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 2003 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 /* 30 * Simple doubly-linked list implementation. This implementation assumes that 31 * each list element contains an embedded dt_list_t (previous and next 32 * pointers), which is typically the first member of the element struct. 33 * An additional dt_list_t is used to store the head (dl_next) and tail 34 * (dl_prev) pointers. The current head and tail list elements have their 35 * previous and next pointers set to NULL, respectively. 36 */ 37 38 #include <unistd.h> 39 #include <assert.h> 40 #include <dt_list.h> 41 42 void 43 dt_list_append(dt_list_t *dlp, void *new) 44 { 45 dt_list_t *p = dlp->dl_prev; /* p = tail list element */ 46 dt_list_t *q = new; /* q = new list element */ 47 48 dlp->dl_prev = q; 49 q->dl_prev = p; 50 q->dl_next = NULL; 51 52 if (p != NULL) { 53 assert(p->dl_next == NULL); 54 p->dl_next = q; 55 } else { 56 assert(dlp->dl_next == NULL); 57 dlp->dl_next = q; 58 } 59 } 60 61 void 62 dt_list_prepend(dt_list_t *dlp, void *new) 63 { 64 dt_list_t *p = new; /* p = new list element */ 65 dt_list_t *q = dlp->dl_next; /* q = head list element */ 66 67 dlp->dl_next = p; 68 p->dl_prev = NULL; 69 p->dl_next = q; 70 71 if (q != NULL) { 72 assert(q->dl_prev == NULL); 73 q->dl_prev = p; 74 } else { 75 assert(dlp->dl_prev == NULL); 76 dlp->dl_prev = p; 77 } 78 } 79 80 void 81 dt_list_insert(dt_list_t *dlp, void *after_me, void *new) 82 { 83 dt_list_t *p = after_me; 84 dt_list_t *q = new; 85 86 if (p == NULL || p->dl_next == NULL) { 87 dt_list_append(dlp, new); 88 return; 89 } 90 91 q->dl_next = p->dl_next; 92 q->dl_prev = p; 93 p->dl_next = q; 94 q->dl_next->dl_prev = q; 95 } 96 97 void 98 dt_list_delete(dt_list_t *dlp, void *existing) 99 { 100 dt_list_t *p = existing; 101 102 if (p->dl_prev != NULL) 103 p->dl_prev->dl_next = p->dl_next; 104 else 105 dlp->dl_next = p->dl_next; 106 107 if (p->dl_next != NULL) 108 p->dl_next->dl_prev = p->dl_prev; 109 else 110 dlp->dl_prev = p->dl_prev; 111 } 112