1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 /* Copyright (c) 1988 AT&T */ 30 /* All Rights Reserved */ 31 32 33 /* 34 * insque() and remque() insert or remove an element from a queue. 35 * The queue is built from a doubly linked list whose elements are 36 * defined by a structure where the first member of the structure 37 * points to the next element in the queue and the second member 38 * of the structure points to the previous element in the queue. 39 */ 40 41 #pragma weak insque = _insque 42 #pragma weak remque = _remque 43 44 #include "synonyms.h" 45 #include <sys/types.h> 46 #include <stdlib.h> 47 #include <search.h> 48 49 void 50 insque(void *elem, void *pred) 51 { 52 if (pred == NULL) { /* This is the first element being inserted. */ 53 ((struct qelem *)elem)->q_forw = NULL; 54 ((struct qelem *)elem)->q_back = NULL; 55 } else if (((struct qelem *)pred)->q_forw == NULL) { 56 /* The element is inserted at */ 57 /* the end of the queue. */ 58 ((struct qelem *)elem)->q_forw = NULL; 59 ((struct qelem *)elem)->q_back = pred; 60 ((struct qelem *)pred)->q_forw = elem; 61 } else { /* The element is inserted in the middle of */ 62 /* the queue. */ 63 ((struct qelem *)elem)->q_forw = ((struct qelem *)pred)->q_forw; 64 ((struct qelem *)elem)->q_back = pred; 65 ((struct qelem *)pred)->q_forw->q_back = elem; 66 ((struct qelem *)pred)->q_forw = elem; 67 } 68 } 69 70 void 71 remque(void *elem) 72 { 73 if (((struct qelem *)elem)->q_back == NULL) { 74 /* The first element is removed. */ 75 if (((struct qelem *)elem)->q_forw == NULL) 76 /* The only element is removed. */ 77 return; 78 ((struct qelem *)elem)->q_forw->q_back = NULL; 79 } else if (((struct qelem *)elem)->q_forw == NULL) { 80 /* The last element is removed */ 81 ((struct qelem *)elem)->q_back->q_forw = NULL; 82 } else { /* The middle element is removed. */ 83 ((struct qelem *)elem)->q_back->q_forw = 84 ((struct qelem *)elem)->q_forw; 85 ((struct qelem *)elem)->q_forw->q_back = 86 ((struct qelem *)elem)->q_back; 87 } 88 } 89