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
cmd_list_append(cmd_list_t * lp,void * new)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
cmd_list_prepend(cmd_list_t * lp,void * new)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
cmd_list_insert_before(cmd_list_t * lp,void * before_me,void * new)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
cmd_list_insert_after(cmd_list_t * lp,void * after_me,void * new)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
cmd_list_delete(cmd_list_t * lp,void * existing)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