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 /* Join two lists.  */
  92 static inline void
  93 list_splice (list_t *add, list_t *head)
  94 {
  95   /* Do nothing if the list which gets added is empty.  */
  96   if (add != add->next)
  97     {
  98       add->next->prev = head;
  99       add->prev->next = head->next;
 100       head->next->prev = add->prev;
 101       head->next = add->next;
 102     }
 103 }
 104
 105
 106 /* Get typed element from list at a given position.  */
 107 #define list_entry(ptr, type, member) \
 108   ((type *) ((char *) (ptr) - (unsigned long) (&((type *) 0)->member)))
 109
 110
 111
 112 /* Iterate forward over the elements of the list.  */
 113 #define list_for_each(pos, head) \
 114   for (pos = (head)->next; pos != (head); pos = pos->next)
 115
 116
 117 /* Iterate forward over the elements of the list.  */
 118 #define list_for_each_prev(pos, head) \
 119   for (pos = (head)->prev; pos != (head); pos = pos->prev)
 120
 121
 122 /* Iterate backwards over the elements list.  The list elements can be
 123    removed from the list while doing this.  */
 124 #define list_for_each_prev_safe(pos, p, head) \
 125   for (pos = (head)->prev, p = pos->prev; \
 126        pos != (head); \
 127        pos = p, p = pos->prev)
 128
 129 #define list_for_each_entry(pos, head, member)                          \
 130         for (pos = list_entry((head)->next, typeof(*pos), member);      \
 131              &pos->member != (head);                                    \
 132              pos = list_entry(pos->member.next, typeof(*pos), member))
 133
 134 #define list_for_each_entry_reverse(pos, head, member)                  \
 135         for (pos = list_entry((head)->prev, typeof(*pos), member);      \
 136              &pos->member != (head);                                    \
 137              pos = list_entry(pos->member.prev, typeof(*pos), member))
 138
 139 #define list_for_each_entry_safe(pos, p, head, member)                  \
 140         for (pos = list_entry((head)->next, typeof(*pos), member),      \
 141                      p = list_entry(pos->member.next,typeof(*pos), member); \
 142              &pos->member != (head);                                    \
 143              pos = p, p = list_entry(pos->member.next, typeof(*pos), member))
 144
 145 static inline int list_empty(list_t *head)
 146 {
 147         return head == head->next;
 148 }
 149
 150 static inline void list_replace_init(list_t *old,
 151                                      list_t *new)
 152 {
 153         list_t *head = old->next;
 154         list_del(old);
 155         list_add_tail(new, head);
 156         INIT_LIST_HEAD(old);
 157 }
 158
 159 #endif  /* list.h */