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   1 /* Amanda $Id: queue.h,v 1.2 1999/05/24 16:10:35 kashmir Exp $ */
   2 /* from: $NetBSD: queue.h,v 1.16 1998/07/10 23:28:31 nathanw Exp $ */
   3
   4 /*
   5  * Copyright (c) 1991, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  *      @(#)queue.h     8.5 (Berkeley) 8/20/94
  37  */
  38
  39 #ifndef QUEUE_H
  40 #define QUEUE_H
  41
  42 /*
  43  * This file defines four types of data structures: lists, simple queues,
  44  * tail queues, and circular queues.
  45  *
  46  * A list is headed by a single forward pointer (or an array of forward
  47  * pointers for a hash table header). The elements are doubly linked
  48  * so that an arbitrary element can be removed without a need to
  49  * traverse the list. New elements can be added to the list before
  50  * or after an existing element or at the head of the list. A list
  51  * may only be traversed in the forward direction.
  52  *
  53  * A simple queue is headed by a pair of pointers, one the head of the
  54  * list and the other to the tail of the list. The elements are singly
  55  * linked to save space, so only elements can only be removed from the
  56  * head of the list. New elements can be added to the list before or after
  57  * an existing element, at the head of the list, or at the end of the
  58  * list. A simple queue may only be traversed in the forward direction.
  59  *
  60  * A tail queue is headed by a pair of pointers, one to the head of the
  61  * list and the other to the tail of the list. The elements are doubly
  62  * linked so that an arbitrary element can be removed without a need to
  63  * traverse the list. New elements can be added to the list before or
  64  * after an existing element, at the head of the list, or at the end of
  65  * the list. A tail queue may only be traversed in the forward direction.
  66  *
  67  * A circle queue is headed by a pair of pointers, one to the head of the
  68  * list and the other to the tail of the list. The elements are doubly
  69  * linked so that an arbitrary element can be removed without a need to
  70  * traverse the list. New elements can be added to the list before or after
  71  * an existing element, at the head of the list, or at the end of the list.
  72  * A circle queue may be traversed in either direction, but has a more
  73  * complex end of list detection.
  74  *
  75  * For details on the use of these macros, see the QUEUE-API document
  76  * in the docs directory.
  77  *
  78  * Note that the #undef's in this file exist so we override any
  79  * macros declared in <sys/queue.h>.
  80  */
  81
  82 /*
  83  * List definitions.
  84  */
  85 #undef LIST_HEAD
  86 #define LIST_HEAD(name, type)                                           \
  87 struct name {                                                           \
  88         struct type *lh_first;  /* first element */                     \
  89 }
  90
  91 #undef LIST_HEAD_INITIALIZER
  92 #define LIST_HEAD_INITIALIZER(head)                                     \
  93         { NULL }
  94
  95 #undef LIST_ENTRY
  96 #define LIST_ENTRY(type)                                                \
  97 struct {                                                                \
  98         struct type *le_next;   /* next element */                      \
  99         struct type **le_prev;  /* address of previous next element */  \
 100 }
 101
 102 /*
 103  * List functions.
 104  */
 105 #undef LIST_INIT
 106 #define LIST_INIT(head) do {                                            \
 107         (head)->lh_first = NULL;                                        \
 108 } while (0)
 109
 110 #undef LIST_INSERT_AFTER
 111 #define LIST_INSERT_AFTER(listelm, elm, field) do {                     \
 112         if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
 113                 (listelm)->field.le_next->field.le_prev =               \
 114                     &(elm)->field.le_next;                              \
 115         (listelm)->field.le_next = (elm);                               \
 116         (elm)->field.le_prev = &(listelm)->field.le_next;               \
 117 } while (0)
 118
 119 #undef LIST_INSERT_BEFORE
 120 #define LIST_INSERT_BEFORE(listelm, elm, field) do {                    \
 121         (elm)->field.le_prev = (listelm)->field.le_prev;                \
 122         (elm)->field.le_next = (listelm);                               \
 123         *(listelm)->field.le_prev = (elm);                              \
 124         (listelm)->field.le_prev = &(elm)->field.le_next;               \
 125 } while (0)
 126
 127 #undef LIST_INSERT_HEAD
 128 #define LIST_INSERT_HEAD(head, elm, field) do {                         \
 129         if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
 130                 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
 131         (head)->lh_first = (elm);                                       \
 132         (elm)->field.le_prev = &(head)->lh_first;                       \
 133 } while (0)
 134
 135 #undef LIST_REMOVE
 136 #define LIST_REMOVE(elm, field) do {                                    \
 137         if ((elm)->field.le_next != NULL)                               \
 138                 (elm)->field.le_next->field.le_prev =                   \
 139                     (elm)->field.le_prev;                               \
 140         *(elm)->field.le_prev = (elm)->field.le_next;                   \
 141 } while (0)
 142
 143 /*
 144  * List access methods.
 145  */
 146 #undef LIST_FIRST
 147 #define LIST_FIRST(head)                ((head)->lh_first)
 148
 149 #undef LIST_NEXT
 150 #define LIST_NEXT(elm, field)           ((elm)->field.le_next)
 151
 152 /*
 153  * Simple queue definitions.
 154  */
 155 #undef SIMPLEQ_HEAD
 156 #define SIMPLEQ_HEAD(name, type)                                        \
 157 struct name {                                                           \
 158         struct type *sqh_first; /* first element */                     \
 159         struct type **sqh_last; /* addr of last next element */         \
 160 }
 161
 162 #undef SIMPLEQ_HEAD_INITIALIZER
 163 #define SIMPLEQ_HEAD_INITIALIZER(head)                                  \
 164         { NULL, &(head).sqh_first }
 165
 166 #undef SIMPLEQ_ENTRY
 167 #define SIMPLEQ_ENTRY(type)                                             \
 168 struct {                                                                \
 169         struct type *sqe_next;  /* next element */                      \
 170 }
 171
 172 /*
 173  * Simple queue functions.
 174  */
 175 #undef SIMPLEQ_INIT
 176 #define SIMPLEQ_INIT(head) do {                                         \
 177         (head)->sqh_first = NULL;                                       \
 178         (head)->sqh_last = &(head)->sqh_first;                          \
 179 } while (0)
 180
 181 #undef SIMPLEQ_INSERT_HEAD
 182 #define SIMPLEQ_INSERT_HEAD(head, elm, field) do {                      \
 183         if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)        \
 184                 (head)->sqh_last = &(elm)->field.sqe_next;              \
 185         (head)->sqh_first = (elm);                                      \
 186 } while (0)
 187
 188 #undef SIMPLEQ_INSERT_TAIL
 189 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do {                      \
 190         (elm)->field.sqe_next = NULL;                                   \
 191         *(head)->sqh_last = (elm);                                      \
 192         (head)->sqh_last = &(elm)->field.sqe_next;                      \
 193 } while (0)
 194
 195 #undef SIMPLEQ_INSERT_AFTER
 196 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 197         if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
 198                 (head)->sqh_last = &(elm)->field.sqe_next;              \
 199         (listelm)->field.sqe_next = (elm);                              \
 200 } while (0)
 201
 202 #undef SIMPLEQ_REMOVE_HEAD
 203 #define SIMPLEQ_REMOVE_HEAD(head, elm, field) do {                      \
 204         if (((head)->sqh_first = (elm)->field.sqe_next) == NULL)        \
 205                 (head)->sqh_last = &(head)->sqh_first;                  \
 206 } while (0)
 207
 208 /*
 209  * Simple queue access methods.
 210  */
 211 #undef SIMPLEQ_FIRST
 212 #define SIMPLEQ_FIRST(head)             ((head)->sqh_first)
 213
 214 #undef SIMPLEQ_NEXT
 215 #define SIMPLEQ_NEXT(elm, field)        ((elm)->field.sqe_next)
 216
 217 /*
 218  * Tail queue definitions.
 219  */
 220 #undef TAILQ_HEAD
 221 #define TAILQ_HEAD(name, type)                                          \
 222 struct name {                                                           \
 223         struct type *tqh_first; /* first element */                     \
 224         struct type **tqh_last; /* addr of last next element */         \
 225 }
 226
 227 #undef TAILQ_HEAD_INITIALIZER
 228 #define TAILQ_HEAD_INITIALIZER(head)                                    \
 229         { NULL, &(head).tqh_first }
 230
 231 #undef TAILQ_ENTRY
 232 #define TAILQ_ENTRY(type)                                               \
 233 struct {                                                                \
 234         struct type *tqe_next;  /* next element */                      \
 235         struct type **tqe_prev; /* address of previous next element */  \
 236 }
 237
 238 /*
 239  * Tail queue functions.
 240  */
 241 #undef TAILQ_INIT
 242 #define TAILQ_INIT(head) do {                                           \
 243         (head)->tqh_first = NULL;                                       \
 244         (head)->tqh_last = &(head)->tqh_first;                          \
 245 } while (0)
 246
 247 #undef TAILQ_INSERT_HEAD
 248 #define TAILQ_INSERT_HEAD(head, elm, field) do {                        \
 249         if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
 250                 (head)->tqh_first->field.tqe_prev =                     \
 251                     &(elm)->field.tqe_next;                             \
 252         else                                                            \
 253                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 254         (head)->tqh_first = (elm);                                      \
 255         (elm)->field.tqe_prev = &(head)->tqh_first;                     \
 256 } while (0)
 257
 258 #undef TAILQ_INSERT_TAIL
 259 #define TAILQ_INSERT_TAIL(head, elm, field) do {                        \
 260         (elm)->field.tqe_next = NULL;                                   \
 261         (elm)->field.tqe_prev = (head)->tqh_last;                       \
 262         *(head)->tqh_last = (elm);                                      \
 263         (head)->tqh_last = &(elm)->field.tqe_next;                      \
 264 } while (0)
 265
 266 #undef TAILQ_INSERT_AFTER
 267 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {              \
 268         if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
 269                 (elm)->field.tqe_next->field.tqe_prev =                 \
 270                     &(elm)->field.tqe_next;                             \
 271         else                                                            \
 272                 (head)->tqh_last = &(elm)->field.tqe_next;              \
 273         (listelm)->field.tqe_next = (elm);                              \
 274         (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
 275 } while (0)
 276
 277 #undef TAILQ_INSERT_BEFORE
 278 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                   \
 279         (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
 280         (elm)->field.tqe_next = (listelm);                              \
 281         *(listelm)->field.tqe_prev = (elm);                             \
 282         (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
 283 } while (0)
 284
 285 #undef TAILQ_REMOVE
 286 #define TAILQ_REMOVE(head, elm, field) do {                             \
 287         if (((elm)->field.tqe_next) != NULL)                            \
 288                 (elm)->field.tqe_next->field.tqe_prev =                 \
 289                     (elm)->field.tqe_prev;                              \
 290         else                                                            \
 291                 (head)->tqh_last = (elm)->field.tqe_prev;               \
 292         *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
 293 } while (0)
 294
 295 /*
 296  * Tail queue access methods.
 297  */
 298 #undef TAILQ_FIRST
 299 #define TAILQ_FIRST(head)               ((head)->tqh_first)
 300
 301 #undef TAILQ_NEXT
 302 #define TAILQ_NEXT(elm, field)          ((elm)->field.tqe_next)
 303
 304 /*
 305  * Circular queue definitions.
 306  */
 307 #undef CIRCLEQ_HEAD
 308 #define CIRCLEQ_HEAD(name, type)                                        \
 309 struct name {                                                           \
 310         struct type *cqh_first;         /* first element */             \
 311         struct type *cqh_last;          /* last element */              \
 312 }
 313
 314 #undef CIRCLEQ_HEAD_INITIALIZER
 315 #define CIRCLEQ_HEAD_INITIALIZER(head)                                  \
 316         { (void *)&head, (void *)&head }
 317
 318 #undef CIRCLEQ_ENTRY
 319 #define CIRCLEQ_ENTRY(type)                                             \
 320 struct {                                                                \
 321         struct type *cqe_next;          /* next element */              \
 322         struct type *cqe_prev;          /* previous element */          \
 323 }
 324
 325 /*
 326  * Circular queue functions.
 327  */
 328 #undef CIRCLEQ_INIT
 329 #define CIRCLEQ_INIT(head) do {                                         \
 330         (head)->cqh_first = (void *)(head);                             \
 331         (head)->cqh_last = (void *)(head);                              \
 332 } while (0)
 333
 334 #undef CIRCLEQ_INSERT_AFTER
 335 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {            \
 336         (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
 337         (elm)->field.cqe_prev = (listelm);                              \
 338         if ((listelm)->field.cqe_next == (void *)(head))                \
 339                 (head)->cqh_last = (elm);                               \
 340         else                                                            \
 341                 (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
 342         (listelm)->field.cqe_next = (elm);                              \
 343 } while (0)
 344
 345 #undef CIRCLEQ_INSERT_BEFORE
 346 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {           \
 347         (elm)->field.cqe_next = (listelm);                              \
 348         (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
 349         if ((listelm)->field.cqe_prev == (void *)(head))                \
 350                 (head)->cqh_first = (elm);                              \
 351         else                                                            \
 352                 (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
 353         (listelm)->field.cqe_prev = (elm);                              \
 354 } while (0)
 355
 356 #undef CIRCLEQ_INSERT_HEAD
 357 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                      \
 358         (elm)->field.cqe_next = (head)->cqh_first;                      \
 359         (elm)->field.cqe_prev = (void *)(head);                         \
 360         if ((head)->cqh_last == (void *)(head))                         \
 361                 (head)->cqh_last = (elm);                               \
 362         else                                                            \
 363                 (head)->cqh_first->field.cqe_prev = (elm);              \
 364         (head)->cqh_first = (elm);                                      \
 365 } while (0)
 366
 367 #undef CIRCLEQ_INSERT_TAIL
 368 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                      \
 369         (elm)->field.cqe_next = (void *)(head);                         \
 370         (elm)->field.cqe_prev = (head)->cqh_last;                       \
 371         if ((head)->cqh_first == (void *)(head))                        \
 372                 (head)->cqh_first = (elm);                              \
 373         else                                                            \
 374                 (head)->cqh_last->field.cqe_next = (elm);               \
 375         (head)->cqh_last = (elm);                                       \
 376 } while (0)
 377
 378 #undef CIRCLEQ_REMOVE
 379 #define CIRCLEQ_REMOVE(head, elm, field) do {                           \
 380         if ((elm)->field.cqe_next == (void *)(head))                    \
 381                 (head)->cqh_last = (elm)->field.cqe_prev;               \
 382         else                                                            \
 383                 (elm)->field.cqe_next->field.cqe_prev =                 \
 384                     (elm)->field.cqe_prev;                              \
 385         if ((elm)->field.cqe_prev == (void *)(head))                    \
 386                 (head)->cqh_first = (elm)->field.cqe_next;              \
 387         else                                                            \
 388                 (elm)->field.cqe_prev->field.cqe_next =                 \
 389                     (elm)->field.cqe_next;                              \
 390 } while (0)
 391
 392 /*
 393  * Circular queue access methods.
 394  */
 395 #undef CIRCLEQ_FIRST
 396 #define CIRCLEQ_FIRST(head)             ((head)->cqh_first)
 397
 398 #undef CIRCLEQ_LAST
 399 #define CIRCLEQ_LAST(head)              ((head)->cqh_last)
 400
 401 #undef CIRCLEQ_NEXT
 402 #define CIRCLEQ_NEXT(elm, field)        ((elm)->field.cqe_next)
 403
 404 #undef CIRCLEQ_PREV
 405 #define CIRCLEQ_PREV(elm, field)        ((elm)->field.cqe_prev)
 406 #endif  /* !QUEUE_H */