &(name), &(name) }
  39
  40 /* Initialize a new list head.  */
  41 #define INIT_LIST_HEAD(ptr) \
  42   (ptr)->next = (ptr)->prev = (ptr)
  43
  44 #define LIST_HEAD_INIT(name) { .prev = &(name), .next = &(name) }
  45
  46 /* Add new element at the head of the list.  */
  47 static inline void
  48 list_add (list_t *newp, list_t *head)
  49 {
  50   head->next->prev = newp;
  51   newp->next = head->next;
  52   newp->prev = head;
  53   head->next = newp;
  54 }
  55
  56
  57 /* Add new element at the tail of the list.  */
  58 static inline void
  59 list_add_tail (list_t *newp, list_t *head)
  60 {
  61   head->prev->next = newp;
  62   newp->next = head;
  63   newp->prev = head->prev;
  64   head->prev = newp;
  65 }
  66
  67
  68 /* Remove element from list.  */
  69 static inline void
  70 __list_del (list_t *prev, list_t *next)
  71 {
  72   next->prev = prev;
  73   prev->next = next;
  74 }
  75
  76 /* Remove element from list.  */
  77 static inline void
  78 list_del (list_t *elem)
  79 {
  80   __list_del (elem->prev, elem->next);
  81 }
  82
  83 /* delete from list, add to another list as head */
  84 static inline void
  85 list_move (list_t *elem, list_t *head)
  86 {
  87   __list_del (elem->prev, elem->next);
  88   list_add (elem, head);
  89 }
  90
  91 /* replace an old entry.
  92  */
  93 static inline void
  94 list_replace(list_t *old, list_t *_new)
  95 {
  96         _new->next = old->next;
  97         _new->prev = old->prev;
  98         _new->prev->next = _new;
  99         _new->next->prev = _new;
 100 }
 101
 102 /* Join two lists.  */
 103 static inline void
 104 list_splice (list_t *add, list_t *head)
 105 {
 106   /* Do nothing if the list which gets added is empty.  */
 107   if (add != add->next)
 108     {
 109       add->next->prev = head;
 110       add->prev->next = head->next;
 111       head->next->prev = add->prev;
 112       head->next = add->next;
 113     }
 114 }
 115
 116
 117 /* Get typed element from list at a given position.  */
 118 #define list_entry(ptr, type, member) \
 119   ((type *) ((char *) (ptr) - (unsigned long) (&((type *) 0)->member)))
 120
 121
 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 of the list.  */
 129 #define list_for_each_prev(pos, head) \
 130   for (pos = (head)->prev; pos != (head); pos = pos->prev)
 131
 132
 133 /* Iterate backwards over the elements list.  The list elements can be
 134    removed from the list while doing this.  */
 135 #define list_for_each_prev_safe(pos, p, head) \
 136   for (pos = (head)->prev, p = pos->prev; \
 137        pos != (head); \
 138        pos = p, p = pos->prev)
 139
 140 #define list_for_each_entry(pos, head, member)                          \
 141         for (pos = list_entry((head)->next, typeof(*pos), member);      \
 142              &pos->member != (head);                                    \
 143              pos = list_entry(pos->member.next, typeof(*pos), member))
 144
 145 #define list_for_each_entry_reverse(pos, head, member)                  \
 146         for (pos = list_entry((head)->prev, typeof(*pos), member);      \
 147              &pos->member != (head);                                    \
 148              pos = list_entry(pos->member.prev, typeof(*pos), member))
 149
 150 #define list_for_each_entry_safe(pos, p, head, member)                  \
 151         for (pos = list_entry((head)->next, typeof(*pos), member),      \
 152                      p = list_entry(pos->member.next,typeof(*pos), member); \
 153              &pos->member != (head);                                    \
 154              pos = p, p = list_entry(pos->member.next, typeof(*pos), member))
 155
 156 static inline int list_empty(list_t *head)
 157 {
 158         return head == head->next;
 159 }
 160
 161 static inline void list_replace_init(list_t *old,
 162                                      list_t *_new)
 163 {
 164         list_t *head = old->next;
 165         list_del(old);
 166         list_add_tail(_new, head);
 167         INIT_LIST_HEAD(old);
 168 }
 169
 170 #endif  /* list.h */