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

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
        !            26: /* 
        !            27:  * Copyright (c) 1991, 1993
        !            28:  *     The Regents of the University of California.  All rights reserved.
        !            29:  *
        !            30:  * Redistribution and use in source and binary forms, with or without
        !            31:  * modification, are permitted provided that the following conditions
        !            32:  * are met:
        !            33:  * 1. Redistributions of source code must retain the above copyright
        !            34:  *    notice, this list of conditions and the following disclaimer.
        !            35:  * 2. Redistributions in binary form must reproduce the above copyright
        !            36:  *    notice, this list of conditions and the following disclaimer in the
        !            37:  *    documentation and/or other materials provided with the distribution.
        !            38:  * 3. All advertising materials mentioning features or use of this software
        !            39:  *    must display the following acknowledgement:
        !            40:  *     This product includes software developed by the University of
        !            41:  *     California, Berkeley and its contributors.
        !            42:  * 4. Neither the name of the University nor the names of its contributors
        !            43:  *    may be used to endorse or promote products derived from this software
        !            44:  *    without specific prior written permission.
        !            45:  *
        !            46:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            47:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            48:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            49:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            50:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            51:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            52:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            53:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            54:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            55:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            56:  * SUCH DAMAGE.
        !            57:  *
        !            58:  *     @(#)queue.h     8.5 (Berkeley) 8/20/94
        !            59:  */
        !            60: 
        !            61: #ifndef        _SYS_QUEUE_H_
        !            62: #define        _SYS_QUEUE_H_
        !            63: 
        !            64: /*
        !            65:  * This file defines three types of data structures: lists, tail queues,
        !            66:  * and circular queues.
        !            67:  *
        !            68:  * A list is headed by a single forward pointer (or an array of forward
        !            69:  * pointers for a hash table header). The elements are doubly linked
        !            70:  * so that an arbitrary element can be removed without a need to
        !            71:  * traverse the list. New elements can be added to the list before
        !            72:  * or after an existing element or at the head of the list. A list
        !            73:  * may only be traversed in the forward direction.
        !            74:  *
        !            75:  * A tail queue is headed by a pair of pointers, one to the head of the
        !            76:  * list and the other to the tail of the list. The elements are doubly
        !            77:  * linked so that an arbitrary element can be removed without a need to
        !            78:  * traverse the list. New elements can be added to the list before or
        !            79:  * after an existing element, at the head of the list, or at the end of
        !            80:  * the list. A tail queue may only be traversed in the forward direction.
        !            81:  *
        !            82:  * A circle queue is headed by a pair of pointers, one to the head of the
        !            83:  * list and the other to the tail of the list. The elements are doubly
        !            84:  * linked so that an arbitrary element can be removed without a need to
        !            85:  * traverse the list. New elements can be added to the list before or after
        !            86:  * an existing element, at the head of the list, or at the end of the list.
        !            87:  * A circle queue may be traversed in either direction, but has a more
        !            88:  * complex end of list detection.
        !            89:  *
        !            90:  * For details on the use of these macros, see the queue(3) manual page.
        !            91:  */
        !            92: 
        !            93: /*
        !            94:  * List definitions.
        !            95:  */
        !            96: #define LIST_HEAD(name, type)                                          \
        !            97: struct name {                                                          \
        !            98:        struct type *lh_first;  /* first element */                     \
        !            99: }
        !           100: 
        !           101: #define LIST_ENTRY(type)                                               \
        !           102: struct {                                                               \
        !           103:        struct type *le_next;   /* next element */                      \
        !           104:        struct type **le_prev;  /* address of previous next element */  \
        !           105: }
        !           106: 
        !           107: /*
        !           108:  * List functions.
        !           109:  */
        !           110: #define        LIST_INIT(head) {                                               \
        !           111:        (head)->lh_first = NULL;                                        \
        !           112: }
        !           113: 
        !           114: #define LIST_INSERT_AFTER(listelm, elm, field) {                       \
        !           115:        if (((elm)->field.le_next = (listelm)->field.le_next) != NULL)  \
        !           116:                (listelm)->field.le_next->field.le_prev =               \
        !           117:                    &(elm)->field.le_next;                              \
        !           118:        (listelm)->field.le_next = (elm);                               \
        !           119:        (elm)->field.le_prev = &(listelm)->field.le_next;               \
        !           120: }
        !           121: 
        !           122: #define        LIST_INSERT_BEFORE(listelm, elm, field) {                       \
        !           123:        (elm)->field.le_prev = (listelm)->field.le_prev;                \
        !           124:        (elm)->field.le_next = (listelm);                               \
        !           125:        *(listelm)->field.le_prev = (elm);                              \
        !           126:        (listelm)->field.le_prev = &(elm)->field.le_next;               \
        !           127: }
        !           128: 
        !           129: #define LIST_INSERT_HEAD(head, elm, field) {                           \
        !           130:        if (((elm)->field.le_next = (head)->lh_first) != NULL)          \
        !           131:                (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
        !           132:        (head)->lh_first = (elm);                                       \
        !           133:        (elm)->field.le_prev = &(head)->lh_first;                       \
        !           134: }
        !           135: 
        !           136: #define LIST_REMOVE(elm, field) {                                      \
        !           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: }
        !           142: 
        !           143: /*
        !           144:  * Tail queue definitions.
        !           145:  */
        !           146: #define TAILQ_HEAD(name, type)                                         \
        !           147: struct name {                                                          \
        !           148:        struct type *tqh_first; /* first element */                     \
        !           149:        struct type **tqh_last; /* addr of last next element */         \
        !           150: }
        !           151: 
        !           152: #define TAILQ_ENTRY(type)                                              \
        !           153: struct {                                                               \
        !           154:        struct type *tqe_next;  /* next element */                      \
        !           155:        struct type **tqe_prev; /* address of previous next element */  \
        !           156: }
        !           157: 
        !           158: /*
        !           159:  * Tail queue functions.
        !           160:  */
        !           161: #define        TAILQ_INIT(head) {                                              \
        !           162:        (head)->tqh_first = NULL;                                       \
        !           163:        (head)->tqh_last = &(head)->tqh_first;                          \
        !           164: }
        !           165: 
        !           166: #define TAILQ_INSERT_HEAD(head, elm, field) {                          \
        !           167:        if (((elm)->field.tqe_next = (head)->tqh_first) != NULL)        \
        !           168:                (head)->tqh_first->field.tqe_prev =                     \
        !           169:                    &(elm)->field.tqe_next;                             \
        !           170:        else                                                            \
        !           171:                (head)->tqh_last = &(elm)->field.tqe_next;              \
        !           172:        (head)->tqh_first = (elm);                                      \
        !           173:        (elm)->field.tqe_prev = &(head)->tqh_first;                     \
        !           174: }
        !           175: 
        !           176: #define TAILQ_INSERT_TAIL(head, elm, field) {                          \
        !           177:        (elm)->field.tqe_next = NULL;                                   \
        !           178:        (elm)->field.tqe_prev = (head)->tqh_last;                       \
        !           179:        *(head)->tqh_last = (elm);                                      \
        !           180:        (head)->tqh_last = &(elm)->field.tqe_next;                      \
        !           181: }
        !           182: 
        !           183: #define TAILQ_INSERT_AFTER(head, listelm, elm, field) {                        \
        !           184:        if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
        !           185:                (elm)->field.tqe_next->field.tqe_prev =                 \
        !           186:                    &(elm)->field.tqe_next;                             \
        !           187:        else                                                            \
        !           188:                (head)->tqh_last = &(elm)->field.tqe_next;              \
        !           189:        (listelm)->field.tqe_next = (elm);                              \
        !           190:        (elm)->field.tqe_prev = &(listelm)->field.tqe_next;             \
        !           191: }
        !           192: 
        !           193: #define        TAILQ_INSERT_BEFORE(listelm, elm, field) {                      \
        !           194:        (elm)->field.tqe_prev = (listelm)->field.tqe_prev;              \
        !           195:        (elm)->field.tqe_next = (listelm);                              \
        !           196:        *(listelm)->field.tqe_prev = (elm);                             \
        !           197:        (listelm)->field.tqe_prev = &(elm)->field.tqe_next;             \
        !           198: }
        !           199: 
        !           200: #define TAILQ_REMOVE(head, elm, field) {                               \
        !           201:        if (((elm)->field.tqe_next) != NULL)                            \
        !           202:                (elm)->field.tqe_next->field.tqe_prev =                 \
        !           203:                    (elm)->field.tqe_prev;                              \
        !           204:        else                                                            \
        !           205:                (head)->tqh_last = (elm)->field.tqe_prev;               \
        !           206:        *(elm)->field.tqe_prev = (elm)->field.tqe_next;                 \
        !           207: }
        !           208: 
        !           209: /*
        !           210:  * Circular queue definitions.
        !           211:  */
        !           212: #define CIRCLEQ_HEAD(name, type)                                       \
        !           213: struct name {                                                          \
        !           214:        struct type *cqh_first;         /* first element */             \
        !           215:        struct type *cqh_last;          /* last element */              \
        !           216: }
        !           217: 
        !           218: #define CIRCLEQ_ENTRY(type)                                            \
        !           219: struct {                                                               \
        !           220:        struct type *cqe_next;          /* next element */              \
        !           221:        struct type *cqe_prev;          /* previous element */          \
        !           222: }
        !           223: 
        !           224: /*
        !           225:  * Circular queue functions.
        !           226:  */
        !           227: #define        CIRCLEQ_INIT(head) {                                            \
        !           228:        (head)->cqh_first = (void *)(head);                             \
        !           229:        (head)->cqh_last = (void *)(head);                              \
        !           230: }
        !           231: 
        !           232: #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) {              \
        !           233:        (elm)->field.cqe_next = (listelm)->field.cqe_next;              \
        !           234:        (elm)->field.cqe_prev = (listelm);                              \
        !           235:        if ((listelm)->field.cqe_next == (void *)(head))                \
        !           236:                (head)->cqh_last = (elm);                               \
        !           237:        else                                                            \
        !           238:                (listelm)->field.cqe_next->field.cqe_prev = (elm);      \
        !           239:        (listelm)->field.cqe_next = (elm);                              \
        !           240: }
        !           241: 
        !           242: #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) {             \
        !           243:        (elm)->field.cqe_next = (listelm);                              \
        !           244:        (elm)->field.cqe_prev = (listelm)->field.cqe_prev;              \
        !           245:        if ((listelm)->field.cqe_prev == (void *)(head))                \
        !           246:                (head)->cqh_first = (elm);                              \
        !           247:        else                                                            \
        !           248:                (listelm)->field.cqe_prev->field.cqe_next = (elm);      \
        !           249:        (listelm)->field.cqe_prev = (elm);                              \
        !           250: }
        !           251: 
        !           252: #define CIRCLEQ_INSERT_HEAD(head, elm, field) {                                \
        !           253:        (elm)->field.cqe_next = (head)->cqh_first;                      \
        !           254:        (elm)->field.cqe_prev = (void *)(head);                         \
        !           255:        if ((head)->cqh_last == (void *)(head))                         \
        !           256:                (head)->cqh_last = (elm);                               \
        !           257:        else                                                            \
        !           258:                (head)->cqh_first->field.cqe_prev = (elm);              \
        !           259:        (head)->cqh_first = (elm);                                      \
        !           260: }
        !           261: 
        !           262: #define CIRCLEQ_INSERT_TAIL(head, elm, field) {                                \
        !           263:        (elm)->field.cqe_next = (void *)(head);                         \
        !           264:        (elm)->field.cqe_prev = (head)->cqh_last;                       \
        !           265:        if ((head)->cqh_first == (void *)(head))                        \
        !           266:                (head)->cqh_first = (elm);                              \
        !           267:        else                                                            \
        !           268:                (head)->cqh_last->field.cqe_next = (elm);               \
        !           269:        (head)->cqh_last = (elm);                                       \
        !           270: }
        !           271: 
        !           272: #define        CIRCLEQ_REMOVE(head, elm, field) {                              \
        !           273:        if ((elm)->field.cqe_next == (void *)(head))                    \
        !           274:                (head)->cqh_last = (elm)->field.cqe_prev;               \
        !           275:        else                                                            \
        !           276:                (elm)->field.cqe_next->field.cqe_prev =                 \
        !           277:                    (elm)->field.cqe_prev;                              \
        !           278:        if ((elm)->field.cqe_prev == (void *)(head))                    \
        !           279:                (head)->cqh_first = (elm)->field.cqe_next;              \
        !           280:        else                                                            \
        !           281:                (elm)->field.cqe_prev->field.cqe_next =                 \
        !           282:                    (elm)->field.cqe_next;                              \
        !           283: }
        !           284: #endif /* !_SYS_QUEUE_H_ */

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