osfmk/kern/queue.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * @OSF_COPYRIGHT@
  27  */
  28 /*
  29  * HISTORY
  30  *
  31  * Revision 1.1.1.1  1998/09/22 21:05:33  wsanchez
  32  * Import of Mac OS X kernel (~semeria)
  33  *
  34  * Revision 1.1.1.1  1998/03/07 02:25:55  wsanchez
  35  * Import of OSF Mach kernel (~mburg)
  36  *
  37  * Revision 1.1.10.3  1995/03/15  17:21:19  bruel
  38  *      compile only if !__GNUC__.
  39  *      [95/03/09            bruel]
  40  *
  41  * Revision 1.1.10.2  1995/01/06  19:48:05  devrcs
  42  *      mk6 CR668 - 1.3b26 merge
  43  *      * Revision 1.1.3.5  1994/05/06  18:51:43  tmt
  44  *      Merge in DEC Alpha changes to osc1.3b19.
  45  *      Merge Alpha changes into osc1.312b source code.
  46  *      Remove ifdef sun around insque and remque.
  47  *      * End1.3merge
  48  *      [1994/11/04  09:29:15  dwm]
  49  *
  50  * Revision 1.1.10.1  1994/09/23  02:25:00  ezf
  51  *      change marker to not FREE
  52  *      [1994/09/22  21:35:34  ezf]
  53  *
  54  * Revision 1.1.3.3  1993/07/28  17:16:26  bernard
  55  *      CR9523 -- Prototypes.
  56  *      [1993/07/21  17:00:38  bernard]
  57  *
  58  * Revision 1.1.3.2  1993/06/02  23:39:41  jeffc
  59  *      Added to OSF/1 R1.3 from NMK15.0.
  60  *      [1993/06/02  21:13:58  jeffc]
  61  *
  62  * Revision 1.1  1992/09/30  02:09:52  robert
  63  *      Initial revision
  64  *
  65  * $EndLog$
  66  */
  67 /* CMU_HIST */
  68 /*
  69  * Revision 2.4  91/05/14  16:45:45  mrt
  70  *      Correcting copyright
  71  *
  72  * Revision 2.3  91/05/08  12:48:22  dbg
  73  *      Compile queue routines on vax.
  74  *      [91/03/26            dbg]
  75  *
  76  * Revision 2.2  91/02/05  17:28:38  mrt
  77  *      Changed to new Mach copyright
  78  *      [91/02/01  16:16:22  mrt]
  79  *
  80  * Revision 2.1  89/08/03  15:51:47  rwd
  81  * Created.
  82  *
  83  * 17-Mar-87  David Golub (dbg) at Carnegie-Mellon University
  84  *      Created from routines written by David L. Black.
  85  *
  86  */
  87 /* CMU_ENDHIST */
  88 /*
  89  * Mach Operating System
  90  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  91  * All Rights Reserved.
  92  *
  93  * Permission to use, copy, modify and distribute this software and its
  94  * documentation is hereby granted, provided that both the copyright
  95  * notice and this permission notice appear in all copies of the
  96  * software, derivative works or modified versions, and any portions
  97  * thereof, and that both notices appear in supporting documentation.
  98  *
  99  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 100  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 101  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 102  *
 103  * Carnegie Mellon requests users of this software to return to
 104  *
 105  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 106  *  School of Computer Science
 107  *  Carnegie Mellon University
 108  *  Pittsburgh PA 15213-3890
 109  *
 110  * any improvements or extensions that they make and grant Carnegie Mellon
 111  * the rights to redistribute these changes.
 112  */
 113 /*
 114  */
 115
 116 /*
 117  *      Routines to implement queue package.
 118  */
 119
 120 #include <kern/queue.h>
 121
 122 #if     !defined(__GNUC__)
 123
 124 /*
 125  *      Insert element at head of queue.
 126  */
 127 void
 128 enqueue_head(
 129         register queue_t        que,
 130         register queue_entry_t  elt)
 131 {
 132         elt->next = que->next;
 133         elt->prev = que;
 134         elt->next->prev = elt;
 135         que->next = elt;
 136 }
 137
 138 /*
 139  *      Insert element at tail of queue.
 140  */
 141 void
 142 enqueue_tail(
 143         register queue_t        que,
 144         register queue_entry_t  elt)
 145 {
 146         elt->next = que;
 147         elt->prev = que->prev;
 148         elt->prev->next = elt;
 149         que->prev = elt;
 150 }
 151
 152 /*
 153  *      Remove and return element at head of queue.
 154  */
 155 queue_entry_t
 156 dequeue_head(
 157         register queue_t        que)
 158 {
 159         register queue_entry_t  elt;
 160
 161         if (que->next == que)
 162                 return((queue_entry_t)0);
 163
 164         elt = que->next;
 165         elt->next->prev = que;
 166         que->next = elt->next;
 167         return(elt);
 168 }
 169
 170 /*
 171  *      Remove and return element at tail of queue.
 172  */
 173 queue_entry_t
 174 dequeue_tail(
 175         register queue_t        que)
 176 {
 177         register queue_entry_t  elt;
 178
 179         if (que->prev == que)
 180                 return((queue_entry_t)0);
 181
 182         elt = que->prev;
 183         elt->prev->next = que;
 184         que->prev = elt->prev;
 185         return(elt);
 186 }
 187
 188 /*
 189  *      Remove arbitrary element from queue.
 190  *      Does not check whether element is on queue - the world
 191  *      will go haywire if it isn't.
 192  */
 193
 194 /*ARGSUSED*/
 195 void
 196 remqueue(
 197         queue_t                 que,
 198         register queue_entry_t  elt)
 199 {
 200         elt->next->prev = elt->prev;
 201         elt->prev->next = elt->next;
 202 }
 203
 204 /*
 205  *      Routines to directly imitate the VAX hardware queue
 206  *      package.
 207  */
 208 void
 209 insque(
 210         register queue_entry_t  entry,
 211         register queue_entry_t  pred)
 212 {
 213         entry->next = pred->next;
 214         entry->prev = pred;
 215         (pred->next)->prev = entry;
 216         pred->next = entry;
 217 }
 218
 219 int
 220 remque(
 221         register queue_entry_t elt)
 222 {
 223         (elt->next)->prev = elt->prev;
 224         (elt->prev)->next = elt->next;
 225         return((int)elt);
 226 }
 227
 228 #endif