osfmk/kern/queue.c

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