osfmk/kern/queue.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_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
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 /*
  31  * @OSF_COPYRIGHT@
  32  */
  33 /*
  34  * HISTORY
  35  *
  36  * Revision 1.1.1.1  1998/09/22 21:05:33  wsanchez
  37  * Import of Mac OS X kernel (~semeria)
  38  *
  39  * Revision 1.1.1.1  1998/03/07 02:25:55  wsanchez
  40  * Import of OSF Mach kernel (~mburg)
  41  *
  42  * Revision 1.1.10.3  1995/03/15  17:21:19  bruel
  43  *      compile only if !__GNUC__.
  44  *      [95/03/09            bruel]
  45  *
  46  * Revision 1.1.10.2  1995/01/06  19:48:05  devrcs
  47  *      mk6 CR668 - 1.3b26 merge
  48  *      * Revision 1.1.3.5  1994/05/06  18:51:43  tmt
  49  *      Merge in DEC Alpha changes to osc1.3b19.
  50  *      Merge Alpha changes into osc1.312b source code.
  51  *      Remove ifdef sun around insque and remque.
  52  *      * End1.3merge
  53  *      [1994/11/04  09:29:15  dwm]
  54  *
  55  * Revision 1.1.10.1  1994/09/23  02:25:00  ezf
  56  *      change marker to not FREE
  57  *      [1994/09/22  21:35:34  ezf]
  58  *
  59  * Revision 1.1.3.3  1993/07/28  17:16:26  bernard
  60  *      CR9523 -- Prototypes.
  61  *      [1993/07/21  17:00:38  bernard]
  62  *
  63  * Revision 1.1.3.2  1993/06/02  23:39:41  jeffc
  64  *      Added to OSF/1 R1.3 from NMK15.0.
  65  *      [1993/06/02  21:13:58  jeffc]
  66  *
  67  * Revision 1.1  1992/09/30  02:09:52  robert
  68  *      Initial revision
  69  *
  70  * $EndLog$
  71  */
  72 /* CMU_HIST */
  73 /*
  74  * Revision 2.4  91/05/14  16:45:45  mrt
  75  *      Correcting copyright
  76  *
  77  * Revision 2.3  91/05/08  12:48:22  dbg
  78  *      Compile queue routines on vax.
  79  *      [91/03/26            dbg]
  80  *
  81  * Revision 2.2  91/02/05  17:28:38  mrt
  82  *      Changed to new Mach copyright
  83  *      [91/02/01  16:16:22  mrt]
  84  *
  85  * Revision 2.1  89/08/03  15:51:47  rwd
  86  * Created.
  87  *
  88  * 17-Mar-87  David Golub (dbg) at Carnegie-Mellon University
  89  *      Created from routines written by David L. Black.
  90  *
  91  */
  92 /* CMU_ENDHIST */
  93 /*
  94  * Mach Operating System
  95  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  96  * All Rights Reserved.
  97  *
  98  * Permission to use, copy, modify and distribute this software and its
  99  * documentation is hereby granted, provided that both the copyright
 100  * notice and this permission notice appear in all copies of the
 101  * software, derivative works or modified versions, and any portions
 102  * thereof, and that both notices appear in supporting documentation.
 103  *
 104  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 105  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 106  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 107  *
 108  * Carnegie Mellon requests users of this software to return to
 109  *
 110  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 111  *  School of Computer Science
 112  *  Carnegie Mellon University
 113  *  Pittsburgh PA 15213-3890
 114  *
 115  * any improvements or extensions that they make and grant Carnegie Mellon
 116  * the rights to redistribute these changes.
 117  */
 118 /*
 119  */
 120
 121 /*
 122  *      Routines to implement queue package.
 123  */
 124
 125 #include <kern/queue.h>
 126
 127 #if     !defined(__GNUC__)
 128
 129 /*
 130  *      Insert element at head of queue.
 131  */
 132 void
 133 enqueue_head(
 134         register queue_t        que,
 135         register queue_entry_t  elt)
 136 {
 137         elt->next = que->next;
 138         elt->prev = que;
 139         elt->next->prev = elt;
 140         que->next = elt;
 141 }
 142
 143 /*
 144  *      Insert element at tail of queue.
 145  */
 146 void
 147 enqueue_tail(
 148         register queue_t        que,
 149         register queue_entry_t  elt)
 150 {
 151         elt->next = que;
 152         elt->prev = que->prev;
 153         elt->prev->next = elt;
 154         que->prev = elt;
 155 }
 156
 157 /*
 158  *      Remove and return element at head of queue.
 159  */
 160 queue_entry_t
 161 dequeue_head(
 162         register queue_t        que)
 163 {
 164         register queue_entry_t  elt;
 165
 166         if (que->next == que)
 167                 return((queue_entry_t)0);
 168
 169         elt = que->next;
 170         elt->next->prev = que;
 171         que->next = elt->next;
 172         return(elt);
 173 }
 174
 175 /*
 176  *      Remove and return element at tail of queue.
 177  */
 178 queue_entry_t
 179 dequeue_tail(
 180         register queue_t        que)
 181 {
 182         register queue_entry_t  elt;
 183
 184         if (que->prev == que)
 185                 return((queue_entry_t)0);
 186
 187         elt = que->prev;
 188         elt->prev->next = que;
 189         que->prev = elt->prev;
 190         return(elt);
 191 }
 192
 193 /*
 194  *      Remove arbitrary element from queue.
 195  *      Does not check whether element is on queue - the world
 196  *      will go haywire if it isn't.
 197  */
 198
 199 /*ARGSUSED*/
 200 void
 201 remqueue(
 202         queue_t                 que,
 203         register queue_entry_t  elt)
 204 {
 205         elt->next->prev = elt->prev;
 206         elt->prev->next = elt->next;
 207 }
 208
 209 /*
 210  *      Routines to directly imitate the VAX hardware queue
 211  *      package.
 212  */
 213 void
 214 insque(
 215         register queue_entry_t  entry,
 216         register queue_entry_t  pred)
 217 {
 218         entry->next = pred->next;
 219         entry->prev = pred;
 220         (pred->next)->prev = entry;
 221         pred->next = entry;
 222 }
 223
 224 int
 225 remque(
 226         register queue_entry_t elt)
 227 {
 228         (elt->next)->prev = elt->prev;
 229         (elt->prev)->next = elt->next;
 230         return((int)elt);
 231 }
 232
 233 #endif