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 /* 28 * Simple doubly-linked list implementation. This implementation assumes that 29 * each list element contains an embedded dt_list_t (previous and next 30 * pointers), which is typically the first member of the element struct. 31 * An additional dt_list_t is used to store the head (dl_next) and tail 32 * (dl_prev) pointers. The current head and tail list elements have their 33 * previous and next pointers set to NULL, respectively. 34 */ 35 36 #include <unistd.h> 37 #include <assert.h> 38 #include <dt_list.h> 39 40 void 41 dt_list_append(dt_list_t *dlp, void *new) 42 { 43 dt_list_t *p = dlp->dl_prev; /* p = tail list element */ 44 dt_list_t *q = new; /* q = new list element */ 45 46 dlp->dl_prev = q; 47 q->dl_prev = p; 48 q->dl_next = NULL; 49 50 if (p != NULL) { 51 assert(p->dl_next == NULL); 52 p->dl_next = q; 53 } else { 54 assert(dlp->dl_next == NULL); 55 dlp->dl_next = q; 56 } 57 } 58 59 void 60 dt_list_prepend(dt_list_t *dlp, void *new) 61 { 62 dt_list_t *p = new; /* p = new list element */ 63 dt_list_t *q = dlp->dl_next; /* q = head list element */ 64 65 dlp->dl_next = p; 66 p->dl_prev = NULL; 67 p->dl_next = q; 68 69 if (q != NULL) { 70 assert(q->dl_prev == NULL); 71 q->dl_prev = p; 72 } else { 73 assert(dlp->dl_prev == NULL); 74 dlp->dl_prev = p; 75 } 76 } 77 78 void 79 dt_list_insert(dt_list_t *dlp, void *after_me, void *new) 80 { 81 dt_list_t *p = after_me; 82 dt_list_t *q = new; 83 84 if (p == NULL || p->dl_next == NULL) { 85 dt_list_append(dlp, new); 86 return; 87 } 88 89 q->dl_next = p->dl_next; 90 q->dl_prev = p; 91 p->dl_next = q; 92 q->dl_next->dl_prev = q; 93 } 94 95 void 96 dt_list_delete(dt_list_t *dlp, void *existing) 97 { 98 dt_list_t *p = existing; 99 100 if (p->dl_prev != NULL) 101 p->dl_prev->dl_next = p->dl_next; 102 else 103 dlp->dl_next = p->dl_next; 104 105 if (p->dl_next != NULL) 106 p->dl_next->dl_prev = p->dl_prev; 107 else 108 dlp->dl_prev = p->dl_prev; 109 } 110