libdtrace/common/dt_list.c

25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis/*
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * CDDL HEADER START
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis *
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25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis */
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis/*
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Use is subject to license terms.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis */
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis#pragma ident   "%Z%%M% %I% %E% SMI"
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis/*
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * Simple doubly-linked list implementation.  This implementation assumes that
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * each list element contains an embedded dt_list_t (previous and next
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * pointers), which is typically the first member of the element struct.
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * An additional dt_list_t is used to store the head (dl_next) and tail
25c28e83beb90e7c80452a7c818c5e6f73a07dc8Piotr Jasiukajtis * (dl_prev) pointers.  The current head and tail list elements have their
 * previous and next pointers set to NULL, respectively.
 */

#include <unistd.h>
#include <assert.h>
#include <dt_list.h>

void
dt_list_append(dt_list_t *dlp, void *new)
{
    dt_list_t *p = dlp->dl_prev;    /* p = tail list element */
    dt_list_t *q = new;     /* q = new list element */

    dlp->dl_prev = q;
    q->dl_prev = p;
    q->dl_next = NULL;

    if (p != NULL) {
        assert(p->dl_next == NULL);
        p->dl_next = q;
    } else {
        assert(dlp->dl_next == NULL);
        dlp->dl_next = q;
    }
}

void
dt_list_prepend(dt_list_t *dlp, void *new)
{
    dt_list_t *p = new;     /* p = new list element */
    dt_list_t *q = dlp->dl_next;    /* q = head list element */

    dlp->dl_next = p;
    p->dl_prev = NULL;
    p->dl_next = q;

    if (q != NULL) {
        assert(q->dl_prev == NULL);
        q->dl_prev = p;
    } else {
        assert(dlp->dl_prev == NULL);
        dlp->dl_prev = p;
    }
}

void
dt_list_insert(dt_list_t *dlp, void *after_me, void *new)
{
    dt_list_t *p = after_me;
    dt_list_t *q = new;

    if (p == NULL || p->dl_next == NULL) {
        dt_list_append(dlp, new);
        return;
    }

    q->dl_next = p->dl_next;
    q->dl_prev = p;
    p->dl_next = q;
    q->dl_next->dl_prev = q;
}

void
dt_list_delete(dt_list_t *dlp, void *existing)
{
    dt_list_t *p = existing;

    if (p->dl_prev != NULL)
        p->dl_prev->dl_next = p->dl_next;
    else
        dlp->dl_next = p->dl_next;

    if (p->dl_next != NULL)
        p->dl_next->dl_prev = p->dl_prev;
    else
        dlp->dl_prev = p->dl_prev;
}