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      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 (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 /*
     22  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
     23  * Use is subject to license terms.
     24  */
     25 
     26 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     27 
     28 /*
     29  * Embedded Linked Lists
     30  *
     31  * Simple doubly-linked list implementation.  This implementation assumes that
     32  * each list element contains an embedded ipmi_list_t (previous and next
     33  * pointers), which is typically the first member of the element struct.
     34  * An additional ipmi_list_t is used to store the head (l_next) and tail
     35  * (l_prev) pointers.  The current head and tail list elements have their
     36  * previous and next pointers set to NULL, respectively.
     37  */
     38 
     39 #include <assert.h>
     40 #include <ipmi_impl.h>
     41 
     42 void
     43 ipmi_list_append(ipmi_list_t *lp, void *new)
     44 {
     45 	ipmi_list_t *p = lp->l_prev;	/* p = tail list element */
     46 	ipmi_list_t *q = new;		/* q = new list element */
     47 
     48 	lp->l_prev = q;
     49 	q->l_prev = p;
     50 	q->l_next = NULL;
     51 
     52 	if (p != NULL) {
     53 		assert(p->l_next == NULL);
     54 		p->l_next = q;
     55 	} else {
     56 		assert(lp->l_next == NULL);
     57 		lp->l_next = q;
     58 	}
     59 }
     60 
     61 void
     62 ipmi_list_prepend(ipmi_list_t *lp, void *new)
     63 {
     64 	ipmi_list_t *p = new;		/* p = new list element */
     65 	ipmi_list_t *q = lp->l_next;	/* q = head list element */
     66 
     67 	lp->l_next = p;
     68 	p->l_prev = NULL;
     69 	p->l_next = q;
     70 
     71 	if (q != NULL) {
     72 		assert(q->l_prev == NULL);
     73 		q->l_prev = p;
     74 	} else {
     75 		assert(lp->l_prev == NULL);
     76 		lp->l_prev = p;
     77 	}
     78 }
     79 
     80 void
     81 ipmi_list_insert_before(ipmi_list_t *lp, void *before_me, void *new)
     82 {
     83 	ipmi_list_t *p = before_me;
     84 	ipmi_list_t *q = new;
     85 
     86 	if (p == NULL || p->l_prev == NULL) {
     87 		ipmi_list_prepend(lp, new);
     88 		return;
     89 	}
     90 
     91 	q->l_prev = p->l_prev;
     92 	q->l_next = p;
     93 	p->l_prev = q;
     94 	q->l_prev->l_next = q;
     95 }
     96 
     97 void
     98 ipmi_list_insert_after(ipmi_list_t *lp, void *after_me, void *new)
     99 {
    100 	ipmi_list_t *p = after_me;
    101 	ipmi_list_t *q = new;
    102 
    103 	if (p == NULL || p->l_next == NULL) {
    104 		ipmi_list_append(lp, new);
    105 		return;
    106 	}
    107 
    108 	q->l_next = p->l_next;
    109 	q->l_prev = p;
    110 	p->l_next = q;
    111 	q->l_next->l_prev = q;
    112 }
    113 
    114 void
    115 ipmi_list_delete(ipmi_list_t *lp, void *existing)
    116 {
    117 	ipmi_list_t *p = existing;
    118 
    119 	if (p->l_prev != NULL)
    120 		p->l_prev->l_next = p->l_next;
    121 	else
    122 		lp->l_next = p->l_next;
    123 
    124 	if (p->l_next != NULL)
    125 		p->l_next->l_prev = p->l_prev;
    126 	else
    127 		lp->l_prev = p->l_prev;
    128 }
    129