1/* 2 * Copyright (c) 2000-2009 Apple 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 * Mach Operating System 33 * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University 34 * All Rights Reserved. 35 * 36 * Permission to use, copy, modify and distribute this software and its 37 * documentation is hereby granted, provided that both the copyright 38 * notice and this permission notice appear in all copies of the 39 * software, derivative works or modified versions, and any portions 40 * thereof, and that both notices appear in supporting documentation. 41 * 42 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 43 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 44 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 45 * 46 * Carnegie Mellon requests users of this software to return to 47 * 48 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 49 * School of Computer Science 50 * Carnegie Mellon University 51 * Pittsburgh PA 15213-3890 52 * 53 * any improvements or extensions that they make and grant Carnegie Mellon 54 * the rights to redistribute these changes. 55 */ 56/* 57 */ 58 59/* 60 * Routines to implement queue package. 61 */ 62 63#include <kern/queue.h> 64 65#if !defined(__GNUC__) 66 67/* 68 * Insert element at head of queue. 69 */ 70void 71enqueue_head( 72 register queue_t que, 73 register queue_entry_t elt) 74{ 75 elt->next = que->next; 76 elt->prev = que; 77 elt->next->prev = elt; 78 que->next = elt; 79} 80 81/* 82 * Insert element at tail of queue. 83 */ 84void 85enqueue_tail( 86 register queue_t que, 87 register queue_entry_t elt) 88{ 89 elt->next = que; 90 elt->prev = que->prev; 91 elt->prev->next = elt; 92 que->prev = elt; 93} 94 95/* 96 * Remove and return element at head of queue. 97 */ 98queue_entry_t 99dequeue_head( 100 register queue_t que) 101{ 102 register queue_entry_t elt; 103 104 if (que->next == que) 105 return((queue_entry_t)0); 106 107 elt = que->next; 108 elt->next->prev = que; 109 que->next = elt->next; 110 return(elt); 111} 112 113/* 114 * Remove and return element at tail of queue. 115 */ 116queue_entry_t 117dequeue_tail( 118 register queue_t que) 119{ 120 register queue_entry_t elt; 121 122 if (que->prev == que) 123 return((queue_entry_t)0); 124 125 elt = que->prev; 126 elt->prev->next = que; 127 que->prev = elt->prev; 128 return(elt); 129} 130 131/* 132 * Remove arbitrary element from queue. 133 * Does not check whether element is on a queue - the world 134 * will go haywire if it isn't. 135 */ 136 137/*ARGSUSED*/ 138void 139remqueue( 140 register queue_entry_t elt) 141{ 142 elt->next->prev = elt->prev; 143 elt->prev->next = elt->next; 144} 145 146/* 147 * Routines to directly imitate the VAX hardware queue 148 * package. 149 */ 150void 151insque( 152 register queue_entry_t entry, 153 register queue_entry_t pred) 154{ 155 entry->next = pred->next; 156 entry->prev = pred; 157 (pred->next)->prev = entry; 158 pred->next = entry; 159} 160 161void 162remque( 163 register queue_entry_t elt) 164{ 165 (elt->next)->prev = elt->prev; 166 (elt->prev)->next = elt->next; 167} 168 169#endif 170