include/list.h

   1 /* Copyright (C) 2002-2017 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _LIST_H
  20
  21 #ifndef __need_list_t
  22 # define _LIST_H        1
  23 #endif
  24
  25 /* The definitions of this file are adopted from those which can be
  26    found in the Linux kernel headers to enable people familiar with
  27    the latter find their way in these sources as well.  */
  28
  29
  30 #if defined __need_list_t || defined _LIST_H
  31 # ifndef __list_t_defined
  32 #  define __list_t_defined
  33 /* Basic type for the double-link list.  */
  34 typedef struct list_head
  35 {
  36   struct list_head *next;
  37   struct list_head *prev;
  38 } list_t;
  39 # endif
  40 # undef __need_list_t
  41 #endif
  42
  43 #ifdef _LIST_H
  44
  45 # include <atomic.h>
  46
  47 /* Define a variable with the head and tail of the list.  */
  48 # define LIST_HEAD(name) \
  49   list_t name = { &(name), &(name) }
  50
  51 /* Initialize a new list head.  */
  52 # define INIT_LIST_HEAD(ptr) \
  53   (ptr)->next = (ptr)->prev = (ptr)
  54
  55
  56 /* Add new element at the head of the list.  */
  57 static inline void
  58 list_add (list_t *newp, list_t *head)
  59 {
  60   newp->next = head->next;
  61   newp->prev = head;
  62   head->next->prev = newp;
  63   atomic_write_barrier ();
  64   head->next = newp;
  65 }
  66
  67
  68 /* Remove element from list.  */
  69 static inline void
  70 list_del (list_t *elem)
  71 {
  72   elem->next->prev = elem->prev;
  73   elem->prev->next = elem->next;
  74 }
  75
  76
  77 /* Join two lists.  */
  78 static inline void
  79 list_splice (list_t *add, list_t *head)
  80 {
  81   /* Do nothing if the list which gets added is empty.  */
  82   if (add != add->next)
  83     {
  84       add->next->prev = head;
  85       add->prev->next = head->next;
  86       head->next->prev = add->prev;
  87       head->next = add->next;
  88     }
  89 }
  90
  91
  92 /* Get typed element from list at a given position.  */
  93 # define list_entry(ptr, type, member) \
  94   ((type *) ((char *) (ptr) - (unsigned long) (&((type *) 0)->member)))
  95
  96
  97
  98 /* Iterate forward over the elements of the list.  */
  99 # define list_for_each(pos, head) \
 100   for (pos = (head)->next; pos != (head); pos = pos->next)
 101
 102
 103 /* Iterate forward over the elements of the list.  */
 104 # define list_for_each_prev(pos, head) \
 105   for (pos = (head)->prev; pos != (head); pos = pos->prev)
 106
 107
 108 /* Iterate backwards over the elements list.  The list elements can be
 109    removed from the list while doing this.  */
 110 # define list_for_each_prev_safe(pos, p, head) \
 111   for (pos = (head)->prev, p = pos->prev; \
 112        pos != (head); \
 113        pos = p, p = pos->prev)
 114
 115 #endif /* _LIST_H */
 116
 117 #endif  /* list.h */