/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 1999 by Sun Microsystems, Inc.
 * All rights reserved.
 */

#include <mdb/mdb_list.h>
#include <mdb/mdb_debug.h>
#include <unistd.h>

/*
 * Simple doubly-linked list implementation.  This implementation assumes that
 * each list element contains an embedded mdb_list_t (previous and next
 * pointers), which is typically the first member of the element struct.
 * An additional mdb_list_t is used to store the head (ml_next) and tail
 * (ml_prev) pointers.  The current head and tail list elements have their
 * previous and next pointers set to NULL, respectively.
 */

void
mdb_list_append(mdb_list_t *mlp, void *new)
{
        mdb_list_t *p = mlp->ml_prev;   /* p = tail list element */
        mdb_list_t *q = new;            /* q = new list element */

        mlp->ml_prev = q;
        q->ml_prev = p;
        q->ml_next = NULL;

        if (p != NULL) {
                ASSERT(p->ml_next == NULL);
                p->ml_next = q;
        } else {
                ASSERT(mlp->ml_next == NULL);
                mlp->ml_next = q;
        }
}

void
mdb_list_prepend(mdb_list_t *mlp, void *new)
{
        mdb_list_t *p = new;            /* p = new list element */
        mdb_list_t *q = mlp->ml_next;   /* q = head list element */

        mlp->ml_next = p;
        p->ml_prev = NULL;
        p->ml_next = q;

        if (q != NULL) {
                ASSERT(q->ml_prev == NULL);
                q->ml_prev = p;
        } else {
                ASSERT(mlp->ml_prev == NULL);
                mlp->ml_prev = p;
        }
}

void
mdb_list_insert(mdb_list_t *mlp, void *after_me, void *new)
{
        mdb_list_t *p = after_me;
        mdb_list_t *q = new;

        if (p == NULL || p->ml_next == NULL) {
                mdb_list_append(mlp, new);
                return;
        }

        q->ml_next = p->ml_next;
        q->ml_prev = p;
        p->ml_next = q;
        q->ml_next->ml_prev = q;
}

void
mdb_list_delete(mdb_list_t *mlp, void *existing)
{
        mdb_list_t *p = existing;

        if (p->ml_prev != NULL)
                p->ml_prev->ml_next = p->ml_next;
        else
                mlp->ml_next = p->ml_next;

        if (p->ml_next != NULL)
                p->ml_next->ml_prev = p->ml_prev;
        else
                mlp->ml_prev = p->ml_prev;
}

void
mdb_list_move(mdb_list_t *src, mdb_list_t *dst)
{
        dst->ml_prev = src->ml_prev;
        dst->ml_next = src->ml_next;
        src->ml_prev = NULL;
        src->ml_next = NULL;
}