usr/src/lib/libdtrace/common/dt_list.c

   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, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 /*
  30  * Simple doubly-linked list implementation.  This implementation assumes that
  31  * each list element contains an embedded dt_list_t (previous and next
  32  * pointers), which is typically the first member of the element struct.
  33  * An additional dt_list_t is used to store the head (dl_next) and tail
  34  * (dl_prev) pointers.  The current head and tail list elements have their
  35  * previous and next pointers set to NULL, respectively.
  36  */
  37
  38 #include <unistd.h>
  39 #include <assert.h>
  40 #include <dt_list.h>
  41
  42 void
  43 dt_list_append(dt_list_t *dlp, void *new)
  44 {
  45         dt_list_t *p = dlp->dl_prev;    /* p = tail list element */
  46         dt_list_t *q = new;             /* q = new list element */
  47
  48         dlp->dl_prev = q;
  49         q->dl_prev = p;
  50         q->dl_next = NULL;
  51
  52         if (p != NULL) {
  53                 assert(p->dl_next == NULL);
  54                 p->dl_next = q;
  55         } else {
  56                 assert(dlp->dl_next == NULL);
  57                 dlp->dl_next = q;
  58         }
  59 }
  60
  61 void
  62 dt_list_prepend(dt_list_t *dlp, void *new)
  63 {
  64         dt_list_t *p = new;             /* p = new list element */
  65         dt_list_t *q = dlp->dl_next;    /* q = head list element */
  66
  67         dlp->dl_next = p;
  68         p->dl_prev = NULL;
  69         p->dl_next = q;
  70
  71         if (q != NULL) {
  72                 assert(q->dl_prev == NULL);
  73                 q->dl_prev = p;
  74         } else {
  75                 assert(dlp->dl_prev == NULL);
  76                 dlp->dl_prev = p;
  77         }
  78 }
  79
  80 void
  81 dt_list_insert(dt_list_t *dlp, void *after_me, void *new)
  82 {
  83         dt_list_t *p = after_me;
  84         dt_list_t *q = new;
  85
  86         if (p == NULL || p->dl_next == NULL) {
  87                 dt_list_append(dlp, new);
  88                 return;
  89         }
  90
  91         q->dl_next = p->dl_next;
  92         q->dl_prev = p;
  93         p->dl_next = q;
  94         q->dl_next->dl_prev = q;
  95 }
  96
  97 void
  98 dt_list_delete(dt_list_t *dlp, void *existing)
  99 {
 100         dt_list_t *p = existing;
 101
 102         if (p->dl_prev != NULL)
 103                 p->dl_prev->dl_next = p->dl_next;
 104         else
 105                 dlp->dl_next = p->dl_next;
 106
 107         if (p->dl_next != NULL)
 108                 p->dl_next->dl_prev = p->dl_prev;
 109         else
 110                 dlp->dl_prev = p->dl_prev;
 111 }