--- /dev/null
+/*
+ Unix SMB/CIFS implementation.
+ some simple double linked list macros
+
+ Copyright (C) Andrew Tridgell 1998-2010
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/* To use these macros you must have a structure containing a next and
+ prev pointer */
+
+#ifndef _DLINKLIST_H
+#define _DLINKLIST_H
+
+/*
+ February 2010 - changed list format to have a prev pointer from the
+ list head. This makes DLIST_ADD_END() O(1) even though we only have
+ one list pointer.
+
+ The scheme is as follows:
+
+ 1) with no entries in the list:
+ list_head == NULL
+
+ 2) with 1 entry in the list:
+ list_head->next == NULL
+ list_head->prev == list_head
+
+ 3) with 2 entries in the list:
+ list_head->next == element2
+ list_head->prev == element2
+ element2->prev == list_head
+ element2->next == NULL
+
+ 4) with N entries in the list:
+ list_head->next == element2
+ list_head->prev == elementN
+ elementN->prev == element{N-1}
+ elementN->next == NULL
+
+ This allows us to find the tail of the list by using
+ list_head->prev, which means we can add to the end of the list in
+ O(1) time
+
+
+ Note that the 'type' arguments below are no longer needed, but
+ are kept for now to prevent an incompatible argument change
+ */
+
+
+/*
+ add an element at the front of a list
+*/
+#define DLIST_ADD(list, p) \
+do { \
+ if (!(list)) { \
+ (p)->prev = (list) = (p); \
+ (p)->next = NULL; \
+ } else { \
+ (p)->prev = (list)->prev; \
+ (list)->prev = (p); \
+ (p)->next = (list); \
+ (list) = (p); \
+ } \
+} while (0)
+
+/*
+ remove an element from a list
+ Note that the element doesn't have to be in the list. If it
+ isn't then this is a no-op
+*/
+#define DLIST_REMOVE(list, p) \
+do { \
+ if ((p) == (list)) { \
+ if ((p)->next) (p)->next->prev = (p)->prev; \
+ (list) = (p)->next; \
+ } else if ((list) && (p) == (list)->prev) { \
+ (p)->prev->next = NULL; \
+ (list)->prev = (p)->prev; \
+ } else { \
+ if ((p)->prev) (p)->prev->next = (p)->next; \
+ if ((p)->next) (p)->next->prev = (p)->prev; \
+ } \
+ if ((p) != (list)) (p)->next = (p)->prev = NULL; \
+} while (0)
+
+/*
+ find the head of the list given any element in it.
+ Note that this costs O(N), so you should avoid this macro
+ if at all possible!
+*/
+#define DLIST_HEAD(p, result_head) \
+do { \
+ (result_head) = (p); \
+ while (DLIST_PREV(result_head)) (result_head) = (result_head)->prev; \
+} while(0)
+
+/* return the last element in the list */
+#define DLIST_TAIL(list) ((list)?(list)->prev:NULL)
+
+/* return the previous element in the list. */
+#define DLIST_PREV(p) (((p)->prev && (p)->prev->next != NULL)?(p)->prev:NULL)
+
+/* insert 'p' after the given element 'el' in a list. If el is NULL then
+ this is the same as a DLIST_ADD() */
+#define DLIST_ADD_AFTER(list, p, el) \
+do { \
+ if (!(list) || !(el)) { \
+ DLIST_ADD(list, p); \
+ } else { \
+ (p)->prev = (el); \
+ (p)->next = (el)->next; \
+ (el)->next = (p); \
+ if ((p)->next) (p)->next->prev = (p); \
+ if ((list)->prev == (el)) (list)->prev = (p); \
+ }\
+} while (0)
+
+
+/*
+ add to the end of a list.
+ Note that 'type' is ignored
+*/
+#define DLIST_ADD_END(list, p, type) \
+do { \
+ if (!(list)) { \
+ DLIST_ADD(list, p); \
+ } else { \
+ DLIST_ADD_AFTER(list, p, (list)->prev); \
+ } \
+} while (0)
+
+/* promote an element to the from of a list */
+#define DLIST_PROMOTE(list, p) \
+do { \
+ DLIST_REMOVE(list, p); \
+ DLIST_ADD(list, p); \
+} while (0)
+
+/*
+ demote an element to the end of a list.
+ Note that 'type' is ignored
+*/
+#define DLIST_DEMOTE(list, p, type) \
+do { \
+ DLIST_REMOVE(list, p); \
+ DLIST_ADD_END(list, p, NULL); \
+} while (0)
+
+/*
+ concatenate two lists - putting all elements of the 2nd list at the
+ end of the first list.
+ Note that 'type' is ignored
+*/
+#define DLIST_CONCATENATE(list1, list2, type) \
+do { \
+ if (!(list1)) { \
+ (list1) = (list2); \
+ } else { \
+ (list1)->prev->next = (list2); \
+ if (list2) { \
+ void *_tmplist = (void *)(list1)->prev; \
+ (list1)->prev = (list2)->prev; \
+ (list2)->prev = _tmplist; \
+ } \
+ } \
+} while (0)
+
+#endif /* _DLINKLIST_H */
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