dist/nvi/include/sys/queue.h

   1 /*      $NetBSD$ */
   2
   3 /*
   4  * Copyright (c) 1991, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. All advertising materials mentioning features or use of this software
  16  *    must display the following acknowledgement:
  17  *      This product includes software developed by the University of
  18  *      California, Berkeley and its contributors.
  19  * 4. Neither the name of the University nor the names of its contributors
  20  *    may be used to endorse or promote products derived from this software
  21  *    without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  36  */
  37
  38 #ifndef _SYS_QUEUE_H_
  39 #define _SYS_QUEUE_H_
  40
  41 /*
  42  * This file defines three types of data structures: lists, tail queues,
  43  * and circular queues.
  44  *
  45  * A list is headed by a single forward pointer (or an array of forward
  46  * pointers for a hash table header). The elements are doubly linked
  47  * so that an arbitrary element can be removed without a need to
  48  * traverse the list. New elements can be added to the list before
  49  * or after an existing element or at the head of the list. A list
  50  * may only be traversed in the forward direction.
  51  *
  52  * A tail queue is headed by a pair of pointers, one to the head of the
  53  * list and the other to the tail of the list. The elements are doubly
  54  * linked so that an arbitrary element can be removed without a need to
  55  * traverse the list. New elements can be added to the list before or
  56  * after an existing element, at the head of the list, or at the end of
  57  * the list. A tail queue may only be traversed in the forward direction.
  58  *
  59  * A circle queue is headed by a pair of pointers, one to the head of the
  60  * list and the other to the tail of the list. The elements are doubly
  61  * linked so that an arbitrary element can be removed without a need to
  62  * traverse the list. New elements can be added to the list before or after
  63  * an existing element, at the head of the list, or at the end of the list.
  64  * A circle queue may be traversed in either direction, but has a more
  65  * complex end of list detection.
  66  *
  67  * For details on the use of these macros, see the queue(3) manual page.
  68  */
  69
  70 /*
  71  * List definitions.
  72  */
  73 #define LIST_HEAD(name, type)                                           \
  74 struct name {                                                           \
  75         struct type *lh_first;  /* first element */                     \
  76 }
  77
  78 #define LIST_ENTRY(type)                                                \
  79 struct {                                                                \
  80         struct type *le_next;   /* next element */                      \
  81         struct type **le_prev;  /* address of previous next element */  \
  82 }
  83
  84 /*
  85  * List functions.
  86  */
  87 #define LIST_INIT(head) {                                               \
  88         (head)->lh_first = NULL;                                        \
  89 }
  90
  91 #define LIST_INSERT_AFTER(listelm, elm, field) {                        \
  92         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
  93                 (listelm)->field.le_next->field.le_prev =               \
  94                     &(elm)->field.le_next;                              \
  95         (listelm)->field.le_next = (elm);                               \
  96         (elm)->field.le_prev = &(listelm)->field.le_next;               \
  97 }
  98
  99 #define LIST_INSERT_BEFORE(listelm, elm, field) {                       \
 100         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 101         (elm)->field.le_next = (listelm);                               \
 102         *(listelm)->field.le_prev = (elm);                              \
 103         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 104 }
 105
 106 #define LIST_INSERT_HEAD(head, elm, field) {                            \
 107         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 108                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 109         (head)->lh_first = (elm);                                       \
 110         (elm)->field.le_prev = &(head)->lh_first;                       \
 111 }
 112
 113 #define LIST_REMOVE(elm, field) {                                       \
 114         if ((elm)->field.le_next != NULL)                               \
 115                 (elm)->field.le_next->field.le_prev =                   \
 116                     (elm)->field.le_prev;                               \
 117         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 118 }
 119
 120 /*
 121  * Tail queue definitions.
 122  */
 123 #define TAILQ_HEAD(name, type)                                          \
 124 struct name {                                                           \
 125         struct type *tqh_first; /* first element */                     \
 126         struct type **tqh_last; /* addr of last next element */         \
 127 }
 128
 129 #define TAILQ_ENTRY(type)                                               \
 130 struct {                                                                \
 131         struct type *tqe_next;  /* next element */                      \
 132         struct type **tqe_prev; /* address of previous next element */  \
 133 }
 134
 135 /*
 136  * Tail queue functions.
 137  */
 138 #define TAILQ_INIT(head) {                                              \
 139         (head)->tqh_first = NULL;                                       \
 140         (head)->tqh_last = &(head)->tqh_first;                          \
 141 }
 142
 143 #define TAILQ_INSERT_HEAD(head, elm, field) {                           \
 144         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 145                 (head)->tqh_first->field.tqe_prev =                     \
 146                     &(elm)->field.tqe_next;                             \
 147         else                                                            \
 148                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 149         (head)->tqh_first = (elm);                                      \
 150         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 151 }
 152
 153 #define TAILQ_INSERT_TAIL(head, elm, field) {                           \
 154         (elm)->field.tqe_next = NULL;                                   \
 155         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 156         *(head)->tqh_last = (elm);                                      \
 157         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 158 }
 159
 160 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) {                 \
 161         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 162                 (elm)->field.tqe_next->field.tqe_prev =                 \
 163                     &(elm)->field.tqe_next;                             \
 164         else                                                            \
 165                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 166         (listelm)->field.tqe_next = (elm);                              \
 167         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 168 }
 169
 170 #define TAILQ_INSERT_BEFORE(listelm, elm, field) {                      \
 171         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 172         (elm)->field.tqe_next = (listelm);                              \
 173         *(listelm)->field.tqe_prev = (elm);                             \
 174         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 175 }
 176
 177 #define TAILQ_REMOVE(head, elm, field) {                                \
 178         if (((elm)->field.tqe_next) != NULL)                            \
 179                 (elm)->field.tqe_next->field.tqe_prev =                 \
 180                     (elm)->field.tqe_prev;                              \
 181         else                                                            \
 182                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 183         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 184 }
 185
 186 /*
 187  * Circular queue definitions.
 188  */
 189 #define CIRCLEQ_HEAD(name, type)                                        \
 190 struct name {                                                           \
 191         struct type *cqh_first;         /* first element */             \
 192         struct type *cqh_last;          /* last element */              \
 193 }
 194
 195 #define CIRCLEQ_ENTRY(type)                                             \
 196 struct {                                                                \
 197         struct type *cqe_next;          /* next element */              \
 198         struct type *cqe_prev;          /* previous element */          \
 199 }
 200
 201 /*
 202  * Circular queue functions.
 203  */
 204 #define CIRCLEQ_INIT(head) {                                            \
 205         (head)->cqh_first = (void *)(head);                             \
 206         (head)->cqh_last = (void *)(head);                              \
 207 }
 208
 209 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) {               \
 210         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 211         (elm)->field.cqe_prev = (listelm);                              \
 212         if ((listelm)->field.cqe_next == (void *)(head))                \
 213                 (head)->cqh_last = (elm);                               \
 214         else                                                            \
 215                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 216         (listelm)->field.cqe_next = (elm);                              \
 217 }
 218
 219 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) {              \
 220         (elm)->field.cqe_next = (listelm);                              \
 221         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 222         if ((listelm)->field.cqe_prev == (void *)(head))                \
 223                 (head)->cqh_first = (elm);                              \
 224         else                                                            \
 225                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 226         (listelm)->field.cqe_prev = (elm);                              \
 227 }
 228
 229 #define CIRCLEQ_INSERT_HEAD(head, elm, field) {                         \
 230         (elm)->field.cqe_next = (head)->cqh_first;                      \
 231         (elm)->field.cqe_prev = (void *)(head);                         \
 232         if ((head)->cqh_last == (void *)(head))                         \
 233                 (head)->cqh_last = (elm);                               \
 234         else                                                            \
 235                 (head)->cqh_first->field.cqe_prev = (elm);              \
 236         (head)->cqh_first = (elm);                                      \
 237 }
 238
 239 #define CIRCLEQ_INSERT_TAIL(head, elm, field) {                         \
 240         (elm)->field.cqe_next = (void *)(head);                         \
 241         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 242         if ((head)->cqh_first == (void *)(head))                        \
 243                 (head)->cqh_first = (elm);                              \
 244         else                                                            \
 245                 (head)->cqh_last->field.cqe_next = (elm);               \
 246         (head)->cqh_last = (elm);                                       \
 247 }
 248
 249 #define CIRCLEQ_REMOVE(head, elm, field) {                              \
 250         if ((elm)->field.cqe_next == (void *)(head))                    \
 251                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 252         else                                                            \
 253                 (elm)->field.cqe_next->field.cqe_prev =                 \
 254                     (elm)->field.cqe_prev;                              \
 255         if ((elm)->field.cqe_prev == (void *)(head))                    \
 256                 (head)->cqh_first = (elm)->field.cqe_next;              \
 257         else                                                            \
 258                 (elm)->field.cqe_prev->field.cqe_next =                 \
 259                     (elm)->field.cqe_next;                              \
 260 }
 261 #endif  /* !_SYS_QUEUE_H_ */