include/sys/queue.h

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