112 lines
2.7 KiB
C
112 lines
2.7 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright 2003 Sun Microsystems, Inc. All rights reserved.
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* Use is subject to license terms.
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*/
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#pragma ident "%Z%%M% %I% %E% SMI"
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/*
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* Simple doubly-linked list implementation. This implementation assumes that
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* each list element contains an embedded dt_list_t (previous and next
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* pointers), which is typically the first member of the element struct.
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* An additional dt_list_t is used to store the head (dl_next) and tail
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* (dl_prev) pointers. The current head and tail list elements have their
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* previous and next pointers set to NULL, respectively.
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*/
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#include <unistd.h>
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#include <assert.h>
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#include <dt_list.h>
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void
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dt_list_append(dt_list_t *dlp, void *new)
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{
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dt_list_t *p = dlp->dl_prev; /* p = tail list element */
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dt_list_t *q = new; /* q = new list element */
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dlp->dl_prev = q;
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q->dl_prev = p;
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q->dl_next = NULL;
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if (p != NULL) {
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assert(p->dl_next == NULL);
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p->dl_next = q;
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} else {
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assert(dlp->dl_next == NULL);
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dlp->dl_next = q;
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}
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}
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void
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dt_list_prepend(dt_list_t *dlp, void *new)
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{
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dt_list_t *p = new; /* p = new list element */
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dt_list_t *q = dlp->dl_next; /* q = head list element */
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dlp->dl_next = p;
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p->dl_prev = NULL;
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p->dl_next = q;
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if (q != NULL) {
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assert(q->dl_prev == NULL);
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q->dl_prev = p;
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} else {
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assert(dlp->dl_prev == NULL);
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dlp->dl_prev = p;
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}
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}
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void
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dt_list_insert(dt_list_t *dlp, void *after_me, void *new)
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{
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dt_list_t *p = after_me;
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dt_list_t *q = new;
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if (p == NULL || p->dl_next == NULL) {
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dt_list_append(dlp, new);
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return;
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}
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q->dl_next = p->dl_next;
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q->dl_prev = p;
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p->dl_next = q;
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q->dl_next->dl_prev = q;
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}
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void
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dt_list_delete(dt_list_t *dlp, void *existing)
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{
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dt_list_t *p = existing;
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if (p->dl_prev != NULL)
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p->dl_prev->dl_next = p->dl_next;
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else
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dlp->dl_next = p->dl_next;
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if (p->dl_next != NULL)
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p->dl_next->dl_prev = p->dl_prev;
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else
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dlp->dl_prev = p->dl_prev;
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}
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