db2/include/queue.h

   1 /*      BSDI $Id$       */
   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 #define LIST_FIRST(head)                ((head)->lh_first)
  85 #define LIST_NEXT(elm, field)           ((elm)->field.le_next)
  86 #define LIST_END(head)                  NULL
  87
  88 /*
  89  * List functions.
  90  */
  91 #define LIST_INIT(head) {                                               \
  92         (head)->lh_first = NULL;                                        \
  93 }
  94
  95 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
  96         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
  97                 (listelm)->field.le_next->field.le_prev =               \
  98                     &(elm)->field.le_next;                              \
  99         (listelm)->field.le_next = (elm);                               \
 100         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 101 } while (0)
 102
 103 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 104         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 105         (elm)->field.le_next = (listelm);                               \
 106         *(listelm)->field.le_prev = (elm);                              \
 107         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 108 } while (0)
 109
 110 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 111         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 112                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 113         (head)->lh_first = (elm);                                       \
 114         (elm)->field.le_prev = &(head)->lh_first;                       \
 115 } while (0)
 116
 117 #define LIST_REMOVE(elm, field) do {                                    \
 118         if ((elm)->field.le_next != NULL)                               \
 119                 (elm)->field.le_next->field.le_prev =                   \
 120                     (elm)->field.le_prev;                               \
 121         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 122 } while (0)
 123
 124 /*
 125  * Tail queue definitions.
 126  */
 127 #define TAILQ_HEAD(name, type)                                          \
 128 struct name {                                                           \
 129         struct type *tqh_first; /* first element */                     \
 130         struct type **tqh_last; /* addr of last next element */         \
 131 }
 132
 133 #define TAILQ_ENTRY(type)                                               \
 134 struct {                                                                \
 135         struct type *tqe_next;  /* next element */                      \
 136         struct type **tqe_prev; /* address of previous next element */  \
 137 }
 138
 139 #define TAILQ_FIRST(head)               ((head)->tqh_first)
 140 #define TAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
 141 #define TAILQ_END(head)                 NULL
 142
 143 /*
 144  * Tail queue functions.
 145  */
 146 #define TAILQ_INIT(head) do {                                           \
 147         (head)->tqh_first = NULL;                                       \
 148         (head)->tqh_last = &(head)->tqh_first;                          \
 149 } while (0)
 150
 151 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 152         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 153                 (head)->tqh_first->field.tqe_prev =                     \
 154                     &(elm)->field.tqe_next;                             \
 155         else                                                            \
 156                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 157         (head)->tqh_first = (elm);                                      \
 158         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 159 } while (0)
 160
 161 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 162         (elm)->field.tqe_next = NULL;                                   \
 163         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 164         *(head)->tqh_last = (elm);                                      \
 165         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 166 } while (0)
 167
 168 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 169         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 170                 (elm)->field.tqe_next->field.tqe_prev =                 \
 171                     &(elm)->field.tqe_next;                             \
 172         else                                                            \
 173                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 174         (listelm)->field.tqe_next = (elm);                              \
 175         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 176 } while (0)
 177
 178 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 179         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 180         (elm)->field.tqe_next = (listelm);                              \
 181         *(listelm)->field.tqe_prev = (elm);                             \
 182         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 183 } while (0)
 184
 185 #define TAILQ_REMOVE(head, elm, field) do {                             \
 186         if (((elm)->field.tqe_next) != NULL)                            \
 187                 (elm)->field.tqe_next->field.tqe_prev =                 \
 188                     (elm)->field.tqe_prev;                              \
 189         else                                                            \
 190                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 191         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 192 } while (0)
 193
 194 /*
 195  * Circular queue definitions.
 196  */
 197 #define CIRCLEQ_HEAD(name, type)                                        \
 198 struct name {                                                           \
 199         struct type *cqh_first;         /* first element */             \
 200         struct type *cqh_last;          /* last element */              \
 201 }
 202
 203 #define CIRCLEQ_ENTRY(type)                                             \
 204 struct {                                                                \
 205         struct type *cqe_next;          /* next element */              \
 206         struct type *cqe_prev;          /* previous element */          \
 207 }
 208
 209 #define CIRCLEQ_FIRST(head)             ((head)->cqh_first)
 210 #define CIRCLEQ_LAST(head)              ((head)->cqh_last)
 211 #define CIRCLEQ_END(head)               ((void *)(head))
 212 #define CIRCLEQ_NEXT(elm, field)        ((elm)->field.cqe_next)
 213 #define CIRCLEQ_PREV(elm, field)        ((elm)->field.cqe_prev)
 214
 215 /*
 216  * Circular queue functions.
 217  */
 218 #define CIRCLEQ_INIT(head) do {                                         \
 219         (head)->cqh_first = (void *)(head);                             \
 220         (head)->cqh_last = (void *)(head);                              \
 221 } while (0)
 222
 223 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 224         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 225         (elm)->field.cqe_prev = (listelm);                              \
 226         if ((listelm)->field.cqe_next == (void *)(head))                \
 227                 (head)->cqh_last = (elm);                               \
 228         else                                                            \
 229                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 230         (listelm)->field.cqe_next = (elm);                              \
 231 } while (0)
 232
 233 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
 234         (elm)->field.cqe_next = (listelm);                              \
 235         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 236         if ((listelm)->field.cqe_prev == (void *)(head))                \
 237                 (head)->cqh_first = (elm);                              \
 238         else                                                            \
 239                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 240         (listelm)->field.cqe_prev = (elm);                              \
 241 } while (0)
 242
 243 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
 244         (elm)->field.cqe_next = (head)->cqh_first;                      \
 245         (elm)->field.cqe_prev = (void *)(head);                         \
 246         if ((head)->cqh_last == (void *)(head))                         \
 247                 (head)->cqh_last = (elm);                               \
 248         else                                                            \
 249                 (head)->cqh_first->field.cqe_prev = (elm);              \
 250         (head)->cqh_first = (elm);                                      \
 251 } while (0)
 252
 253 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
 254         (elm)->field.cqe_next = (void *)(head);                         \
 255         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 256         if ((head)->cqh_first == (void *)(head))                        \
 257                 (head)->cqh_first = (elm);                              \
 258         else                                                            \
 259                 (head)->cqh_last->field.cqe_next = (elm);               \
 260         (head)->cqh_last = (elm);                                       \
 261 } while (0)
 262
 263 #define CIRCLEQ_REMOVE(head, elm, field) do {                           \
 264         if ((elm)->field.cqe_next == (void *)(head))                    \
 265                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 266         else                                                            \
 267                 (elm)->field.cqe_next->field.cqe_prev =                 \
 268                     (elm)->field.cqe_prev;                              \
 269         if ((elm)->field.cqe_prev == (void *)(head))                    \
 270                 (head)->cqh_first = (elm)->field.cqe_next;              \
 271         else                                                            \
 272                 (elm)->field.cqe_prev->field.cqe_next =                 \
 273                     (elm)->field.cqe_next;                              \
 274 } while (0)
 275 #endif  /* !_SYS_QUEUE_H_ */