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 /* 30 * Embedded Linked Lists 31 * 32 * Simple doubly-linked list implementation. This implementation assumes that 33 * each list element contains an embedded cmd_list_t (previous and next 34 * pointers), which is typically the first member of the element struct. 35 * An additional cmd_list_t is used to store the head (l_next) and tail 36 * (l_prev) pointers. The current head and tail list elements have their 37 * previous and next pointers set to NULL, respectively. 38 */ 39 40 #include <cmd_list.h> 41 #include <cmd.h> 42 43 void 44 cmd_list_append(cmd_list_t *lp, void *new) 45 { 46 cmd_list_t *p = lp->l_prev; /* p = tail list element */ 47 cmd_list_t *q = new; /* q = new list element */ 48 49 lp->l_prev = q; 50 q->l_prev = p; 51 q->l_next = NULL; 52 53 if (p != NULL) 54 p->l_next = q; 55 else 56 lp->l_next = q; 57 } 58 59 void 60 cmd_list_prepend(cmd_list_t *lp, void *new) 61 { 62 cmd_list_t *p = new; /* p = new list element */ 63 cmd_list_t *q = lp->l_next; /* q = head list element */ 64 65 lp->l_next = p; 66 p->l_prev = NULL; 67 p->l_next = q; 68 69 if (q != NULL) 70 q->l_prev = p; 71 else 72 lp->l_prev = p; 73 } 74 75 void 76 cmd_list_insert_before(cmd_list_t *lp, void *before_me, void *new) 77 { 78 cmd_list_t *p = before_me; 79 cmd_list_t *q = new; 80 81 if (p == NULL || p->l_prev == NULL) { 82 cmd_list_prepend(lp, new); 83 return; 84 } 85 86 q->l_prev = p->l_prev; 87 q->l_next = p; 88 p->l_prev = q; 89 q->l_prev->l_next = q; 90 } 91 92 void 93 cmd_list_insert_after(cmd_list_t *lp, void *after_me, void *new) 94 { 95 cmd_list_t *p = after_me; 96 cmd_list_t *q = new; 97 98 if (p == NULL || p->l_next == NULL) { 99 cmd_list_append(lp, new); 100 return; 101 } 102 103 q->l_next = p->l_next; 104 q->l_prev = p; 105 p->l_next = q; 106 q->l_next->l_prev = q; 107 } 108 109 void 110 cmd_list_delete(cmd_list_t *lp, void *existing) 111 { 112 cmd_list_t *p = existing; 113 114 if (p->l_prev != NULL) 115 p->l_prev->l_next = p->l_next; 116 else 117 lp->l_next = p->l_next; 118 119 if (p->l_next != NULL) 120 p->l_next->l_prev = p->l_prev; 121 else 122 lp->l_prev = p->l_prev; 123 } 124