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/*
* Oracle Linux DTrace.
* Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
/*
* Simple doubly-linked list implementation. This implementation assumes that
* each list element contains an embedded dt_list_t (previous and next
* pointers), which is typically the first member of the element struct.
* An additional dt_list_t is used to store the head (dl_next) and tail
* (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;
}
size_t
dt_list_length(dt_list_t *dlp)
{
dt_list_t *p;
size_t len = 0;
for (p = dt_list_next(dlp); p != NULL; p = dt_list_next(p))
len++;
return len;
}
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