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  1. /*    $NetBSD: queue.h,v 1.39 2004/04/18 14:25:34 lukem Exp $    */
  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. Neither the name of the University nor the names of its contributors
  16.  *    may be used to endorse or promote products derived from this software
  17.  *    without specific prior written permission.
  18.  *
  19.  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  20.  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  21.  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  22.  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  23.  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  24.  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  25.  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  26.  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  27.  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  28.  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  29.  * SUCH DAMAGE.
  30.  *
  31.  *    @(#)queue.h    8.5 (Berkeley) 8/20/94
  32.  */
  33.  
  34. #ifndef    _SYS_QUEUE_H_
  35. #define    _SYS_QUEUE_H_
  36.  
  37. /*
  38.  * This file defines five types of data structures: singly-linked lists,
  39.  * lists, simple queues, tail queues, and circular queues.
  40.  *
  41.  * A singly-linked list is headed by a single forward pointer. The
  42.  * elements are singly linked for minimum space and pointer manipulation
  43.  * overhead at the expense of O(n) removal for arbitrary elements. New
  44.  * elements can be added to the list after an existing element or at the
  45.  * head of the list.  Elements being removed from the head of the list
  46.  * should use the explicit macro for this purpose for optimum
  47.  * efficiency. A singly-linked list may only be traversed in the forward
  48.  * direction.  Singly-linked lists are ideal for applications with large
  49.  * datasets and few or no removals or for implementing a LIFO queue.
  50.  *
  51.  * A list is headed by a single forward pointer (or an array of forward
  52.  * pointers for a hash table header). The elements are doubly linked
  53.  * so that an arbitrary element can be removed without a need to
  54.  * traverse the list. New elements can be added to the list before
  55.  * or after an existing element or at the head of the list. A list
  56.  * may only be traversed in the forward direction.
  57.  *
  58.  * A simple queue is headed by a pair of pointers, one the head of the
  59.  * list and the other to the tail of the list. The elements are singly
  60.  * linked to save space, so only elements can only be removed from the
  61.  * head of the list. New elements can be added to the list after
  62.  * an existing element, at the head of the list, or at the end of the
  63.  * list. A simple queue may only be traversed in the forward direction.
  64.  *
  65.  * A tail queue is headed by a pair of pointers, one to the head of the
  66.  * list and the other to the tail of the list. The elements are doubly
  67.  * linked so that an arbitrary element can be removed without a need to
  68.  * traverse the list. New elements can be added to the list before or
  69.  * after an existing element, at the head of the list, or at the end of
  70.  * the list. A tail queue may be traversed in either direction.
  71.  *
  72.  * A circle queue is headed by a pair of pointers, one to the head of the
  73.  * list and the other to the tail of the list. The elements are doubly
  74.  * linked so that an arbitrary element can be removed without a need to
  75.  * traverse the list. New elements can be added to the list before or after
  76.  * an existing element, at the head of the list, or at the end of the list.
  77.  * A circle queue may be traversed in either direction, but has a more
  78.  * complex end of list detection.
  79.  *
  80.  * For details on the use of these macros, see the queue(3) manual page.
  81.  */
  82.  
  83. /*
  84.  * List definitions.
  85.  */
  86. #define    LIST_HEAD(name, type)                        \
  87. struct name {                                \
  88.     struct type *lh_first;    /* first element */            \
  89. }
  90.  
  91. #define    LIST_HEAD_INITIALIZER(head)                    \
  92.     { NULL }
  93.  
  94. #define    LIST_ENTRY(type)                        \
  95. struct {                                \
  96.     struct type *le_next;    /* next element */            \
  97.     struct type **le_prev;    /* address of previous next element */    \
  98. }
  99.  
  100. /*
  101.  * List functions.
  102.  */
  103. #if defined(_KERNEL) && defined(QUEUEDEBUG)
  104. #define    QUEUEDEBUG_LIST_INSERT_HEAD(head, elm, field)            \
  105.     if ((head)->lh_first &&                        \
  106.         (head)->lh_first->field.le_prev != &(head)->lh_first)    \
  107.         panic("LIST_INSERT_HEAD %p %s:%d", (head), __FILE__, __LINE__);
  108. #define    QUEUEDEBUG_LIST_OP(elm, field)                    \
  109.     if ((elm)->field.le_next &&                    \
  110.         (elm)->field.le_next->field.le_prev !=            \
  111.         &(elm)->field.le_next)                    \
  112.         panic("LIST_* forw %p %s:%d", (elm), __FILE__, __LINE__);\
  113.     if (*(elm)->field.le_prev != (elm))                \
  114.         panic("LIST_* back %p %s:%d", (elm), __FILE__, __LINE__);
  115. #define    QUEUEDEBUG_LIST_POSTREMOVE(elm, field)                \
  116.     (elm)->field.le_next = (void *)1L;                \
  117.     (elm)->field.le_prev = (void *)1L;
  118. #else
  119. #define    QUEUEDEBUG_LIST_INSERT_HEAD(head, elm, field)
  120. #define    QUEUEDEBUG_LIST_OP(elm, field)
  121. #define    QUEUEDEBUG_LIST_POSTREMOVE(elm, field)
  122. #endif
  123.  
  124. #define    LIST_INIT(head) do {                        \
  125.     (head)->lh_first = NULL;                    \
  126. } while (/*CONSTCOND*/0)
  127.  
  128. #define    LIST_INSERT_AFTER(listelm, elm, field) do {            \
  129.     QUEUEDEBUG_LIST_OP((listelm), field)                \
  130.     if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)    \
  131.         (listelm)->field.le_next->field.le_prev =        \
  132.             &(elm)->field.le_next;                \
  133.     (listelm)->field.le_next = (elm);                \
  134.     (elm)->field.le_prev = &(listelm)->field.le_next;        \
  135. } while (/*CONSTCOND*/0)
  136.  
  137. #define    LIST_INSERT_BEFORE(listelm, elm, field) do {            \
  138.     QUEUEDEBUG_LIST_OP((listelm), field)                \
  139.     (elm)->field.le_prev = (listelm)->field.le_prev;        \
  140.     (elm)->field.le_next = (listelm);                \
  141.     *(listelm)->field.le_prev = (elm);                \
  142.     (listelm)->field.le_prev = &(elm)->field.le_next;        \
  143. } while (/*CONSTCOND*/0)
  144.  
  145. #define    LIST_INSERT_HEAD(head, elm, field) do {                \
  146.     QUEUEDEBUG_LIST_INSERT_HEAD((head), (elm), field)        \
  147.     if (((elm)->field.le_next = (head)->lh_first) != NULL)        \
  148.         (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
  149.     (head)->lh_first = (elm);                    \
  150.     (elm)->field.le_prev = &(head)->lh_first;            \
  151. } while (/*CONSTCOND*/0)
  152.  
  153. #define    LIST_REMOVE(elm, field) do {                    \
  154.     QUEUEDEBUG_LIST_OP((elm), field)                \
  155.     if ((elm)->field.le_next != NULL)                \
  156.         (elm)->field.le_next->field.le_prev =             \
  157.             (elm)->field.le_prev;                \
  158.     *(elm)->field.le_prev = (elm)->field.le_next;            \
  159.     QUEUEDEBUG_LIST_POSTREMOVE((elm), field)            \
  160. } while (/*CONSTCOND*/0)
  161.  
  162. #define    LIST_FOREACH(var, head, field)                    \
  163.     for ((var) = ((head)->lh_first);                \
  164.         (var);                            \
  165.         (var) = ((var)->field.le_next))
  166.  
  167. /*
  168.  * List access methods.
  169.  */
  170. #define    LIST_EMPTY(head)        ((head)->lh_first == NULL)
  171. #define    LIST_FIRST(head)        ((head)->lh_first)
  172. #define    LIST_NEXT(elm, field)        ((elm)->field.le_next)
  173.  
  174.  
  175. /*
  176.  * Singly-linked List definitions.
  177.  */
  178. #define    SLIST_HEAD(name, type)                        \
  179. struct name {                                \
  180.     struct type *slh_first;    /* first element */            \
  181. }
  182.  
  183. #define    SLIST_HEAD_INITIALIZER(head)                    \
  184.     { NULL }
  185.  
  186. #define    SLIST_ENTRY(type)                        \
  187. struct {                                \
  188.     struct type *sle_next;    /* next element */            \
  189. }
  190.  
  191. /*
  192.  * Singly-linked List functions.
  193.  */
  194. #define    SLIST_INIT(head) do {                        \
  195.     (head)->slh_first = NULL;                    \
  196. } while (/*CONSTCOND*/0)
  197.  
  198. #define    SLIST_INSERT_AFTER(slistelm, elm, field) do {            \
  199.     (elm)->field.sle_next = (slistelm)->field.sle_next;        \
  200.     (slistelm)->field.sle_next = (elm);                \
  201. } while (/*CONSTCOND*/0)
  202.  
  203. #define    SLIST_INSERT_HEAD(head, elm, field) do {            \
  204.     (elm)->field.sle_next = (head)->slh_first;            \
  205.     (head)->slh_first = (elm);                    \
  206. } while (/*CONSTCOND*/0)
  207.  
  208. #define    SLIST_REMOVE_HEAD(head, field) do {                \
  209.     (head)->slh_first = (head)->slh_first->field.sle_next;        \
  210. } while (/*CONSTCOND*/0)
  211.  
  212. #define    SLIST_REMOVE(head, elm, type, field) do {            \
  213.     if ((head)->slh_first == (elm)) {                \
  214.         SLIST_REMOVE_HEAD((head), field);            \
  215.     }                                \
  216.     else {                                \
  217.         struct type *curelm = (head)->slh_first;        \
  218.         while(curelm->field.sle_next != (elm))            \
  219.             curelm = curelm->field.sle_next;        \
  220.         curelm->field.sle_next =                \
  221.             curelm->field.sle_next->field.sle_next;        \
  222.     }                                \
  223. } while (/*CONSTCOND*/0)
  224.  
  225. #define    SLIST_FOREACH(var, head, field)                    \
  226.     for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
  227.  
  228. /*
  229.  * Singly-linked List access methods.
  230.  */
  231. #define    SLIST_EMPTY(head)    ((head)->slh_first == NULL)
  232. #define    SLIST_FIRST(head)    ((head)->slh_first)
  233. #define    SLIST_NEXT(elm, field)    ((elm)->field.sle_next)
  234.  
  235.  
  236. /*
  237.  * Singly-linked Tail queue declarations.
  238.  */
  239. #define    STAILQ_HEAD(name, type)                    \
  240. struct name {                                \
  241.     struct type *stqh_first;    /* first element */            \
  242.     struct type **stqh_last;    /* addr of last next element */        \
  243. }
  244.  
  245. #define    STAILQ_HEAD_INITIALIZER(head)                    \
  246.     { NULL, &(head).stqh_first }
  247.  
  248. #define    STAILQ_ENTRY(type)                        \
  249. struct {                                \
  250.     struct type *stqe_next;    /* next element */            \
  251. }
  252.  
  253. /*
  254.  * Singly-linked Tail queue functions.
  255.  */
  256. #define    STAILQ_INIT(head) do {                        \
  257.     (head)->stqh_first = NULL;                    \
  258.     (head)->stqh_last = &(head)->stqh_first;                \
  259. } while (/*CONSTCOND*/0)
  260.  
  261. #define    STAILQ_INSERT_HEAD(head, elm, field) do {            \
  262.     if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)    \
  263.         (head)->stqh_last = &(elm)->field.stqe_next;        \
  264.     (head)->stqh_first = (elm);                    \
  265. } while (/*CONSTCOND*/0)
  266.  
  267. #define    STAILQ_INSERT_TAIL(head, elm, field) do {            \
  268.     (elm)->field.stqe_next = NULL;                    \
  269.     *(head)->stqh_last = (elm);                    \
  270.     (head)->stqh_last = &(elm)->field.stqe_next;            \
  271. } while (/*CONSTCOND*/0)
  272.  
  273. #define    STAILQ_INSERT_AFTER(head, listelm, elm, field) do {        \
  274.     if (((elm)->field.stqe_next = (listelm)->field.stqe_next) == NULL)\
  275.         (head)->stqh_last = &(elm)->field.stqe_next;        \
  276.     (listelm)->field.stqe_next = (elm);                \
  277. } while (/*CONSTCOND*/0)
  278.  
  279. #define    STAILQ_REMOVE_HEAD(head, field) do {                \
  280.     if (((head)->stqh_first = (head)->stqh_first->field.stqe_next) == NULL) \
  281.         (head)->stqh_last = &(head)->stqh_first;            \
  282. } while (/*CONSTCOND*/0)
  283.  
  284. #define    STAILQ_REMOVE(head, elm, type, field) do {            \
  285.     if ((head)->stqh_first == (elm)) {                \
  286.         STAILQ_REMOVE_HEAD((head), field);            \
  287.     } else {                            \
  288.         struct type *curelm = (head)->stqh_first;        \
  289.         while (curelm->field.stqe_next != (elm))            \
  290.             curelm = curelm->field.stqe_next;        \
  291.         if ((curelm->field.stqe_next =                \
  292.             curelm->field.stqe_next->field.stqe_next) == NULL) \
  293.                 (head)->stqh_last = &(curelm)->field.stqe_next; \
  294.     }                                \
  295. } while (/*CONSTCOND*/0)
  296.  
  297. #define    STAILQ_FOREACH(var, head, field)                \
  298.     for ((var) = ((head)->stqh_first);                \
  299.         (var);                            \
  300.         (var) = ((var)->field.stqe_next))
  301.  
  302. /*
  303.  * Singly-linked Tail queue access methods.
  304.  */
  305. #define    STAILQ_EMPTY(head)    ((head)->stqh_first == NULL)
  306. #define    STAILQ_FIRST(head)    ((head)->stqh_first)
  307. #define    STAILQ_NEXT(elm, field)    ((elm)->field.stqe_next)
  308.  
  309.  
  310. /*
  311.  * Simple queue definitions.
  312.  */
  313. #define    SIMPLEQ_HEAD(name, type)                    \
  314. struct name {                                \
  315.     struct type *sqh_first;    /* first element */            \
  316.     struct type **sqh_last;    /* addr of last next element */        \
  317. }
  318.  
  319. #define    SIMPLEQ_HEAD_INITIALIZER(head)                    \
  320.     { NULL, &(head).sqh_first }
  321.  
  322. #define    SIMPLEQ_ENTRY(type)                        \
  323. struct {                                \
  324.     struct type *sqe_next;    /* next element */            \
  325. }
  326.  
  327. /*
  328.  * Simple queue functions.
  329.  */
  330. #define    SIMPLEQ_INIT(head) do {                        \
  331.     (head)->sqh_first = NULL;                    \
  332.     (head)->sqh_last = &(head)->sqh_first;                \
  333. } while (/*CONSTCOND*/0)
  334.  
  335. #define    SIMPLEQ_INSERT_HEAD(head, elm, field) do {            \
  336.     if (((elm)->field.sqe_next = (head)->sqh_first) == NULL)    \
  337.         (head)->sqh_last = &(elm)->field.sqe_next;        \
  338.     (head)->sqh_first = (elm);                    \
  339. } while (/*CONSTCOND*/0)
  340.  
  341. #define    SIMPLEQ_INSERT_TAIL(head, elm, field) do {            \
  342.     (elm)->field.sqe_next = NULL;                    \
  343.     *(head)->sqh_last = (elm);                    \
  344.     (head)->sqh_last = &(elm)->field.sqe_next;            \
  345. } while (/*CONSTCOND*/0)
  346.  
  347. #define    SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do {        \
  348.     if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
  349.         (head)->sqh_last = &(elm)->field.sqe_next;        \
  350.     (listelm)->field.sqe_next = (elm);                \
  351. } while (/*CONSTCOND*/0)
  352.  
  353. #define    SIMPLEQ_REMOVE_HEAD(head, field) do {                \
  354.     if (((head)->sqh_first = (head)->sqh_first->field.sqe_next) == NULL) \
  355.         (head)->sqh_last = &(head)->sqh_first;            \
  356. } while (/*CONSTCOND*/0)
  357.  
  358. #define    SIMPLEQ_REMOVE(head, elm, type, field) do {            \
  359.     if ((head)->sqh_first == (elm)) {                \
  360.         SIMPLEQ_REMOVE_HEAD((head), field);            \
  361.     } else {                            \
  362.         struct type *curelm = (head)->sqh_first;        \
  363.         while (curelm->field.sqe_next != (elm))            \
  364.             curelm = curelm->field.sqe_next;        \
  365.         if ((curelm->field.sqe_next =                \
  366.             curelm->field.sqe_next->field.sqe_next) == NULL) \
  367.                 (head)->sqh_last = &(curelm)->field.sqe_next; \
  368.     }                                \
  369. } while (/*CONSTCOND*/0)
  370.  
  371. #define    SIMPLEQ_FOREACH(var, head, field)                \
  372.     for ((var) = ((head)->sqh_first);                \
  373.         (var);                            \
  374.         (var) = ((var)->field.sqe_next))
  375.  
  376. /*
  377.  * Simple queue access methods.
  378.  */
  379. #define    SIMPLEQ_EMPTY(head)        ((head)->sqh_first == NULL)
  380. #define    SIMPLEQ_FIRST(head)        ((head)->sqh_first)
  381. #define    SIMPLEQ_NEXT(elm, field)    ((elm)->field.sqe_next)
  382.  
  383.  
  384. /*
  385.  * Tail queue definitions.
  386.  */
  387. #define    TAILQ_HEAD(name, type)                        \
  388. struct name {                                \
  389.     struct type *tqh_first;    /* first element */            \
  390.     struct type **tqh_last;    /* addr of last next element */        \
  391. }
  392.  
  393. #define    TAILQ_HEAD_INITIALIZER(head)                    \
  394.     { NULL, &(head).tqh_first }
  395.  
  396. #define    TAILQ_ENTRY(type)                        \
  397. struct {                                \
  398.     struct type *tqe_next;    /* next element */            \
  399.     struct type **tqe_prev;    /* address of previous next element */    \
  400. }
  401.  
  402. /*
  403.  * Tail queue functions.
  404.  */
  405. #if defined(_KERNEL) && defined(QUEUEDEBUG)
  406. #define    QUEUEDEBUG_TAILQ_INSERT_HEAD(head, elm, field)            \
  407.     if ((head)->tqh_first &&                    \
  408.         (head)->tqh_first->field.tqe_prev != &(head)->tqh_first)    \
  409.         panic("TAILQ_INSERT_HEAD %p %s:%d", (head), __FILE__, __LINE__);
  410. #define    QUEUEDEBUG_TAILQ_INSERT_TAIL(head, elm, field)            \
  411.     if (*(head)->tqh_last != NULL)                    \
  412.         panic("TAILQ_INSERT_TAIL %p %s:%d", (head), __FILE__, __LINE__);
  413. #define    QUEUEDEBUG_TAILQ_OP(elm, field)                    \
  414.     if ((elm)->field.tqe_next &&                    \
  415.         (elm)->field.tqe_next->field.tqe_prev !=            \
  416.         &(elm)->field.tqe_next)                    \
  417.         panic("TAILQ_* forw %p %s:%d", (elm), __FILE__, __LINE__);\
  418.     if (*(elm)->field.tqe_prev != (elm))                \
  419.         panic("TAILQ_* back %p %s:%d", (elm), __FILE__, __LINE__);
  420. #define    QUEUEDEBUG_TAILQ_PREREMOVE(head, elm, field)            \
  421.     if ((elm)->field.tqe_next == NULL &&                \
  422.         (head)->tqh_last != &(elm)->field.tqe_next)            \
  423.         panic("TAILQ_PREREMOVE head %p elm %p %s:%d",        \
  424.               (head), (elm), __FILE__, __LINE__);
  425. #define    QUEUEDEBUG_TAILQ_POSTREMOVE(elm, field)                \
  426.     (elm)->field.tqe_next = (void *)1L;                \
  427.     (elm)->field.tqe_prev = (void *)1L;
  428. #else
  429. #define    QUEUEDEBUG_TAILQ_INSERT_HEAD(head, elm, field)
  430. #define    QUEUEDEBUG_TAILQ_INSERT_TAIL(head, elm, field)
  431. #define    QUEUEDEBUG_TAILQ_OP(elm, field)
  432. #define    QUEUEDEBUG_TAILQ_PREREMOVE(head, elm, field)
  433. #define    QUEUEDEBUG_TAILQ_POSTREMOVE(elm, field)
  434. #endif
  435.  
  436. #define    TAILQ_INIT(head) do {                        \
  437.     (head)->tqh_first = NULL;                    \
  438.     (head)->tqh_last = &(head)->tqh_first;                \
  439. } while (/*CONSTCOND*/0)
  440.  
  441. #define    TAILQ_INSERT_HEAD(head, elm, field) do {            \
  442.     QUEUEDEBUG_TAILQ_INSERT_HEAD((head), (elm), field)        \
  443.     if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)    \
  444.         (head)->tqh_first->field.tqe_prev =            \
  445.             &(elm)->field.tqe_next;                \
  446.     else                                \
  447.         (head)->tqh_last = &(elm)->field.tqe_next;        \
  448.     (head)->tqh_first = (elm);                    \
  449.     (elm)->field.tqe_prev = &(head)->tqh_first;            \
  450. } while (/*CONSTCOND*/0)
  451.  
  452. #define    TAILQ_INSERT_TAIL(head, elm, field) do {            \
  453.     QUEUEDEBUG_TAILQ_INSERT_TAIL((head), (elm), field)        \
  454.     (elm)->field.tqe_next = NULL;                    \
  455.     (elm)->field.tqe_prev = (head)->tqh_last;            \
  456.     *(head)->tqh_last = (elm);                    \
  457.     (head)->tqh_last = &(elm)->field.tqe_next;            \
  458. } while (/*CONSTCOND*/0)
  459.  
  460. #define    TAILQ_INSERT_AFTER(head, listelm, elm, field) do {        \
  461.     QUEUEDEBUG_TAILQ_OP((listelm), field)                \
  462.     if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
  463.         (elm)->field.tqe_next->field.tqe_prev =         \
  464.             &(elm)->field.tqe_next;                \
  465.     else                                \
  466.         (head)->tqh_last = &(elm)->field.tqe_next;        \
  467.     (listelm)->field.tqe_next = (elm);                \
  468.     (elm)->field.tqe_prev = &(listelm)->field.tqe_next;        \
  469. } while (/*CONSTCOND*/0)
  470.  
  471. #define    TAILQ_INSERT_BEFORE(listelm, elm, field) do {            \
  472.     QUEUEDEBUG_TAILQ_OP((listelm), field)                \
  473.     (elm)->field.tqe_prev = (listelm)->field.tqe_prev;        \
  474.     (elm)->field.tqe_next = (listelm);                \
  475.     *(listelm)->field.tqe_prev = (elm);                \
  476.     (listelm)->field.tqe_prev = &(elm)->field.tqe_next;        \
  477. } while (/*CONSTCOND*/0)
  478.  
  479. #define    TAILQ_REMOVE(head, elm, field) do {                \
  480.     QUEUEDEBUG_TAILQ_PREREMOVE((head), (elm), field)        \
  481.     QUEUEDEBUG_TAILQ_OP((elm), field)                \
  482.     if (((elm)->field.tqe_next) != NULL)                \
  483.         (elm)->field.tqe_next->field.tqe_prev =         \
  484.             (elm)->field.tqe_prev;                \
  485.     else                                \
  486.         (head)->tqh_last = (elm)->field.tqe_prev;        \
  487.     *(elm)->field.tqe_prev = (elm)->field.tqe_next;            \
  488.     QUEUEDEBUG_TAILQ_POSTREMOVE((elm), field);            \
  489. } while (/*CONSTCOND*/0)
  490.  
  491. #define    TAILQ_FOREACH(var, head, field)                    \
  492.     for ((var) = ((head)->tqh_first);                \
  493.         (var);                            \
  494.         (var) = ((var)->field.tqe_next))
  495.  
  496. #define    TAILQ_FOREACH_REVERSE(var, head, headname, field)        \
  497.     for ((var) = (*(((struct headname *)((head)->tqh_last))->tqh_last));    \
  498.         (var);                            \
  499.         (var) = (*(((struct headname *)((var)->field.tqe_prev))->tqh_last)))
  500.  
  501. /*
  502.  * Tail queue access methods.
  503.  */
  504. #define    TAILQ_EMPTY(head)        ((head)->tqh_first == NULL)
  505. #define    TAILQ_FIRST(head)        ((head)->tqh_first)
  506. #define    TAILQ_NEXT(elm, field)        ((elm)->field.tqe_next)
  507.  
  508. #define    TAILQ_LAST(head, headname) \
  509.     (*(((struct headname *)((head)->tqh_last))->tqh_last))
  510. #define    TAILQ_PREV(elm, headname, field) \
  511.     (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
  512.  
  513.  
  514. /*
  515.  * Circular queue definitions.
  516.  */
  517. #define    CIRCLEQ_HEAD(name, type)                    \
  518. struct name {                                \
  519.     struct type *cqh_first;        /* first element */        \
  520.     struct type *cqh_last;        /* last element */        \
  521. }
  522.  
  523. #define    CIRCLEQ_HEAD_INITIALIZER(head)                    \
  524.     { (void *)&head, (void *)&head }
  525.  
  526. #define    CIRCLEQ_ENTRY(type)                        \
  527. struct {                                \
  528.     struct type *cqe_next;        /* next element */        \
  529.     struct type *cqe_prev;        /* previous element */        \
  530. }
  531.  
  532. /*
  533.  * Circular queue functions.
  534.  */
  535. #define    CIRCLEQ_INIT(head) do {                        \
  536.     (head)->cqh_first = (void *)(head);                \
  537.     (head)->cqh_last = (void *)(head);                \
  538. } while (/*CONSTCOND*/0)
  539.  
  540. #define    CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {        \
  541.     (elm)->field.cqe_next = (listelm)->field.cqe_next;        \
  542.     (elm)->field.cqe_prev = (listelm);                \
  543.     if ((listelm)->field.cqe_next == (void *)(head))        \
  544.         (head)->cqh_last = (elm);                \
  545.     else                                \
  546.         (listelm)->field.cqe_next->field.cqe_prev = (elm);    \
  547.     (listelm)->field.cqe_next = (elm);                \
  548. } while (/*CONSTCOND*/0)
  549.  
  550. #define    CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {        \
  551.     (elm)->field.cqe_next = (listelm);                \
  552.     (elm)->field.cqe_prev = (listelm)->field.cqe_prev;        \
  553.     if ((listelm)->field.cqe_prev == (void *)(head))        \
  554.         (head)->cqh_first = (elm);                \
  555.     else                                \
  556.         (listelm)->field.cqe_prev->field.cqe_next = (elm);    \
  557.     (listelm)->field.cqe_prev = (elm);                \
  558. } while (/*CONSTCOND*/0)
  559.  
  560. #define    CIRCLEQ_INSERT_HEAD(head, elm, field) do {            \
  561.     (elm)->field.cqe_next = (head)->cqh_first;            \
  562.     (elm)->field.cqe_prev = (void *)(head);                \
  563.     if ((head)->cqh_last == (void *)(head))                \
  564.         (head)->cqh_last = (elm);                \
  565.     else                                \
  566.         (head)->cqh_first->field.cqe_prev = (elm);        \
  567.     (head)->cqh_first = (elm);                    \
  568. } while (/*CONSTCOND*/0)
  569.  
  570. #define    CIRCLEQ_INSERT_TAIL(head, elm, field) do {            \
  571.     (elm)->field.cqe_next = (void *)(head);                \
  572.     (elm)->field.cqe_prev = (head)->cqh_last;            \
  573.     if ((head)->cqh_first == (void *)(head))            \
  574.         (head)->cqh_first = (elm);                \
  575.     else                                \
  576.         (head)->cqh_last->field.cqe_next = (elm);        \
  577.     (head)->cqh_last = (elm);                    \
  578. } while (/*CONSTCOND*/0)
  579.  
  580. #define    CIRCLEQ_REMOVE(head, elm, field) do {                \
  581.     if ((elm)->field.cqe_next == (void *)(head))            \
  582.         (head)->cqh_last = (elm)->field.cqe_prev;        \
  583.     else                                \
  584.         (elm)->field.cqe_next->field.cqe_prev =            \
  585.             (elm)->field.cqe_prev;                \
  586.     if ((elm)->field.cqe_prev == (void *)(head))            \
  587.         (head)->cqh_first = (elm)->field.cqe_next;        \
  588.     else                                \
  589.         (elm)->field.cqe_prev->field.cqe_next =            \
  590.             (elm)->field.cqe_next;                \
  591. } while (/*CONSTCOND*/0)
  592.  
  593. #define    CIRCLEQ_FOREACH(var, head, field)                \
  594.     for ((var) = ((head)->cqh_first);                \
  595.         (var) != (void *)(head);                \
  596.         (var) = ((var)->field.cqe_next))
  597.  
  598. #define    CIRCLEQ_FOREACH_REVERSE(var, head, field)            \
  599.     for ((var) = ((head)->cqh_last);                \
  600.         (var) != (void *)(head);                \
  601.         (var) = ((var)->field.cqe_prev))
  602.  
  603. /*
  604.  * Circular queue access methods.
  605.  */
  606. #define    CIRCLEQ_EMPTY(head)        ((head)->cqh_first == (void *)(head))
  607. #define    CIRCLEQ_FIRST(head)        ((head)->cqh_first)
  608. #define    CIRCLEQ_LAST(head)        ((head)->cqh_last)
  609. #define    CIRCLEQ_NEXT(elm, field)    ((elm)->field.cqe_next)
  610. #define    CIRCLEQ_PREV(elm, field)    ((elm)->field.cqe_prev)
  611.  
  612. #endif    /* !_SYS_QUEUE_H_ */
  613.