From 82ce342055ec8f7a0235d46f5332014eb3f69216 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@openwrt.org>
Date: Tue, 28 Dec 2010 23:59:06 +0100
Subject: merge an avl list implementation (imported from PacketBB)

---
 avl.c | 760 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 760 insertions(+)
 create mode 100644 avl.c

(limited to 'avl.c')

diff --git a/avl.c b/avl.c
new file mode 100644
index 0000000..bde40b7
--- /dev/null
+++ b/avl.c
@@ -0,0 +1,760 @@
+/*
+ * PacketBB handler library (see RFC 5444)
+ * Copyright (c) 2010 Henning Rogge <hrogge@googlemail.com>
+ * Original OLSRd implementation by Hannes Gredler <hannes@gredler.at>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in
+ *   the documentation and/or other materials provided with the
+ *   distribution.
+ * * Neither the name of olsr.org, olsrd nor the names of its
+ *   contributors may be used to endorse or promote products derived
+ *   from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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.
+ *
+ * Visit http://www.olsr.org/git for more information.
+ *
+ * If you find this software useful feel free to make a donation
+ * to the project. For more information see the website or contact
+ * the copyright holders.
+ */
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <time.h>
+#include <string.h>
+
+#include "avl.h"
+#include "list.h"
+
+#define list_merge(_head, _list) list_merge(_list, _head)
+#define list_is_last(_head, _list) list_is_last(_list, _head)
+#define list_is_first(_head, _list) list_is_first(_list, _head)
+
+/**
+ * internal type save inline function to calculate the maximum of
+ * to integers without macro implementation.
+ *
+ * @param x first parameter of maximum function
+ * @param y second parameter of maximum function
+ * @return largest integer of both parameters
+ */
+static inline int avl_max(int x, int y) {
+  return x > y ? x : y;
+}
+
+/**
+ * internal type save inline function to calculate the minimum of
+ * to integers without macro implementation.
+ *
+ * @param x first parameter of minimum function
+ * @param y second parameter of minimum function
+ * @return smallest integer of both parameters
+ */
+static inline int avl_min(int x, int y) {
+  return x < y ? x : y;
+}
+
+static struct avl_node *
+avl_find_rec(struct avl_node *node, const void *key, avl_tree_comp comp, void *ptr, int *cmp_result);
+static void avl_insert_before(struct avl_tree *tree, struct avl_node *pos_node, struct avl_node *node);
+static void avl_insert_after(struct avl_tree *tree, struct avl_node *pos_node, struct avl_node *node);
+static void post_insert(struct avl_tree *tree, struct avl_node *node);
+static void avl_delete_worker(struct avl_tree *tree, struct avl_node *node);
+static void avl_remove(struct avl_tree *tree, struct avl_node *node);
+
+/**
+ * Initialize a new avl_tree struct
+ * @param tree pointer to avl-tree
+ * @param comp pointer to comparator for the tree
+ * @param allow_dups true if the tree allows multiple
+ *   elements with the same
+ * @param ptr custom parameter for comparator
+ */
+void
+avl_init(struct avl_tree *tree, avl_tree_comp comp, bool allow_dups, void *ptr)
+{
+  list_init_head(&tree->list_head);
+  tree->root = NULL;
+  tree->count = 0;
+  tree->comp = comp;
+  tree->allow_dups = allow_dups;
+  tree->cmp_ptr = ptr;
+}
+
+/**
+ * Internal function to support returning the element from a avl tree query
+ * @param tree pointer to avl tree
+ * @param key pointer to key
+ * @param offset offset of node inside the embedded struct
+ * @param mode mode of lookup operation (less equal, equal or greater equal)
+ * @param pointer to elemen, NULL if no fitting one was found
+ */
+void *
+__avl_find_element(struct avl_tree *tree, const void *key, size_t offset, enum avl_find_mode mode) {
+  void *node = NULL;
+
+  switch (mode) {
+    case AVL_FIND_EQUAL:
+      node = avl_find(tree, key);
+      break;
+    case AVL_FIND_LESSEQUAL:
+      node = avl_find_lessequal(tree, key);
+      break;
+    case AVL_FIND_GREATEREQUAL:
+      node = avl_find_greaterequal(tree, key);
+      break;
+  }
+  return node == NULL ? NULL : (((char *)node) - offset);
+}
+
+/**
+ * Finds a node in an avl-tree with a certain key
+ * @param tree pointer to avl-tree
+ * @param key pointer to key
+ * @return pointer to avl-node with key, NULL if no node with
+ *    this key exists.
+ */
+struct avl_node *
+avl_find(struct avl_tree *tree, const void *key)
+{
+  struct avl_node *node;
+  int diff;
+
+  if (tree->root == NULL)
+    return NULL;
+
+  node = avl_find_rec(tree->root, key, tree->comp, tree->cmp_ptr, &diff);
+
+  return diff == 0 ? node : NULL;
+}
+
+/**
+ * Finds the last node in an avl-tree with a key less or equal
+ * than the specified key
+ * @param tree pointer to avl-tree
+ * @param key pointer to specified key
+ * @return pointer to avl-node, NULL if no node with
+ *    key less or equal specified key exists.
+ */
+struct avl_node *
+avl_find_lessequal(struct avl_tree *tree, const void *key) {
+  struct avl_node *node, *next;
+  int diff;
+
+  if (tree->root == NULL)
+    return NULL;
+
+  node = avl_find_rec(tree->root, key, tree->comp, tree->cmp_ptr, &diff);
+
+  /* go left as long as key<node.key */
+  while (diff < 0) {
+    if (list_is_first(&tree->list_head, &node->list)) {
+      return NULL;
+    }
+
+    node = (struct avl_node *)node->list.prev;
+    diff = (*tree->comp) (key, node->key, tree->cmp_ptr);
+  }
+
+  /* go right as long as key>=next_node.key */
+  next = node;
+  while (diff >= 0) {
+    node = next;
+    if (list_is_last(&tree->list_head, &node->list)) {
+      break;
+    }
+
+    next = (struct avl_node *)node->list.next;
+    diff = (*tree->comp) (key, next->key, tree->cmp_ptr);
+  }
+  return node;
+}
+
+/**
+ * Finds the first node in an avl-tree with a key greater or equal
+ * than the specified key
+ * @param tree pointer to avl-tree
+ * @param key pointer to specified key
+ * @return pointer to avl-node, NULL if no node with
+ *    key greater or equal specified key exists.
+ */
+struct avl_node *
+avl_find_greaterequal(struct avl_tree *tree, const void *key) {
+  struct avl_node *node, *next;
+  int diff;
+
+  if (tree->root == NULL)
+    return NULL;
+
+  node = avl_find_rec(tree->root, key, tree->comp, tree->cmp_ptr, &diff);
+
+  /* go right as long as key>node.key */
+  while (diff > 0) {
+    if (list_is_last(&tree->list_head, &node->list)) {
+      return NULL;
+    }
+
+    node = (struct avl_node *)node->list.next;
+    diff = (*tree->comp) (key, node->key, tree->cmp_ptr);
+  }
+
+  /* go left as long as key<=next_node.key */
+  next = node;
+  while (diff <= 0) {
+    node = next;
+    if (list_is_first(&tree->list_head, &node->list)) {
+      break;
+    }
+
+    next = (struct avl_node *)node->list.prev;
+    diff = (*tree->comp) (key, next->key, tree->cmp_ptr);
+  }
+  return node;
+}
+
+/**
+ * Inserts an avl_node into a tree
+ * @param tree pointer to tree
+ * @param new pointer to node
+ * @return 0 if node was inserted successfully, -1 if it was not inserted
+ *   because of a key collision
+ */
+int
+avl_insert(struct avl_tree *tree, struct avl_node *new)
+{
+  struct avl_node *node, *next, *last;
+  int diff;
+
+  new->parent = NULL;
+
+  new->left = NULL;
+  new->right = NULL;
+
+  new->balance = 0;
+  new->leader = true;
+
+  if (tree->root == NULL) {
+    list_add_head(&tree->list_head, &new->list);
+    tree->root = new;
+    tree->count = 1;
+    return 0;
+  }
+
+  node = avl_find_rec(tree->root, new->key, tree->comp, tree->cmp_ptr, &diff);
+
+  last = node;
+
+  while (!list_is_last(&tree->list_head, &last->list)) {
+    next = list_next_element(last, list);
+    if (next->leader) {
+      break;
+    }
+    last = next;
+  }
+
+  diff = (*tree->comp) (new->key, node->key, tree->cmp_ptr);
+
+  if (diff == 0) {
+    if (!tree->allow_dups)
+      return -1;
+
+    new->leader = 0;
+
+    avl_insert_after(tree, last, new);
+    return 0;
+  }
+
+  if (node->balance == 1) {
+    avl_insert_before(tree, node, new);
+
+    node->balance = 0;
+    new->parent = node;
+    node->left = new;
+    return 0;
+  }
+
+  if (node->balance == -1) {
+    avl_insert_after(tree, last, new);
+
+    node->balance = 0;
+    new->parent = node;
+    node->right = new;
+    return 0;
+  }
+
+  if (diff < 0) {
+    avl_insert_before(tree, node, new);
+
+    node->balance = -1;
+    new->parent = node;
+    node->left = new;
+    post_insert(tree, node);
+    return 0;
+  }
+
+  avl_insert_after(tree, last, new);
+
+  node->balance = 1;
+  new->parent = node;
+  node->right = new;
+  post_insert(tree, node);
+  return 0;
+}
+
+/**
+ * Remove a node from an avl tree
+ * @param tree pointer to tree
+ * @param node pointer to node
+ */
+void
+avl_delete(struct avl_tree *tree, struct avl_node *node)
+{
+  struct avl_node *next;
+  struct avl_node *parent;
+  struct avl_node *left;
+  struct avl_node *right;
+  if (node->leader) {
+    if (tree->allow_dups
+        && !list_is_last(&tree->list_head, &node->list)
+        && !(next = list_next_element(node, list))->leader) {
+      next->leader = true;
+      next->balance = node->balance;
+
+      parent = node->parent;
+      left = node->left;
+      right = node->right;
+
+      next->parent = parent;
+      next->left = left;
+      next->right = right;
+
+      if (parent == NULL)
+        tree->root = next;
+
+      else {
+        if (node == parent->left)
+          parent->left = next;
+
+        else
+          parent->right = next;
+      }
+
+      if (left != NULL)
+        left->parent = next;
+
+      if (right != NULL)
+        right->parent = next;
+    }
+
+    else
+      avl_delete_worker(tree, node);
+  }
+
+  avl_remove(tree, node);
+}
+
+static struct avl_node *
+avl_find_rec(struct avl_node *node, const void *key, avl_tree_comp comp, void *cmp_ptr, int *cmp_result)
+{
+  int diff;
+
+  diff = (*comp) (key, node->key, cmp_ptr);
+  *cmp_result = diff;
+
+  if (diff < 0) {
+    if (node->left != NULL)
+      return avl_find_rec(node->left, key, comp, cmp_ptr, cmp_result);
+
+    return node;
+  }
+
+  if (diff > 0) {
+    if (node->right != NULL)
+      return avl_find_rec(node->right, key, comp, cmp_ptr, cmp_result);
+
+    return node;
+  }
+
+  return node;
+}
+
+static void
+avl_rotate_right(struct avl_tree *tree, struct avl_node *node)
+{
+  struct avl_node *left, *parent;
+
+  left = node->left;
+  parent = node->parent;
+
+  left->parent = parent;
+  node->parent = left;
+
+  if (parent == NULL)
+    tree->root = left;
+
+  else {
+    if (parent->left == node)
+      parent->left = left;
+
+    else
+      parent->right = left;
+  }
+
+  node->left = left->right;
+  left->right = node;
+
+  if (node->left != NULL)
+    node->left->parent = node;
+
+  node->balance += 1 - avl_min(left->balance, 0);
+  left->balance += 1 + avl_max(node->balance, 0);
+}
+
+static void
+avl_rotate_left(struct avl_tree *tree, struct avl_node *node)
+{
+  struct avl_node *right, *parent;
+
+  right = node->right;
+  parent = node->parent;
+
+  right->parent = parent;
+  node->parent = right;
+
+  if (parent == NULL)
+    tree->root = right;
+
+  else {
+    if (parent->left == node)
+      parent->left = right;
+
+    else
+      parent->right = right;
+  }
+
+  node->right = right->left;
+  right->left = node;
+
+  if (node->right != NULL)
+    node->right->parent = node;
+
+  node->balance -= 1 + avl_max(right->balance, 0);
+  right->balance -= 1 - avl_min(node->balance, 0);
+}
+
+static void
+post_insert(struct avl_tree *tree, struct avl_node *node)
+{
+  struct avl_node *parent = node->parent;
+
+  if (parent == NULL)
+    return;
+
+  if (node == parent->left) {
+    parent->balance--;
+
+    if (parent->balance == 0)
+      return;
+
+    if (parent->balance == -1) {
+      post_insert(tree, parent);
+      return;
+    }
+
+    if (node->balance == -1) {
+      avl_rotate_right(tree, parent);
+      return;
+    }
+
+    avl_rotate_left(tree, node);
+    avl_rotate_right(tree, node->parent->parent);
+    return;
+  }
+
+  parent->balance++;
+
+  if (parent->balance == 0)
+    return;
+
+  if (parent->balance == 1) {
+    post_insert(tree, parent);
+    return;
+  }
+
+  if (node->balance == 1) {
+    avl_rotate_left(tree, parent);
+    return;
+  }
+
+  avl_rotate_right(tree, node);
+  avl_rotate_left(tree, node->parent->parent);
+}
+
+static void
+avl_insert_before(struct avl_tree *tree, struct avl_node *pos_node, struct avl_node *node)
+{
+  list_add_before(&pos_node->list, &node->list);
+  tree->count++;
+}
+
+static void
+avl_insert_after(struct avl_tree *tree, struct avl_node *pos_node, struct avl_node *node)
+{
+  list_add_after(&pos_node->list, &node->list);
+  tree->count++;
+}
+
+static void
+avl_remove(struct avl_tree *tree, struct avl_node *node)
+{
+  list_remove(&node->list);
+  tree->count--;
+}
+
+static void
+avl_post_delete(struct avl_tree *tree, struct avl_node *node)
+{
+  struct avl_node *parent;
+
+  if ((parent = node->parent) == NULL)
+    return;
+
+  if (node == parent->left) {
+    parent->balance++;
+
+    if (parent->balance == 0) {
+      avl_post_delete(tree, parent);
+      return;
+    }
+
+    if (parent->balance == 1)
+      return;
+
+    if (parent->right->balance == 0) {
+      avl_rotate_left(tree, parent);
+      return;
+    }
+
+    if (parent->right->balance == 1) {
+      avl_rotate_left(tree, parent);
+      avl_post_delete(tree, parent->parent);
+      return;
+    }
+
+    avl_rotate_right(tree, parent->right);
+    avl_rotate_left(tree, parent);
+    avl_post_delete(tree, parent->parent);
+    return;
+  }
+
+  parent->balance--;
+
+  if (parent->balance == 0) {
+    avl_post_delete(tree, parent);
+    return;
+  }
+
+  if (parent->balance == -1)
+    return;
+
+  if (parent->left->balance == 0) {
+    avl_rotate_right(tree, parent);
+    return;
+  }
+
+  if (parent->left->balance == -1) {
+    avl_rotate_right(tree, parent);
+    avl_post_delete(tree, parent->parent);
+    return;
+  }
+
+  avl_rotate_left(tree, parent->left);
+  avl_rotate_right(tree, parent);
+  avl_post_delete(tree, parent->parent);
+}
+
+static struct avl_node *
+avl_local_min(struct avl_node *node)
+{
+  while (node->left != NULL)
+    node = node->left;
+
+  return node;
+}
+
+#if 0
+static struct avl_node *
+avl_local_max(struct avl_node *node)
+{
+  while (node->right != NULL)
+    node = node->right;
+
+  return node;
+}
+#endif
+
+static void
+avl_delete_worker(struct avl_tree *tree, struct avl_node *node)
+{
+  struct avl_node *parent, *min;
+
+  parent = node->parent;
+
+  if (node->left == NULL && node->right == NULL) {
+    if (parent == NULL) {
+      tree->root = NULL;
+      return;
+    }
+
+    if (parent->left == node) {
+      parent->left = NULL;
+      parent->balance++;
+
+      if (parent->balance == 1)
+        return;
+
+      if (parent->balance == 0) {
+        avl_post_delete(tree, parent);
+        return;
+      }
+
+      if (parent->right->balance == 0) {
+        avl_rotate_left(tree, parent);
+        return;
+      }
+
+      if (parent->right->balance == 1) {
+        avl_rotate_left(tree, parent);
+        avl_post_delete(tree, parent->parent);
+        return;
+      }
+
+      avl_rotate_right(tree, parent->right);
+      avl_rotate_left(tree, parent);
+      avl_post_delete(tree, parent->parent);
+      return;
+    }
+
+    if (parent->right == node) {
+      parent->right = NULL;
+      parent->balance--;
+
+      if (parent->balance == -1)
+        return;
+
+      if (parent->balance == 0) {
+        avl_post_delete(tree, parent);
+        return;
+      }
+
+      if (parent->left->balance == 0) {
+        avl_rotate_right(tree, parent);
+        return;
+      }
+
+      if (parent->left->balance == -1) {
+        avl_rotate_right(tree, parent);
+        avl_post_delete(tree, parent->parent);
+        return;
+      }
+
+      avl_rotate_left(tree, parent->left);
+      avl_rotate_right(tree, parent);
+      avl_post_delete(tree, parent->parent);
+      return;
+    }
+  }
+
+  if (node->left == NULL) {
+    if (parent == NULL) {
+      tree->root = node->right;
+      node->right->parent = NULL;
+      return;
+    }
+
+    node->right->parent = parent;
+
+    if (parent->left == node)
+      parent->left = node->right;
+
+    else
+      parent->right = node->right;
+
+    avl_post_delete(tree, node->right);
+    return;
+  }
+
+  if (node->right == NULL) {
+    if (parent == NULL) {
+      tree->root = node->left;
+      node->left->parent = NULL;
+      return;
+    }
+
+    node->left->parent = parent;
+
+    if (parent->left == node)
+      parent->left = node->left;
+
+    else
+      parent->right = node->left;
+
+    avl_post_delete(tree, node->left);
+    return;
+  }
+
+  min = avl_local_min(node->right);
+  avl_delete_worker(tree, min);
+  parent = node->parent;
+
+  min->balance = node->balance;
+  min->parent = parent;
+  min->left = node->left;
+  min->right = node->right;
+
+  if (min->left != NULL)
+    min->left->parent = min;
+
+  if (min->right != NULL)
+    min->right->parent = min;
+
+  if (parent == NULL) {
+    tree->root = min;
+    return;
+  }
+
+  if (parent->left == node) {
+    parent->left = min;
+    return;
+  }
+
+  parent->right = min;
+}
+
+/*
+ * Local Variables:
+ * c-basic-offset: 2
+ * indent-tabs-mode: nil
+ * End:
+ */
-- 
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