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+/*
+ * Copyright 1990 William Pugh
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * Permission to include in quagga provide on March 31, 2016
+ */
+
+/*
+ * Skip List implementation based on code from William Pugh.
+ * ftp://ftp.cs.umd.edu/pub/skipLists/
+ */
+
+/* skiplist.h */
+
+
+#ifndef _ZEBRA_SKIPLIST_H
+#define _ZEBRA_SKIPLIST_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define SKIPLIST_0TIMER_DEBUG 1
+
+/*
+ * skiplistnodes must always contain data to be valid. Adding an
+ * empty node to a list is invalid
+ */
+struct skiplistnode {
+ void *key;
+ void *value;
+#if SKIPLIST_0TIMER_DEBUG
+ int flags;
+#define SKIPLIST_NODE_FLAG_INSERTED 0x00000001
+#endif
+
+ struct skiplistnode *forward[1]; /* variable sized */
+};
+
+struct skiplist {
+ int flags;
+
+#define SKIPLIST_FLAG_ALLOW_DUPLICATES 0x00000001
+
+ int level; /* max lvl (1 + current # of levels in list) */
+ unsigned int count;
+ struct skiplistnode *header;
+ int *level_stats;
+ struct skiplistnode
+ *last; /* last real list item (NULL if empty list) */
+
+ /*
+ * Returns -1 if val1 < val2, 0 if equal?, 1 if val1 > val2.
+ * Used as definition of sorted for listnode_add_sort
+ */
+ int (*cmp)(const void *val1, const void *val2);
+
+ /* callback to free user-owned data when listnode is deleted. supplying
+ * this callback is very much encouraged!
+ */
+ void (*del)(void *val);
+};
+
+
+/* Prototypes. */
+extern struct skiplist *
+skiplist_new(/* encouraged: set list.del callback on new lists */
+ int flags,
+ int (*cmp)(const void *key1,
+ const void *key2), /* NULL => default cmp */
+ void (*del)(void *val)); /* NULL => no auto val free */
+
+extern void skiplist_free(struct skiplist *);
+
+extern int skiplist_insert(register struct skiplist *l, register void *key,
+ register void *value);
+
+extern int skiplist_delete(register struct skiplist *l, register void *key,
+ register void *value);
+
+extern int skiplist_search(register struct skiplist *l, register void *key,
+ void **valuePointer);
+
+extern int skiplist_first_value(register struct skiplist *l, /* in */
+ register const void *key, /* in */
+ void **valuePointer, /* in/out */
+ void **cursor); /* out */
+
+extern int skiplist_next_value(register struct skiplist *l, /* in */
+ register const void *key, /* in */
+ void **valuePointer, /* in/out */
+ void **cursor); /* in/out */
+
+extern int skiplist_first(register struct skiplist *l, void **keyPointer,
+ void **valuePointer);
+
+extern int skiplist_last(register struct skiplist *l, void **keyPointer,
+ void **valuePointer);
+
+extern int skiplist_delete_first(register struct skiplist *l);
+
+extern int skiplist_next(register struct skiplist *l, /* in */
+ void **keyPointer, /* out */
+ void **valuePointer, /* out */
+ void **cursor); /* in/out */
+
+extern int skiplist_empty(register struct skiplist *l); /* in */
+
+extern unsigned int skiplist_count(register struct skiplist *l); /* in */
+
+struct vty;
+extern void skiplist_debug(struct vty *vty, struct skiplist *l);
+
+extern void skiplist_test(struct vty *vty);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _ZEBRA_SKIPLIST_H */