Annotation of Net2/vm/queue.h, revision 1.1.1.1

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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