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Annotation of Net2/vm/queue.h, revision 1.1

1.1     ! root        1: /* 
        !             2:  * Copyright (c) 1991 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * This code is derived from software contributed to Berkeley by
        !             6:  * The Mach Operating System project at Carnegie-Mellon University.
        !             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     7.3 (Berkeley) 4/21/91
        !            37:  *
        !            38:  *
        !            39:  * Copyright (c) 1987, 1990 Carnegie-Mellon University.
        !            40:  * All rights reserved.
        !            41:  *
        !            42:  * Author: Avadis Tevanian, Jr.
        !            43:  * 
        !            44:  * Permission to use, copy, modify and distribute this software and
        !            45:  * its documentation is hereby granted, provided that both the copyright
        !            46:  * notice and this permission notice appear in all copies of the
        !            47:  * software, derivative works or modified versions, and any portions
        !            48:  * thereof, and that both notices appear in supporting documentation.
        !            49:  * 
        !            50:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 
        !            51:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 
        !            52:  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            53:  * 
        !            54:  * Carnegie Mellon requests users of this software to return to
        !            55:  *
        !            56:  *  Software Distribution Coordinator  or  [email protected]
        !            57:  *  School of Computer Science
        !            58:  *  Carnegie Mellon University
        !            59:  *  Pittsburgh PA 15213-3890
        !            60:  *
        !            61:  * any improvements or extensions that they make and grant Carnegie the
        !            62:  * rights to redistribute these changes.
        !            63:  */
        !            64: 
        !            65: /*
        !            66:  *     Type definitions for generic queues.
        !            67:  */
        !            68: 
        !            69: #ifndef        _QUEUE_H_
        !            70: #define        _QUEUE_H_
        !            71: 
        !            72: struct queue_entry {
        !            73:        struct queue_entry      *next;          /* next element */
        !            74:        struct queue_entry      *prev;          /* previous element */
        !            75: };
        !            76: 
        !            77: typedef struct queue_entry     *queue_t;
        !            78: typedef        struct queue_entry      queue_head_t;
        !            79: typedef        struct queue_entry      queue_chain_t;
        !            80: typedef        struct queue_entry      *queue_entry_t;
        !            81: 
        !            82: #define round_queue(size)      (((size)+7) & (~7))
        !            83: 
        !            84: #define enqueue(queue,elt)     enqueue_tail(queue, elt)
        !            85: #define        dequeue(queue)          dequeue_head(queue)
        !            86: 
        !            87: #define        enqueue_head(queue,elt) insque(elt,queue)
        !            88: #define        enqueue_tail(queue,elt) insque(elt,(queue)->prev)
        !            89: #define        remqueue(queue,elt)     remque(elt)
        !            90: 
        !            91: #define        queue_init(q)           ((q)->next = (q)->prev = q)
        !            92: #define        queue_first(q)          ((q)->next)
        !            93: #define        queue_next(qc)          ((qc)->next)
        !            94: #define        queue_end(q, qe)        ((q) == (qe))
        !            95: #define        queue_empty(q)          queue_end((q), queue_first(q))
        !            96: 
        !            97: #define queue_enter(head, elt, type, field) {                  \
        !            98:        if (queue_empty((head))) {                              \
        !            99:                (head)->next = (queue_entry_t) elt;             \
        !           100:                (head)->prev = (queue_entry_t) elt;             \
        !           101:                (elt)->field.next = head;                       \
        !           102:                (elt)->field.prev = head;                       \
        !           103:        } else {                                                \
        !           104:                register queue_entry_t prev = (head)->prev;     \
        !           105:                (elt)->field.prev = prev;                       \
        !           106:                (elt)->field.next = head;                       \
        !           107:                (head)->prev = (queue_entry_t)(elt);            \
        !           108:                ((type)prev)->field.next = (queue_entry_t)(elt);\
        !           109:        }                                                       \
        !           110: }
        !           111: 
        !           112: #define        queue_field(head, thing, type, field)                   \
        !           113:                (((head) == (thing)) ? (head) : &((type)(thing))->field)
        !           114: 
        !           115: #define        queue_remove(head, elt, type, field) {                  \
        !           116:        register queue_entry_t next = (elt)->field.next;        \
        !           117:        register queue_entry_t prev = (elt)->field.prev;        \
        !           118:        queue_field((head), next, type, field)->prev = prev;    \
        !           119:        queue_field((head), prev, type, field)->next = next;    \
        !           120: }
        !           121: 
        !           122: #define        queue_assign(to, from, type, field) {                   \
        !           123:        ((type)((from)->prev))->field.next = (to);              \
        !           124:        ((type)((from)->next))->field.prev = (to);              \
        !           125:        *to = *from;                                            \
        !           126: }
        !           127: 
        !           128: #define        queue_remove_first(h, e, t, f) {                        \
        !           129:        e = (t) queue_first((h));                               \
        !           130:        queue_remove((h), (e), t, f);                           \
        !           131: }
        !           132: 
        !           133: #endif /* !_QUEUE_H_ */

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