X-Git-Url: https://www.tinc-vpn.org/git/browse?p=tinc;a=blobdiff_plain;f=lib%2Favl_tree.c;h=3bfdfeeeecaf1f23cd0252facf2692eabc816d13;hp=a07f123f9fb3cf7ee814230fcd13bf84a74d3f7c;hb=e8f08ced76bf1b9a94dd0dc874ad22761ad8900b;hpb=099cc867c1a0831add7f1b4046f22ad6bfa5a1ef

diff --git a/lib/avl_tree.c b/lib/avl_tree.c
index a07f123f..3bfdfeee 100644
--- a/lib/avl_tree.c
+++ b/lib/avl_tree.c
@@ -1,9 +1,9 @@
 /*
     avl_tree.c -- avl_ tree and linked list convenience
     Copyright (C) 1998 Michael H. Buselli
-                  2000,2001 Ivo Timmermans <itimmermans@bigfoot.com>,
-                  2000,2001 Guus Sliepen <guus@sliepen.warande.net>
-                  2000,2001 Wessel Dankers <wsl@nl.linux.org>
+                  2000-2005 Ivo Timmermans,
+                  2000-2006 Guus Sliepen <guus@tinc-vpn.org>
+                  2000-2005 Wessel Dankers <wsl@tinc-vpn.org>
 
     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
@@ -21,22 +21,21 @@
 
     Original AVL tree library by Michael H. Buselli <cosine@cosine.org>.
 
-    Modified 2000-11-28 by Wessel Dankers <wsl@nl.linux.org> to use counts
+    Modified 2000-11-28 by Wessel Dankers <wsl@tinc-vpn.org> to use counts
     instead of depths, to add the ->next and ->prev and to generally obfuscate
     the code. Mail me if you found a bug.
 
     Cleaned up and incorporated some of the ideas from the red-black tree
-    library for inclusion into tinc (http://tinc.nl.linux.org/) by
-    Guus Sliepen <guus@sliepen.warande.net>.
+    library for inclusion into tinc (http://www.tinc-vpn.org/) by
+    Guus Sliepen <guus@tinc-vpn.org>.
 
-    $Id: avl_tree.c,v 1.1.2.7 2001/02/27 16:50:29 guus Exp $
+    $Id$
 */
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <xalloc.h>
+#include "system.h"
 
 #include "avl_tree.h"
+#include "xalloc.h"
 
 #ifdef AVL_COUNT
 #define AVL_NODE_COUNT(n)  ((n) ? (n)->count : 0)
@@ -53,662 +52,690 @@
 #endif
 
 #ifndef AVL_DEPTH
-int lg(unsigned int u)
+static int lg(unsigned int u) __attribute__ ((__const__));
+
+static int lg(unsigned int u)
 {
-  int r = 1;
-  if (!u)
-    return 0;
-  if (u & 0xffff0000)
-  {
-    u >>= 16;
-    r += 16;
-  }
-  if (u & 0x0000ff00)
-  {
-    u >>= 8;
-    r += 8;
-  }
-  if (u & 0x000000f0)
-  {
-    u >>= 4;
-    r += 4;
-  }
-  if (u & 0x0000000c)
-  {
-    u >>= 2;
-    r += 2;
-  }
-  if (u & 0x00000002)
-    r++;
-  return r;
+	int r = 1;
+
+	if(!u)
+		return 0;
+
+	if(u & 0xffff0000) {
+		u >>= 16;
+		r += 16;
+	}
+
+	if(u & 0x0000ff00) {
+		u >>= 8;
+		r += 8;
+	}
+
+	if(u & 0x000000f0) {
+		u >>= 4;
+		r += 4;
+	}
+
+	if(u & 0x0000000c) {
+		u >>= 2;
+		r += 2;
+	}
+
+	if(u & 0x00000002)
+		r++;
+
+	return r;
 }
 #endif
 
 /* Internal helper functions */
 
-int avl_check_balance(avl_node_t *node)
+static int avl_check_balance(const avl_node_t *node)
 {
 #ifdef AVL_DEPTH
-  int d;
-  d = R_AVL_DEPTH(node) - L_AVL_DEPTH(node);
-  return d < -1 ? -1 : d > 1 ? 1 : 0;
+	int d;
+
+	d = R_AVL_DEPTH(node) - L_AVL_DEPTH(node);
+
+	return d < -1 ? -1 : d > 1 ? 1 : 0;
 #else
 /*      int d;
  *      d = lg(AVL_R_COUNT(node)) - lg(AVL_L_COUNT(node));
  *      d = d<-1?-1:d>1?1:0;
  */
-  int pl, r;
+	int pl, r;
+
+	pl = lg(AVL_L_COUNT(node));
+	r = AVL_R_COUNT(node);
 
-  pl = lg(AVL_L_COUNT(node));
-  r = AVL_R_COUNT(node);
+	if(r >> pl + 1)
+		return 1;
 
-  if (r >> pl + 1)
-    return 1;
-  if (pl < 2 || r >> pl - 2)
-    return 0;
-  return -1;
+	if(pl < 2 || r >> pl - 2)
+		return 0;
+
+	return -1;
 #endif
 }
 
-void avl_rebalance(avl_tree_t *tree, avl_node_t *node)
+static void avl_rebalance(avl_tree_t *tree, avl_node_t *node)
 {
-  avl_node_t *child;
-  avl_node_t *gchild;
-  avl_node_t *parent;
-  avl_node_t **superparent;
+	avl_node_t *child;
+	avl_node_t *gchild;
+	avl_node_t *parent;
+	avl_node_t **superparent;
 
-  parent = node;
+	parent = node;
 
-  while (node)
-  {
-    parent = node->parent;
+	while(node) {
+		parent = node->parent;
 
-    superparent = parent ? node == parent->left ? &parent->left : &parent->right : &tree->root;
+		superparent =
+			parent ? node ==
+			parent->left ? &parent->left : &parent->right : &tree->root;
 
-    switch (avl_check_balance(node))
-    {
-    case -1:
-      child = node->left;
+		switch (avl_check_balance(node)) {
+			case -1:
+				child = node->left;
 #ifdef AVL_DEPTH
-      if(L_AVL_DEPTH(child) >= R_AVL_DEPTH(child)) {
+				if(L_AVL_DEPTH(child) >= R_AVL_DEPTH(child)) {
 #else
-      if (AVL_L_COUNT(child) >= AVL_R_COUNT(child))
-      {
+				if(AVL_L_COUNT(child) >= AVL_R_COUNT(child)) {
 #endif
-        node->left = child->right;
-        if (node->left)
-          node->left->parent = node;
-        child->right = node;
-        node->parent = child;
-        *superparent = child;
-        child->parent = parent;
+					node->left = child->right;
+					if(node->left)
+						node->left->parent = node;
+
+					child->right = node;
+					node->parent = child;
+					*superparent = child;
+					child->parent = parent;
 #ifdef AVL_COUNT
-        node->count = AVL_CALC_COUNT(node);
-        child->count = AVL_CALC_COUNT(child);
+					node->count = AVL_CALC_COUNT(node);
+					child->count = AVL_CALC_COUNT(child);
 #endif
 #ifdef AVL_DEPTH
-        node->depth = AVL_CALC_DEPTH(node);
-        child->depth = AVL_CALC_DEPTH(child);
+					node->depth = AVL_CALC_DEPTH(node);
+					child->depth = AVL_CALC_DEPTH(child);
 #endif
-      } else
-      {
-        gchild = child->right;
-        node->left = gchild->right;
-        if (node->left)
-          node->left->parent = node;
-        child->right = gchild->left;
-        if (child->right)
-          child->right->parent = child;
-        gchild->right = node;
-        if (gchild->right)
-          gchild->right->parent = gchild;
-        gchild->left = child;
-        if (gchild->left)
-          gchild->left->parent = gchild;
-        *superparent = gchild;
-        gchild->parent = parent;
+				} else {
+					gchild = child->right;
+					node->left = gchild->right;
+
+					if(node->left)
+						node->left->parent = node;
+					child->right = gchild->left;
+
+					if(child->right)
+						child->right->parent = child;
+					gchild->right = node;
+
+					if(gchild->right)
+						gchild->right->parent = gchild;
+					gchild->left = child;
+
+					if(gchild->left)
+						gchild->left->parent = gchild;
+					*superparent = gchild;
+
+					gchild->parent = parent;
 #ifdef AVL_COUNT
-        node->count = AVL_CALC_COUNT(node);
-        child->count = AVL_CALC_COUNT(child);
-        gchild->count = AVL_CALC_COUNT(gchild);
+					node->count = AVL_CALC_COUNT(node);
+					child->count = AVL_CALC_COUNT(child);
+					gchild->count = AVL_CALC_COUNT(gchild);
 #endif
 #ifdef AVL_DEPTH
-        node->depth = AVL_CALC_DEPTH(node);
-        child->depth = AVL_CALC_DEPTH(child);
-        gchild->depth = AVL_CALC_DEPTH(gchild);
+					node->depth = AVL_CALC_DEPTH(node);
+					child->depth = AVL_CALC_DEPTH(child);
+					gchild->depth = AVL_CALC_DEPTH(gchild);
 #endif
-      }
-      break;
-    case 1:
-      child = node->right;
+				}
+				break;
+
+			case 1:
+				child = node->right;
 #ifdef AVL_DEPTH
-      if(R_AVL_DEPTH(child) >= L_AVL_DEPTH(child)) {
+				if(R_AVL_DEPTH(child) >= L_AVL_DEPTH(child)) {
 #else
-      if (AVL_R_COUNT(child) >= AVL_L_COUNT(child))
-      {
+				if(AVL_R_COUNT(child) >= AVL_L_COUNT(child)) {
 #endif
-        node->right = child->left;
-        if (node->right)
-          node->right->parent = node;
-        child->left = node;
-        node->parent = child;
-        *superparent = child;
-        child->parent = parent;
+					node->right = child->left;
+					if(node->right)
+						node->right->parent = node;
+					child->left = node;
+					node->parent = child;
+					*superparent = child;
+					child->parent = parent;
 #ifdef AVL_COUNT
-        node->count = AVL_CALC_COUNT(node);
-        child->count = AVL_CALC_COUNT(child);
+					node->count = AVL_CALC_COUNT(node);
+					child->count = AVL_CALC_COUNT(child);
 #endif
 #ifdef AVL_DEPTH
-        node->depth = AVL_CALC_DEPTH(node);
-        child->depth = AVL_CALC_DEPTH(child);
+					node->depth = AVL_CALC_DEPTH(node);
+					child->depth = AVL_CALC_DEPTH(child);
 #endif
-      } else
-      {
-        gchild = child->left;
-        node->right = gchild->left;
-        if (node->right)
-          node->right->parent = node;
-        child->left = gchild->right;
-        if (child->left)
-          child->left->parent = child;
-        gchild->left = node;
-        if (gchild->left)
-          gchild->left->parent = gchild;
-        gchild->right = child;
-        if (gchild->right)
-          gchild->right->parent = gchild;
-        *superparent = gchild;
-        gchild->parent = parent;
+				} else {
+					gchild = child->left;
+					node->right = gchild->left;
+
+					if(node->right)
+						node->right->parent = node;
+					child->left = gchild->right;
+
+					if(child->left)
+						child->left->parent = child;
+					gchild->left = node;
+
+					if(gchild->left)
+						gchild->left->parent = gchild;
+					gchild->right = child;
+
+					if(gchild->right)
+						gchild->right->parent = gchild;
+
+					*superparent = gchild;
+					gchild->parent = parent;
 #ifdef AVL_COUNT
-        node->count = AVL_CALC_COUNT(node);
-        child->count = AVL_CALC_COUNT(child);
-        gchild->count = AVL_CALC_COUNT(gchild);
+					node->count = AVL_CALC_COUNT(node);
+					child->count = AVL_CALC_COUNT(child);
+					gchild->count = AVL_CALC_COUNT(gchild);
 #endif
 #ifdef AVL_DEPTH
-        node->depth = AVL_CALC_DEPTH(node);
-        child->depth = AVL_CALC_DEPTH(child);
-        gchild->depth = AVL_CALC_DEPTH(gchild);
+					node->depth = AVL_CALC_DEPTH(node);
+					child->depth = AVL_CALC_DEPTH(child);
+					gchild->depth = AVL_CALC_DEPTH(gchild);
 #endif
-      }
-      break;
-    default:
+				}
+				break;
+
+			default:
 #ifdef AVL_COUNT
-      node->count = AVL_CALC_COUNT(node);
+				node->count = AVL_CALC_COUNT(node);
 #endif
 #ifdef AVL_DEPTH
-      node->depth = AVL_CALC_DEPTH(node);
+				node->depth = AVL_CALC_DEPTH(node);
 #endif
-    }
-    node = parent;
-  }
+		}
+		node = parent;
+	}
 }
 
 /* (De)constructors */
 
 avl_tree_t *avl_alloc_tree(avl_compare_t compare, avl_action_t delete)
 {
-  avl_tree_t *tree;
-  
-  tree = xmalloc_and_zero(sizeof(avl_tree_t));
-  tree->compare = compare;
-  tree->delete = delete;
+	avl_tree_t *tree;
 
-  return tree;
+	tree = xmalloc_and_zero(sizeof(avl_tree_t));
+	tree->compare = compare;
+	tree->delete = delete;
+
+	return tree;
 }
 
 void avl_free_tree(avl_tree_t *tree)
 {
-  free(tree);
+	free(tree);
 }
 
 avl_node_t *avl_alloc_node(void)
 {
-  avl_node_t *node;
-  
-  node = xmalloc_and_zero(sizeof(avl_node_t));
-  
-  return node;
+	return xmalloc_and_zero(sizeof(avl_node_t));
 }
 
 void avl_free_node(avl_tree_t *tree, avl_node_t *node)
 {
-  if(node->data && tree->delete)
-    tree->delete(node->data);
-  free(node);    
+	if(node->data && tree->delete)
+		tree->delete(node->data);
+
+	free(node);
 }
 
 /* Searching */
 
 void *avl_search(const avl_tree_t *tree, const void *data)
 {
-  avl_node_t *node;
-  
-  node = avl_search_node(tree, data);
+	avl_node_t *node;
 
-  return node?node->data:NULL;
+	node = avl_search_node(tree, data);
+
+	return node ? node->data : NULL;
 }
 
 void *avl_search_closest(const avl_tree_t *tree, const void *data, int *result)
 {
-  avl_node_t *node;
-  
-  node = avl_search_closest_node(tree, data, result);
+	avl_node_t *node;
+
+	node = avl_search_closest_node(tree, data, result);
 
-  return node?node->data:NULL;
+	return node ? node->data : NULL;
 }
 
 void *avl_search_closest_smaller(const avl_tree_t *tree, const void *data)
 {
-  avl_node_t *node;
-  
-  node = avl_search_closest_smaller_node(tree, data);
+	avl_node_t *node;
 
-  return node?node->data:NULL;
+	node = avl_search_closest_smaller_node(tree, data);
+
+	return node ? node->data : NULL;
 }
 
 void *avl_search_closest_greater(const avl_tree_t *tree, const void *data)
 {
-  avl_node_t *node;
-  
-  node = avl_search_closest_greater_node(tree, data);
+	avl_node_t *node;
+
+	node = avl_search_closest_greater_node(tree, data);
 
-  return node?node->data:NULL;
+	return node ? node->data : NULL;
 }
 
 avl_node_t *avl_search_node(const avl_tree_t *tree, const void *data)
 {
-  avl_node_t *node;
-  int result;
- 
-  node = avl_search_closest_node(tree, data, &result);
-  
-  return result?NULL:node;
+	avl_node_t *node;
+	int result;
+
+	node = avl_search_closest_node(tree, data, &result);
+
+	return result ? NULL : node;
 }
 
-avl_node_t *avl_search_closest_node(const avl_tree_t *tree, const void *data, int *result)
+avl_node_t *avl_search_closest_node(const avl_tree_t *tree, const void *data,
+									int *result)
 {
-  avl_node_t *node;
-  int c;
-
-  node = tree->root;
-
-  if (!node)
-  {
-    if(result)
-      *result = 0;
-    return NULL;
-  }
-
-  for (;;)
-  {
-    c = tree->compare(data, node->data);
-
-    if (c < 0)
-    {
-      if (node->left)
-        node = node->left;
-      else
-      {
-        if(result)
-          *result = -1;
-        break;
-      }
-    }
-    else if (c > 0)
-    {
-      if (node->right)
-        node = node->right;
-      else
-      {
-        if(result)
-          *result = 1;
-        break;
-      }
-    }
-    else
-    {
-      if(result)
-        *result = 0;
-      break;
-    }
-  }
-
-  return node;
+	avl_node_t *node;
+	int c;
+
+	node = tree->root;
+
+	if(!node) {
+		if(result)
+			*result = 0;
+		return NULL;
+	}
+
+	for(;;) {
+		c = tree->compare(data, node->data);
+
+		if(c < 0) {
+			if(node->left)
+				node = node->left;
+			else {
+				if(result)
+					*result = -1;
+				break;
+			}
+		} else if(c > 0) {
+			if(node->right)
+				node = node->right;
+			else {
+				if(result)
+					*result = 1;
+				break;
+			}
+		} else {
+			if(result)
+				*result = 0;
+			break;
+		}
+	}
+
+	return node;
 }
 
-avl_node_t *avl_search_closest_smaller_node(const avl_tree_t *tree, const void *data)
+avl_node_t *avl_search_closest_smaller_node(const avl_tree_t *tree,
+											const void *data)
 {
-  avl_node_t *node;
-  int result;
-  
-  node = avl_search_closest_node(tree, data, &result);
-  
-  if(result < 0)
-    node = node->prev;
-  
-  return node;
+	avl_node_t *node;
+	int result;
+
+	node = avl_search_closest_node(tree, data, &result);
+
+	if(result < 0)
+		node = node->prev;
+
+	return node;
 }
 
-avl_node_t *avl_search_closest_greater_node(const avl_tree_t *tree, const void *data)
+avl_node_t *avl_search_closest_greater_node(const avl_tree_t *tree,
+											const void *data)
 {
-  avl_node_t *node;
-  int result;
-  
-  node = avl_search_closest_node(tree, data, &result);
-  
-  if(result > 0)
-    node = node->next;
-  
-  return node;
+	avl_node_t *node;
+	int result;
+
+	node = avl_search_closest_node(tree, data, &result);
+
+	if(result > 0)
+		node = node->next;
+
+	return node;
 }
 
 /* Insertion and deletion */
 
 avl_node_t *avl_insert(avl_tree_t *tree, void *data)
 {
-  avl_node_t *closest, *new;
-  int result;
-
-  if (!tree->root)
-  {
-    new = avl_alloc_node();
-    new->data = data;
-    avl_insert_top(tree, new);
-  }
-  else
-  {
-    closest = avl_search_closest_node(tree, data, &result);
-    switch(result)
-    {
-      case -1:
-        new = avl_alloc_node();
-        new->data = data;
-        avl_insert_before(tree, closest, new);
-        break;
-      case 1:
-        new = avl_alloc_node();
-        new->data = data;
-        avl_insert_after(tree, closest, new);
-        break;
-      default:
-        return NULL;
-    }
-  }
-  
+	avl_node_t *closest, *new;
+	int result;
+
+	if(!tree->root) {
+		new = avl_alloc_node();
+		new->data = data;
+		avl_insert_top(tree, new);
+	} else {
+		closest = avl_search_closest_node(tree, data, &result);
+
+		switch (result) {
+			case -1:
+				new = avl_alloc_node();
+				new->data = data;
+				avl_insert_before(tree, closest, new);
+				break;
+
+			case 1:
+				new = avl_alloc_node();
+				new->data = data;
+				avl_insert_after(tree, closest, new);
+				break;
+
+			default:
+				return NULL;
+		}
+	}
+
 #ifdef AVL_COUNT
-  new->count = 1;
+	new->count = 1;
 #endif
 #ifdef AVL_DEPTH
-  new->depth = 1;
+	new->depth = 1;
 #endif
 
-  return new;
+	return new;
 }
 
 avl_node_t *avl_insert_node(avl_tree_t *tree, avl_node_t *node)
 {
-  avl_node_t *closest;
-  int result;
-
-  if (!tree->root)
-    avl_insert_top(tree, node);
-  else
-  {
-    closest = avl_search_closest_node(tree, node->data, &result);
-    switch(result)
-    {
-      case -1:
-        avl_insert_before(tree, closest, node);
-        break;
-      case 1:
-        avl_insert_after(tree, closest, node);
-        break;
-      case 0:
-        return NULL;
-    }
-  }
-  
+	avl_node_t *closest;
+	int result;
+
+	if(!tree->root)
+		avl_insert_top(tree, node);
+	else {
+		closest = avl_search_closest_node(tree, node->data, &result);
+
+		switch (result) {
+			case -1:
+				avl_insert_before(tree, closest, node);
+				break;
+
+			case 1:
+				avl_insert_after(tree, closest, node);
+				break;
+
+			case 0:
+				return NULL;
+		}
+	}
+
 #ifdef AVL_COUNT
-  node->count = 1;
+	node->count = 1;
 #endif
 #ifdef AVL_DEPTH
-  node->depth = 1;
+	node->depth = 1;
 #endif
 
-  return node;
+	return node;
 }
 
 void avl_insert_top(avl_tree_t *tree, avl_node_t *node)
 {
-  node->prev = node->next = node->parent = NULL;
-  tree->head = tree->tail = tree->root = node;
+	node->prev = node->next = node->parent = NULL;
+	tree->head = tree->tail = tree->root = node;
 }
 
-void avl_insert_before(avl_tree_t *tree, avl_node_t *before, avl_node_t *node)
+void avl_insert_before(avl_tree_t *tree, avl_node_t *before,
+					   avl_node_t *node)
 {
-  if (!before)
-    return tree->tail ? avl_insert_after(tree, tree->tail, node) : avl_insert_top(tree, node);
-
-  node->next = before;
-  node->parent = before;
-  node->prev = before->prev;
-
-  if(before->left)
-    return avl_insert_after(tree, before->prev, node);
-
-  if (before->prev)
-    before->prev->next = node;
-  else
-    tree->head = node;
-
-  before->prev = node;
-  before->left = node;
-
-  avl_rebalance(tree, before->parent);
+	if(!before) {
+		if(tree->tail)
+			avl_insert_after(tree, tree->tail, node);
+		else
+			avl_insert_top(tree, node);
+		return;
+	}
+
+	node->next = before;
+	node->parent = before;
+	node->prev = before->prev;
+
+	if(before->left) {
+		avl_insert_after(tree, before->prev, node);
+		return;
+	}
+
+	if(before->prev)
+		before->prev->next = node;
+	else
+		tree->head = node;
+
+	before->prev = node;
+	before->left = node;
+
+	avl_rebalance(tree, before);
 }
 
 void avl_insert_after(avl_tree_t *tree, avl_node_t *after, avl_node_t *node)
 {
-  if (!after)
-    return tree->head ? avl_insert_before(tree, tree->head, node) : avl_insert_top(tree, node);
-
-  if(after->right)
-    return avl_insert_before(tree, after->next, node);
-
-  node->prev = after;
-  node->parent = after;
-  node->next = after->next;
-
-  if (after->next)
-    after->next->prev = node;
-  else
-    tree->tail = node;
-    
-  after->next = node;
-  after->right = node;
-
-  avl_rebalance(tree, after->parent);
+	if(!after) {
+		if(tree->head)
+			avl_insert_before(tree, tree->head, node);
+		else
+			avl_insert_top(tree, node);
+		return;
+	}
+
+	if(after->right) {
+		avl_insert_before(tree, after->next, node);
+		return;
+	}
+
+	node->prev = after;
+	node->parent = after;
+	node->next = after->next;
+
+	if(after->next)
+		after->next->prev = node;
+	else
+		tree->tail = node;
+
+	after->next = node;
+	after->right = node;
+
+	avl_rebalance(tree, after);
 }
 
 avl_node_t *avl_unlink(avl_tree_t *tree, void *data)
 {
-  avl_node_t *node;
-  
-  node = avl_search_node(tree, data);
+	avl_node_t *node;
 
-  if(node)
-    avl_unlink_node(tree, node);
+	node = avl_search_node(tree, data);
 
-  return node;
+	if(node)
+		avl_unlink_node(tree, node);
+
+	return node;
 }
 
 void avl_unlink_node(avl_tree_t *tree, avl_node_t *node)
 {
-  avl_node_t *parent;
-  avl_node_t **superparent;
-  avl_node_t *subst, *left, *right;
-  avl_node_t *balnode;
-
-  if (node->prev)
-    node->prev->next = node->next;
-  else
-    tree->head = node->next;
-  if (node->next)
-    node->next->prev = node->prev;
-  else
-    tree->tail = node->prev;
-
-  parent = node->parent;
-
-  superparent = parent ? node == parent->left ? &parent->left : &parent->right : &tree->root;
-
-  left = node->left;
-  right = node->right;
-  if (!left)
-  {
-    *superparent = right;
-    if (right)
-      right->parent = parent;
-    balnode = parent;
-  } else if (!right)
-  {
-    *superparent = left;
-    left->parent = parent;
-    balnode = parent;
-  } else
-  {
-    subst = node->prev;
-    if (subst == left)
-    {
-      balnode = subst;
-    } else
-    {
-      balnode = subst->parent;
-      balnode->right = subst->left;
-      if (balnode->right)
-        balnode->right->parent = balnode;
-      subst->left = left;
-      left->parent = subst;
-    }
-    subst->right = right;
-    subst->parent = parent;
-    right->parent = subst;
-    *superparent = subst;
-  }
-
-  avl_rebalance(tree, balnode);
+	avl_node_t *parent;
+	avl_node_t **superparent;
+	avl_node_t *subst, *left, *right;
+	avl_node_t *balnode;
+
+	if(node->prev)
+		node->prev->next = node->next;
+	else
+		tree->head = node->next;
+	if(node->next)
+		node->next->prev = node->prev;
+	else
+		tree->tail = node->prev;
+
+	parent = node->parent;
+
+	superparent =
+		parent ? node ==
+		parent->left ? &parent->left : &parent->right : &tree->root;
+
+	left = node->left;
+	right = node->right;
+	if(!left) {
+		*superparent = right;
+
+		if(right)
+			right->parent = parent;
+
+		balnode = parent;
+	} else if(!right) {
+		*superparent = left;
+		left->parent = parent;
+		balnode = parent;
+	} else {
+		subst = node->prev;
+
+		if(subst == left) {
+			balnode = subst;
+		} else {
+			balnode = subst->parent;
+			balnode->right = subst->left;
+
+			if(balnode->right)
+				balnode->right->parent = balnode;
+
+			subst->left = left;
+			left->parent = subst;
+		}
+
+		subst->right = right;
+		subst->parent = parent;
+		right->parent = subst;
+		*superparent = subst;
+	}
+
+	avl_rebalance(tree, balnode);
+
+	node->next = node->prev = node->parent = node->left = node->right = NULL;
+
+#ifdef AVL_COUNT
+	node->count = 0;
+#endif
+#ifdef AVL_DEPTH
+	node->depth = 0;
+#endif
 }
 
 void avl_delete_node(avl_tree_t *tree, avl_node_t *node)
 {
-  avl_unlink_node(tree, node);
-  avl_free_node(tree, node);
+	avl_unlink_node(tree, node);
+	avl_free_node(tree, node);
 }
 
 void avl_delete(avl_tree_t *tree, void *data)
 {
-  avl_node_t *node;
+	avl_node_t *node;
 
-  node = avl_search_node(tree, data);
+	node = avl_search_node(tree, data);
 
-  if (node)
-    avl_delete_node(tree, node);
+	if(node)
+		avl_delete_node(tree, node);
 }
 
 /* Fast tree cleanup */
 
 void avl_delete_tree(avl_tree_t *tree)
 {
-  avl_node_t *node, *next;
-  
-  for(node = tree->root; node; node = next)
-  {
-    next = node->next;
-    avl_free_node(tree, node);
-  }
-  
-  avl_free_tree(tree);
+	avl_node_t *node, *next;
+
+	for(node = tree->head; node; node = next) {
+		next = node->next;
+		avl_free_node(tree, node);
+	}
+
+	avl_free_tree(tree);
 }
 
 /* Tree walking */
 
-void avl_foreach(avl_tree_t *tree, avl_action_t action)
+void avl_foreach(const avl_tree_t *tree, avl_action_t action)
 {
-  avl_node_t *node, *next;
-  
-  for(node = tree->head; node; node = next)
-    {
-      next = node->next;
-      action(node->data);
-    }
+	avl_node_t *node, *next;
+
+	for(node = tree->head; node; node = next) {
+		next = node->next;
+		action(node->data);
+	}
 }
 
-void avl_foreach_node(avl_tree_t *tree, avl_action_t action)
+void avl_foreach_node(const avl_tree_t *tree, avl_action_t action)
 {
-  avl_node_t *node, *next;
-  
-  for(node = tree->head; node; node = next)
-    {
-      next = node->next;
-      action(node);
-    }
+	avl_node_t *node, *next;
+
+	for(node = tree->head; node; node = next) {
+		next = node->next;
+		action(node);
+	}
 }
 
 /* Indexing */
 
 #ifdef AVL_COUNT
-unsigned int avl_count(avl_tree_t *tree)
+unsigned int avl_count(const avl_tree_t *tree)
 {
-  return AVL_NODE_COUNT(tree->root);
+	return AVL_NODE_COUNT(tree->root);
 }
 
 avl_node_t *avl_get_node(const avl_tree_t *tree, unsigned int index)
 {
-  avl_node_t *node;
-  unsigned int c;
-
-  node = tree->root;
-
-  while (node)
-  {
-    c = AVL_L_COUNT(node);
-
-    if (index < c)
-    {
-      node = node->left;
-    } else if (index > c)
-    {
-      node = node->right;
-      index -= c + 1;
-    } else
-    {
-      return node;
-    }
-  }
-  
-  return NULL;
+	avl_node_t *node;
+	unsigned int c;
+
+	node = tree->root;
+
+	while(node) {
+		c = AVL_L_COUNT(node);
+
+		if(index < c) {
+			node = node->left;
+		} else if(index > c) {
+			node = node->right;
+			index -= c + 1;
+		} else {
+			return node;
+		}
+	}
+
+	return NULL;
 }
 
 unsigned int avl_index(const avl_node_t *node)
 {
-  avl_node_t *next;
-  unsigned int index;
+	avl_node_t *next;
+	unsigned int index;
 
-  index = AVL_L_COUNT(node);
+	index = AVL_L_COUNT(node);
 
-  while ((next = node->parent))
-  {
-    if (node == next->right)
-      index += AVL_L_COUNT(next) + 1;
-    node = next;
-  }
+	while((next = node->parent)) {
+		if(node == next->right)
+			index += AVL_L_COUNT(next) + 1;
+		node = next;
+	}
 
-  return index;
+	return index;
 }
 #endif
 #ifdef AVL_DEPTH
-unsigned int avl_depth(avl_tree_t *tree)
+unsigned int avl_depth(const avl_tree_t *tree)
 {
-  return AVL_NODE_DEPTH(tree->root);
+	return AVL_NODE_DEPTH(tree->root);
 }
 #endif