osfmk/kern/queue.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * @OSF_COPYRIGHT@
  30  */
  31 /*
  32  * HISTORY
  33  *
  34  * Revision 1.1.1.1  1998/09/22 21:05:33  wsanchez
  35  * Import of Mac OS X kernel (~semeria)
  36  *
  37  * Revision 1.1.1.1  1998/03/07 02:25:55  wsanchez
  38  * Import of OSF Mach kernel (~mburg)
  39  *
  40  * Revision 1.1.10.3  1995/03/15  17:21:19  bruel
  41  *      compile only if !__GNUC__.
  42  *      [95/03/09            bruel]
  43  *
  44  * Revision 1.1.10.2  1995/01/06  19:48:05  devrcs
  45  *      mk6 CR668 - 1.3b26 merge
  46  *      * Revision 1.1.3.5  1994/05/06  18:51:43  tmt
  47  *      Merge in DEC Alpha changes to osc1.3b19.
  48  *      Merge Alpha changes into osc1.312b source code.
  49  *      Remove ifdef sun around insque and remque.
  50  *      * End1.3merge
  51  *      [1994/11/04  09:29:15  dwm]
  52  *
  53  * Revision 1.1.10.1  1994/09/23  02:25:00  ezf
  54  *      change marker to not FREE
  55  *      [1994/09/22  21:35:34  ezf]
  56  *
  57  * Revision 1.1.3.3  1993/07/28  17:16:26  bernard
  58  *      CR9523 -- Prototypes.
  59  *      [1993/07/21  17:00:38  bernard]
  60  *
  61  * Revision 1.1.3.2  1993/06/02  23:39:41  jeffc
  62  *      Added to OSF/1 R1.3 from NMK15.0.
  63  *      [1993/06/02  21:13:58  jeffc]
  64  *
  65  * Revision 1.1  1992/09/30  02:09:52  robert
  66  *      Initial revision
  67  *
  68  * $EndLog$
  69  */
  70 /* CMU_HIST */
  71 /*
  72  * Revision 2.4  91/05/14  16:45:45  mrt
  73  *      Correcting copyright
  74  *
  75  * Revision 2.3  91/05/08  12:48:22  dbg
  76  *      Compile queue routines on vax.
  77  *      [91/03/26            dbg]
  78  *
  79  * Revision 2.2  91/02/05  17:28:38  mrt
  80  *      Changed to new Mach copyright
  81  *      [91/02/01  16:16:22  mrt]
  82  *
  83  * Revision 2.1  89/08/03  15:51:47  rwd
  84  * Created.
  85  *
  86  * 17-Mar-87  David Golub (dbg) at Carnegie-Mellon University
  87  *      Created from routines written by David L. Black.
  88  *
  89  */
  90 /* CMU_ENDHIST */
  91 /*
  92  * Mach Operating System
  93  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  94  * All Rights Reserved.
  95  *
  96  * Permission to use, copy, modify and distribute this software and its
  97  * documentation is hereby granted, provided that both the copyright
  98  * notice and this permission notice appear in all copies of the
  99  * software, derivative works or modified versions, and any portions
 100  * thereof, and that both notices appear in supporting documentation.
 101  *
 102  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 103  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 104  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 105  *
 106  * Carnegie Mellon requests users of this software to return to
 107  *
 108  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 109  *  School of Computer Science
 110  *  Carnegie Mellon University
 111  *  Pittsburgh PA 15213-3890
 112  *
 113  * any improvements or extensions that they make and grant Carnegie Mellon
 114  * the rights to redistribute these changes.
 115  */
 116 /*
 117  */
 118
 119 /*
 120  *      Routines to implement queue package.
 121  */
 122
 123 #include <kern/queue.h>
 124
 125 #if     !defined(__GNUC__)
 126
 127 /*
 128  *      Insert element at head of queue.
 129  */
 130 void
 131 enqueue_head(
 132         register queue_t        que,
 133         register queue_entry_t  elt)
 134 {
 135         elt->next = que->next;
 136         elt->prev = que;
 137         elt->next->prev = elt;
 138         que->next = elt;
 139 }
 140
 141 /*
 142  *      Insert element at tail of queue.
 143  */
 144 void
 145 enqueue_tail(
 146         register queue_t        que,
 147         register queue_entry_t  elt)
 148 {
 149         elt->next = que;
 150         elt->prev = que->prev;
 151         elt->prev->next = elt;
 152         que->prev = elt;
 153 }
 154
 155 /*
 156  *      Remove and return element at head of queue.
 157  */
 158 queue_entry_t
 159 dequeue_head(
 160         register queue_t        que)
 161 {
 162         register queue_entry_t  elt;
 163
 164         if (que->next == que)
 165                 return((queue_entry_t)0);
 166
 167         elt = que->next;
 168         elt->next->prev = que;
 169         que->next = elt->next;
 170         return(elt);
 171 }
 172
 173 /*
 174  *      Remove and return element at tail of queue.
 175  */
 176 queue_entry_t
 177 dequeue_tail(
 178         register queue_t        que)
 179 {
 180         register queue_entry_t  elt;
 181
 182         if (que->prev == que)
 183                 return((queue_entry_t)0);
 184
 185         elt = que->prev;
 186         elt->prev->next = que;
 187         que->prev = elt->prev;
 188         return(elt);
 189 }
 190
 191 /*
 192  *      Remove arbitrary element from queue.
 193  *      Does not check whether element is on queue - the world
 194  *      will go haywire if it isn't.
 195  */
 196
 197 /*ARGSUSED*/
 198 void
 199 remqueue(
 200         queue_t                 que,
 201         register queue_entry_t  elt)
 202 {
 203         elt->next->prev = elt->prev;
 204         elt->prev->next = elt->next;
 205 }
 206
 207 /*
 208  *      Routines to directly imitate the VAX hardware queue
 209  *      package.
 210  */
 211 void
 212 insque(
 213         register queue_entry_t  entry,
 214         register queue_entry_t  pred)
 215 {
 216         entry->next = pred->next;
 217         entry->prev = pred;
 218         (pred->next)->prev = entry;
 219         pred->next = entry;
 220 }
 221
 222 int
 223 remque(
 224         register queue_entry_t elt)
 225 {
 226         (elt->next)->prev = elt->prev;
 227         (elt->prev)->next = elt->next;
 228         return((int)elt);
 229 }
 230
 231 #endif