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Annotation of XNU/bsd/sys/queue.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * The contents of this file constitute Original Code as defined in and
        !             7:  * are subject to the Apple Public Source License Version 1.1 (the
        !             8:  * "License").  You may not use this file except in compliance with the
        !             9:  * License.  Please obtain a copy of the License at
        !            10:  * http://www.apple.com/publicsource and read it before using this file.
        !            11:  * 
        !            12:  * This Original Code and all software distributed under the License are
        !            13:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            14:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            15:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            16:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            17:  * License for the specific language governing rights and limitations
        !            18:  * under the License.
        !            19:  * 
        !            20:  * @APPLE_LICENSE_HEADER_END@
        !            21:  */
        !            22: /*
        !            23:  * Copyright (c) 1991, 1993
        !            24:  *     The Regents of the University of California.  All rights reserved.
        !            25:  *
        !            26:  * Redistribution and use in source and binary forms, with or without
        !            27:  * modification, are permitted provided that the following conditions
        !            28:  * are met:
        !            29:  * 1. Redistributions of source code must retain the above copyright
        !            30:  *    notice, this list of conditions and the following disclaimer.
        !            31:  * 2. Redistributions in binary form must reproduce the above copyright
        !            32:  *    notice, this list of conditions and the following disclaimer in the
        !            33:  *    documentation and/or other materials provided with the distribution.
        !            34:  * 3. All advertising materials mentioning features or use of this software
        !            35:  *    must display the following acknowledgement:
        !            36:  *     This product includes software developed by the University of
        !            37:  *     California, Berkeley and its contributors.
        !            38:  * 4. Neither the name of the University nor the names of its contributors
        !            39:  *    may be used to endorse or promote products derived from this software
        !            40:  *    without specific prior written permission.
        !            41:  *
        !            42:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            43:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            44:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            45:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            46:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            47:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            48:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            49:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            50:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            51:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            52:  * SUCH DAMAGE.
        !            53:  *
        !            54:  *     @(#)queue.h     8.5 (Berkeley) 8/20/94
        !            55:  */
        !            56: 
        !            57: #ifndef _SYS_QUEUE_H_
        !            58: #define        _SYS_QUEUE_H_
        !            59: 
        !            60: /*
        !            61:  * This file defines five types of data structures: singly-linked lists,
        !            62:  * slingly-linked tail queues, lists, tail queues, and circular queues.
        !            63:  *
        !            64:  * A singly-linked list is headed by a single forward pointer. The elements
        !            65:  * are singly linked for minimum space and pointer manipulation overhead at
        !            66:  * the expense of O(n) removal for arbitrary elements. New elements can be
        !            67:  * added to the list after an existing element or at the head of the list.
        !            68:  * Elements being removed from the head of the list should use the explicit
        !            69:  * macro for this purpose for optimum efficiency. A singly-linked list may
        !            70:  * only be traversed in the forward direction.  Singly-linked lists are ideal
        !            71:  * for applications with large datasets and few or no removals or for
        !            72:  * implementing a LIFO queue.
        !            73:  *
        !            74:  * A singly-linked tail queue is headed by a pair of pointers, one to the
        !            75:  * head of the list and the other to the tail of the list. The elements are
        !            76:  * singly linked for minimum space and pointer manipulation overhead at the
        !            77:  * expense of O(n) removal for arbitrary elements. New elements can be added
        !            78:  * to the list after an existing element, at the head of the list, or at the
        !            79:  * end of the list. Elements being removed from the head of the tail queue
        !            80:  * should use the explicit macro for this purpose for optimum efficiency.
        !            81:  * A singly-linked tail queue may only be traversed in the forward direction.
        !            82:  * Singly-linked tail queues are ideal for applications with large datasets
        !            83:  * and few or no removals or for implementing a FIFO queue.
        !            84:  *
        !            85:  * A list is headed by a single forward pointer (or an array of forward
        !            86:  * pointers for a hash table header). The elements are doubly linked
        !            87:  * so that an arbitrary element can be removed without a need to
        !            88:  * traverse the list. New elements can be added to the list before
        !            89:  * or after an existing element or at the head of the list. A list
        !            90:  * may only be traversed in the forward direction.
        !            91:  *
        !            92:  * A tail queue is headed by a pair of pointers, one to the head of the
        !            93:  * list and the other to the tail of the list. The elements are doubly
        !            94:  * linked so that an arbitrary element can be removed without a need to
        !            95:  * traverse the list. New elements can be added to the list before or
        !            96:  * after an existing element, at the head of the list, or at the end of
        !            97:  * the list. A tail queue may only be traversed in the forward direction.
        !            98:  *
        !            99:  * A circle queue is headed by a pair of pointers, one to the head of the
        !           100:  * list and the other to the tail of the list. The elements are doubly
        !           101:  * linked so that an arbitrary element can be removed without a need to
        !           102:  * traverse the list. New elements can be added to the list before or after
        !           103:  * an existing element, at the head of the list, or at the end of the list.
        !           104:  * A circle queue may be traversed in either direction, but has a more
        !           105:  * complex end of list detection.
        !           106:  *
        !           107:  * For details on the use of these macros, see the queue(3) manual page.
        !           108:  *
        !           109:  *
        !           110:  *                     SLIST   LIST    STAILQ  TAILQ   CIRCLEQ
        !           111:  * _HEAD               +       +       +       +       +
        !           112:  * _ENTRY              +       +       +       +       +
        !           113:  * _INIT               +       +       +       +       +
        !           114:  * _EMPTY              +       +       +       +       +
        !           115:  * _FIRST              +       +       +       +       +
        !           116:  * _NEXT               +       +       +       +       +
        !           117:  * _PREV               -       -       -       +       +
        !           118:  * _LAST               -       -       +       +       +
        !           119:  * _FOREACH            +       +       -       +       +
        !           120:  * _INSERT_HEAD                +       +       +       +       +
        !           121:  * _INSERT_BEFORE      -       +       -       +       +
        !           122:  * _INSERT_AFTER       +       +       +       +       +
        !           123:  * _INSERT_TAIL                -       -       +       +       +
        !           124:  * _REMOVE_HEAD                +       -       +       -       -
        !           125:  * _REMOVE             +       +       +       +       +
        !           126:  *
        !           127:  */
        !           128: 
        !           129: /*
        !           130:  * Singly-linked List definitions.
        !           131:  */
        !           132: #define SLIST_HEAD(name, type)                                         \
        !           133: struct name {                                                          \
        !           134:        struct type *slh_first; /* first element */                     \
        !           135: }
        !           136:  
        !           137: #define SLIST_ENTRY(type)                                              \
        !           138: struct {                                                               \
        !           139:        struct type *sle_next;  /* next element */                      \
        !           140: }
        !           141:  
        !           142: /*
        !           143:  * Singly-linked List functions.
        !           144:  */
        !           145: #define        SLIST_EMPTY(head)       ((head)->slh_first == NULL)
        !           146: 
        !           147: #define        SLIST_FIRST(head)       ((head)->slh_first)
        !           148: 
        !           149: #define SLIST_FOREACH(var, head, field)                                        \
        !           150:        for((var) = (head)->slh_first; (var); (var) = (var)->field.sle_next)
        !           151: 
        !           152: #define SLIST_INIT(head) {                                             \
        !           153:        (head)->slh_first = NULL;                                       \
        !           154: }
        !           155: 
        !           156: #define SLIST_INSERT_AFTER(slistelm, elm, field) do {                  \
        !           157:        (elm)->field.sle_next = (slistelm)->field.sle_next;             \
        !           158:        (slistelm)->field.sle_next = (elm);                             \
        !           159: } while (0)
        !           160: 
        !           161: #define SLIST_INSERT_HEAD(head, elm, field) do {                       \
        !           162:        (elm)->field.sle_next = (head)->slh_first;                      \
        !           163:        (head)->slh_first = (elm);                                      \
        !           164: } while (0)
        !           165: 
        !           166: #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
        !           167: 
        !           168: #define SLIST_REMOVE_HEAD(head, field) do {                            \
        !           169:        (head)->slh_first = (head)->slh_first->field.sle_next;          \
        !           170: } while (0)
        !           171: 
        !           172: #define SLIST_REMOVE(head, elm, type, field) do {                      \
        !           173:        if ((head)->slh_first == (elm)) {                               \
        !           174:                SLIST_REMOVE_HEAD((head), field);                       \
        !           175:        }                                                               \
        !           176:        else {                                                          \
        !           177:                struct type *curelm = (head)->slh_first;                \
        !           178:                while( curelm->field.sle_next != (elm) )                \
        !           179:                        curelm = curelm->field.sle_next;                \
        !           180:                curelm->field.sle_next =                                \
        !           181:                    curelm->field.sle_next->field.sle_next;             \
        !           182:        }                                                               \
        !           183: } while (0)
        !           184: 
        !           185: /*
        !           186:  * Singly-linked Tail queue definitions.
        !           187:  */
        !           188: #define STAILQ_HEAD(name, type)                                                \
        !           189: struct name {                                                          \
        !           190:        struct type *stqh_first;/* first element */                     \
        !           191:        struct type **stqh_last;/* addr of last next element */         \
        !           192: }
        !           193: 
        !           194: #define STAILQ_HEAD_INITIALIZER(head)                                  \
        !           195:        { NULL, &(head).stqh_first }
        !           196: 
        !           197: #define STAILQ_ENTRY(type)                                             \
        !           198: struct {                                                               \
        !           199:        struct type *stqe_next; /* next element */                      \
        !           200: }
        !           201: 
        !           202: /*
        !           203:  * Singly-linked Tail queue functions.
        !           204:  */
        !           205: #define STAILQ_EMPTY(head) ((head)->stqh_first == NULL)
        !           206: 
        !           207: #define        STAILQ_INIT(head) do {                                          \
        !           208:        (head)->stqh_first = NULL;                                      \
        !           209:        (head)->stqh_last = &(head)->stqh_first;                        \
        !           210: } while (0)
        !           211: 
        !           212: #define STAILQ_FIRST(head)     ((head)->stqh_first)
        !           213: #define STAILQ_LAST(head)      (*(head)->stqh_last)
        !           214: 
        !           215: #define STAILQ_INSERT_HEAD(head, elm, field) do {                      \
        !           216:        if (((elm)->field.stqe_next = (head)->stqh_first) == NULL)      \
        !           217:                (head)->stqh_last = &(elm)->field.stqe_next;            \
        !           218:        (head)->stqh_first = (elm);                                     \
        !           219: } while (0)
        !           220: 
        !           221: #define STAILQ_INSERT_TAIL(head, elm, field) do {                      \
        !           222:        (elm)->field.stqe_next = NULL;                                  \
        !           223:        *(head)->stqh_last = (elm);                                     \
        !           224:        (head)->stqh_last = &(elm)->field.stqe_next;                    \
        !           225: } while (0)
        !           226: 
        !           227: #define STAILQ_INSERT_AFTER(head, tqelm, elm, field) do {              \
        !           228:        if (((elm)->field.stqe_next = (tqelm)->field.stqe_next) == NULL)\
        !           229:                (head)->stqh_last = &(elm)->field.stqe_next;            \
        !           230:        (tqelm)->field.stqe_next = (elm);                               \
        !           231: } while (0)
        !           232: 
        !           233: #define STAILQ_NEXT(elm, field)        ((elm)->field.stqe_next)
        !           234: 
        !           235: #define STAILQ_REMOVE_HEAD(head, field) do {                           \
        !           236:        if (((head)->stqh_first =                                       \
        !           237:             (head)->stqh_first->field.stqe_next) == NULL)              \
        !           238:                (head)->stqh_last = &(head)->stqh_first;                \
        !           239: } while (0)
        !           240: 
        !           241: #define STAILQ_REMOVE_HEAD_UNTIL(head, elm, field) do {                        \
        !           242:        if (((head)->stqh_first = (elm)->field.stqe_next) == NULL)      \
        !           243:                (head)->stqh_last = &(head)->stqh_first;                \
        !           244: } while (0)
        !           245: 
        !           246: 
        !           247: #define STAILQ_REMOVE(head, elm, type, field) do {                     \
        !           248:        if ((head)->stqh_first == (elm)) {                              \
        !           249:                STAILQ_REMOVE_HEAD(head, field);                        \
        !           250:        }                                                               \
        !           251:        else {                                                          \
        !           252:                struct type *curelm = (head)->stqh_first;               \
        !           253:                while( curelm->field.stqe_next != (elm) )               \
        !           254:                        curelm = curelm->field.stqe_next;               \
        !           255:                if((curelm->field.stqe_next =                           \
        !           256:                    curelm->field.stqe_next->field.stqe_next) == NULL)  \
        !           257:                        (head)->stqh_last = &(curelm)->field.stqe_next; \
        !           258:        }                                                               \
        !           259: } while (0)
        !           260: 
        !           261: /*
        !           262:  * List definitions.
        !           263:  */
        !           264: #define LIST_HEAD(name, type)                                          \
        !           265: struct name {                                                          \
        !           266:        struct type *lh_first;  /* first element */                     \
        !           267: }
        !           268: 
        !           269: #define LIST_HEAD_INITIALIZER(head)                                    \
        !           270:        { NULL }
        !           271: 
        !           272: #define LIST_ENTRY(type)                                               \
        !           273: struct {                                                               \
        !           274:        struct type *le_next;   /* next element */                      \
        !           275:        struct type **le_prev;  /* address of previous next element */  \
        !           276: }
        !           277: 
        !           278: /*
        !           279:  * List functions.
        !           280:  */
        !           281: 
        !           282: #define        LIST_EMPTY(head) ((head)->lh_first == NULL)
        !           283: 
        !           284: #define LIST_FIRST(head)       ((head)->lh_first)
        !           285: 
        !           286: #define LIST_FOREACH(var, head, field)                                 \
        !           287:        for((var) = (head)->lh_first; (var); (var) = (var)->field.le_next)
        !           288: 
        !           289: #define        LIST_INIT(head) do {                                            \
        !           290:        (head)->lh_first = NULL;                                        \
        !           291: } while (0)
        !           292: 
        !           293: #define LIST_INSERT_AFTER(listelm, elm, field) do {                    \
        !           294:        if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
        !           295:                (listelm)->field.le_next->field.le_prev =               \
        !           296:                    &(elm)->field.le_next;                              \
        !           297:        (listelm)->field.le_next = (elm);                               \
        !           298:        (elm)->field.le_prev = &(listelm)->field.le_next;               \
        !           299: } while (0)
        !           300: 
        !           301: #define LIST_INSERT_BEFORE(listelm, elm, field) do {                   \
        !           302:        (elm)->field.le_prev = (listelm)->field.le_prev;                \
        !           303:        (elm)->field.le_next = (listelm);                               \
        !           304:        *(listelm)->field.le_prev = (elm);                              \
        !           305:        (listelm)->field.le_prev = &(elm)->field.le_next;               \
        !           306: } while (0)
        !           307: 
        !           308: #define LIST_INSERT_HEAD(head, elm, field) do {                                \
        !           309:        if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
        !           310:                (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
        !           311:        (head)->lh_first = (elm);                                       \
        !           312:        (elm)->field.le_prev = &(head)->lh_first;                       \
        !           313: } while (0)
        !           314: 
        !           315: #define LIST_NEXT(elm, field)  ((elm)->field.le_next)
        !           316: 
        !           317: #define LIST_REMOVE(elm, field) do {                                   \
        !           318:        if ((elm)->field.le_next != NULL)                               \
        !           319:                (elm)->field.le_next->field.le_prev =                   \
        !           320:                    (elm)->field.le_prev;                               \
        !           321:        *(elm)->field.le_prev = (elm)->field.le_next;                   \
        !           322: } while (0)
        !           323: 
        !           324: /*
        !           325:  * Tail queue definitions.
        !           326:  */
        !           327: #define TAILQ_HEAD(name, type)                                         \
        !           328: struct name {                                                          \
        !           329:        struct type *tqh_first; /* first element */                     \
        !           330:        struct type **tqh_last; /* addr of last next element */         \
        !           331: }
        !           332: 
        !           333: #define TAILQ_HEAD_INITIALIZER(head)                                   \
        !           334:        { NULL, &(head).tqh_first }
        !           335: 
        !           336: #define TAILQ_ENTRY(type)                                              \
        !           337: struct {                                                               \
        !           338:        struct type *tqe_next;  /* next element */                      \
        !           339:        struct type **tqe_prev; /* address of previous next element */  \
        !           340: }
        !           341: 
        !           342: /*
        !           343:  * Tail queue functions.
        !           344:  */
        !           345: #define        TAILQ_EMPTY(head) ((head)->tqh_first == NULL)
        !           346: 
        !           347: #define TAILQ_FOREACH(var, head, field)                                        \
        !           348:        for (var = TAILQ_FIRST(head); var; var = TAILQ_NEXT(var, field))
        !           349: 
        !           350: #define TAILQ_FOREACH_REVERSE(var, head, field, headname)                                      \
        !           351:        for (var = TAILQ_LAST(head, headname);                 \
        !           352:               var; var = TAILQ_PREV(var, headname, field))
        !           353: 
        !           354: #define        TAILQ_FIRST(head) ((head)->tqh_first)
        !           355: 
        !           356: #define        TAILQ_LAST(head, headname) \
        !           357:        (*(((struct headname *)((head)->tqh_last))->tqh_last))
        !           358: 
        !           359: #define        TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
        !           360: 
        !           361: #define TAILQ_PREV(elm, headname, field) \
        !           362:        (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
        !           363: 
        !           364: #define        TAILQ_INIT(head) do {                                           \
        !           365:        (head)->tqh_first = NULL;                                       \
        !           366:        (head)->tqh_last = &(head)->tqh_first;                          \
        !           367: } while (0)
        !           368: 
        !           369: #define TAILQ_INSERT_HEAD(head, elm, field) do {                       \
        !           370:        if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
        !           371:                (head)->tqh_first->field.tqe_prev =                     \
        !           372:                    &(elm)->field.tqe_next;                             \
        !           373:        else                                                            \
        !           374:                (head)->tqh_last = &(elm)->field.tqe_next;              \
        !           375:        (head)->tqh_first = (elm);                                      \
        !           376:        (elm)->field.tqe_prev = &(head)->tqh_first;                     \
        !           377: } while (0)
        !           378: 
        !           379: #define TAILQ_INSERT_TAIL(head, elm, field) do {                       \
        !           380:        (elm)->field.tqe_next = NULL;                                   \
        !           381:        (elm)->field.tqe_prev = (head)->tqh_last;                       \
        !           382:        *(head)->tqh_last = (elm);                                      \
        !           383:        (head)->tqh_last = &(elm)->field.tqe_next;                      \
        !           384: } while (0)
        !           385: 
        !           386: #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do {             \
        !           387:        if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
        !           388:                (elm)->field.tqe_next->field.tqe_prev =                 \
        !           389:                    &(elm)->field.tqe_next;                             \
        !           390:        else                                                            \
        !           391:                (head)->tqh_last = &(elm)->field.tqe_next;              \
        !           392:        (listelm)->field.tqe_next = (elm);                              \
        !           393:        (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
        !           394: } while (0)
        !           395: 
        !           396: #define TAILQ_INSERT_BEFORE(listelm, elm, field) do {                  \
        !           397:        (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
        !           398:        (elm)->field.tqe_next = (listelm);                              \
        !           399:        *(listelm)->field.tqe_prev = (elm);                             \
        !           400:        (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
        !           401: } while (0)
        !           402: 
        !           403: #define TAILQ_REMOVE(head, elm, field) do {                            \
        !           404:        if (((elm)->field.tqe_next) != NULL)                            \
        !           405:                (elm)->field.tqe_next->field.tqe_prev =                 \
        !           406:                    (elm)->field.tqe_prev;                              \
        !           407:        else                                                            \
        !           408:                (head)->tqh_last = (elm)->field.tqe_prev;               \
        !           409:        *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
        !           410: } while (0)
        !           411: 
        !           412: /*
        !           413:  * Circular queue definitions.
        !           414:  */
        !           415: #define CIRCLEQ_HEAD(name, type)                                       \
        !           416: struct name {                                                          \
        !           417:        struct type *cqh_first;         /* first element */             \
        !           418:        struct type *cqh_last;          /* last element */              \
        !           419: }
        !           420: 
        !           421: #define CIRCLEQ_ENTRY(type)                                            \
        !           422: struct {                                                               \
        !           423:        struct type *cqe_next;          /* next element */              \
        !           424:        struct type *cqe_prev;          /* previous element */          \
        !           425: }
        !           426: 
        !           427: /*
        !           428:  * Circular queue functions.
        !           429:  */
        !           430: #define CIRCLEQ_EMPTY(head) ((head)->cqh_first == (void *)(head))
        !           431: 
        !           432: #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
        !           433: 
        !           434: #define CIRCLEQ_FOREACH(var, head, field)                              \
        !           435:        for((var) = (head)->cqh_first;                                  \
        !           436:            (var) != (void *)(head);                                    \
        !           437:            (var) = (var)->field.cqe_next)
        !           438: 
        !           439: #define        CIRCLEQ_INIT(head) do {                                         \
        !           440:        (head)->cqh_first = (void *)(head);                             \
        !           441:        (head)->cqh_last = (void *)(head);                              \
        !           442: } while (0)
        !           443: 
        !           444: #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do {           \
        !           445:        (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
        !           446:        (elm)->field.cqe_prev = (listelm);                              \
        !           447:        if ((listelm)->field.cqe_next == (void *)(head))                \
        !           448:                (head)->cqh_last = (elm);                               \
        !           449:        else                                                            \
        !           450:                (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
        !           451:        (listelm)->field.cqe_next = (elm);                              \
        !           452: } while (0)
        !           453: 
        !           454: #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do {          \
        !           455:        (elm)->field.cqe_next = (listelm);                              \
        !           456:        (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
        !           457:        if ((listelm)->field.cqe_prev == (void *)(head))                \
        !           458:                (head)->cqh_first = (elm);                              \
        !           459:        else                                                            \
        !           460:                (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
        !           461:        (listelm)->field.cqe_prev = (elm);                              \
        !           462: } while (0)
        !           463: 
        !           464: #define CIRCLEQ_INSERT_HEAD(head, elm, field) do {                     \
        !           465:        (elm)->field.cqe_next = (head)->cqh_first;                      \
        !           466:        (elm)->field.cqe_prev = (void *)(head);                         \
        !           467:        if ((head)->cqh_last == (void *)(head))                         \
        !           468:                (head)->cqh_last = (elm);                               \
        !           469:        else                                                            \
        !           470:                (head)->cqh_first->field.cqe_prev = (elm);              \
        !           471:        (head)->cqh_first = (elm);                                      \
        !           472: } while (0)
        !           473: 
        !           474: #define CIRCLEQ_INSERT_TAIL(head, elm, field) do {                     \
        !           475:        (elm)->field.cqe_next = (void *)(head);                         \
        !           476:        (elm)->field.cqe_prev = (head)->cqh_last;                       \
        !           477:        if ((head)->cqh_first == (void *)(head))                        \
        !           478:                (head)->cqh_first = (elm);                              \
        !           479:        else                                                            \
        !           480:                (head)->cqh_last->field.cqe_next = (elm);               \
        !           481:        (head)->cqh_last = (elm);                                       \
        !           482: } while (0)
        !           483: 
        !           484: #define CIRCLEQ_LAST(head) ((head)->cqh_last)
        !           485: 
        !           486: #define CIRCLEQ_NEXT(elm,field) ((elm)->field.cqe_next)
        !           487: 
        !           488: #define CIRCLEQ_PREV(elm,field) ((elm)->field.cqe_prev)
        !           489: 
        !           490: #define        CIRCLEQ_REMOVE(head, elm, field) do {                           \
        !           491:        if ((elm)->field.cqe_next == (void *)(head))                    \
        !           492:                (head)->cqh_last = (elm)->field.cqe_prev;               \
        !           493:        else                                                            \
        !           494:                (elm)->field.cqe_next->field.cqe_prev =                 \
        !           495:                    (elm)->field.cqe_prev;                              \
        !           496:        if ((elm)->field.cqe_prev == (void *)(head))                    \
        !           497:                (head)->cqh_first = (elm)->field.cqe_next;              \
        !           498:        else                                                            \
        !           499:                (elm)->field.cqe_prev->field.cqe_next =                 \
        !           500:                    (elm)->field.cqe_next;                              \
        !           501: } while (0)
        !           502: 
        !           503: #ifdef KERNEL
        !           504: 
        !           505: #if NOTFB31
        !           506: 
        !           507: /*
        !           508:  * XXX insque() and remque() are an old way of handling certain queues.
        !           509:  * They bogusly assumes that all queue heads look alike.
        !           510:  */
        !           511: 
        !           512: struct quehead {
        !           513:        struct quehead *qh_link;
        !           514:        struct quehead *qh_rlink;
        !           515: };
        !           516: 
        !           517: #ifdef __GNUC__
        !           518: 
        !           519: static __inline void
        !           520: insque(void *a, void *b)
        !           521: {
        !           522:        struct quehead *element = a, *head = b;
        !           523: 
        !           524:        element->qh_link = head->qh_link;
        !           525:        element->qh_rlink = head;
        !           526:        head->qh_link = element;
        !           527:        element->qh_link->qh_rlink = element;
        !           528: }
        !           529: 
        !           530: static __inline void
        !           531: remque(void *a)
        !           532: {
        !           533:        struct quehead *element = a;
        !           534: 
        !           535:        element->qh_link->qh_rlink = element->qh_rlink;
        !           536:        element->qh_rlink->qh_link = element->qh_link;
        !           537:        element->qh_rlink = 0;
        !           538: }
        !           539: 
        !           540: #else /* !__GNUC__ */
        !           541: 
        !           542: void   insque __P((void *a, void *b));
        !           543: void   remque __P((void *a));
        !           544: 
        !           545: #endif /* __GNUC__ */
        !           546: 
        !           547: #endif
        !           548: #endif /* KERNEL */
        !           549: 
        !           550: #endif /* !_SYS_QUEUE_H_ */

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