/*
* Search for the node which contains "value". The algorithm is a
* simple binary tree search.
*
* return value:
* NULL: the value is not in the AVL tree
* *where (if not NULL) is set to indicate the insertion point
* "void *" of the found tree node
*/
void *
avl_find(avl_tree_t *tree, void *value, avl_index_t *where)
{
avl_node_t *node;
avl_node_t *prev = NULL;
int child = 0;
int diff;
size_t off = tree->avl_offset;
for (node = tree->avl_root; node != NULL;
node = node->avl_child[child]) {
prev = node;
diff = tree->avl_compar(value, AVL_NODE2DATA(node, off));
if (!((-1 <= diff) && (diff <= 1))) {
filebench_log(LOG_ERROR, "avl compare error");
return (NULL);
}
if (diff == 0) {
if (where != NULL)
*where = 0;
return (AVL_NODE2DATA(node, off));
}
child = avl_balance2child[1 + diff];
}
if (where != NULL)
*where = AVL_MKINDEX(prev, child);
return (NULL);
}
/*
* Search for the node which contains "value". The algorithm is a
* simple binary tree search.
*
* return value:
* NULL: the value is not in the AVL tree
* *where (if not NULL) is set to indicate the insertion point
* "void *" of the found tree node
*/
void *
avl_find(avl_tree_t *tree, const void *value, avl_index_t *where)
{
avl_node_t *node;
avl_node_t *prev = NULL;
int child = 0;
int diff;
size_t off = tree->avl_offset;
for (node = tree->avl_root; node != NULL;
node = node->avl_child[child]) {
prev = node;
diff = tree->avl_compar(value, AVL_NODE2DATA(node, off));
//ASSERT(-1 <= diff && diff <= 1);
if (diff == 0) {
#ifdef DEBUG
if (where != NULL)
*where = 0;
#endif
return (AVL_NODE2DATA(node, off));
}
child = avl_balance2child[1 + diff];
}
if (where != NULL)
*where = AVL_MKINDEX(prev, child);
return (NULL);
}
/*
* Insert "new_data" in "tree" in the given "direction" either after or
* before (AVL_AFTER, AVL_BEFORE) the data "here".
*
* Insertions can only be done at empty leaf points in the tree, therefore
* if the given child of the node is already present we move to either
* the AVL_PREV or AVL_NEXT and reverse the insertion direction. Since
* every other node in the tree is a leaf, this always works.
*
* To help developers using this interface, we assert that the new node
* is correctly ordered at every step of the way in DEBUG kernels.
*/
void
avl_insert_here(
avl_tree_t *tree,
void *new_data,
void *here,
int direction)
{
avl_node_t *node;
int child = direction; /* rely on AVL_BEFORE == 0, AVL_AFTER == 1 */
#ifdef DEBUG
int diff;
#endif
//ASSERT(tree != NULL);
//ASSERT(new_data != NULL);
//ASSERT(here != NULL);
//ASSERT(direction == AVL_BEFORE || direction == AVL_AFTER);
/*
* If corresponding child of node is not NULL, go to the neighboring
* node and reverse the insertion direction.
*/
node = AVL_DATA2NODE(here, tree->avl_offset);
#ifdef DEBUG
diff = tree->avl_compar(new_data, here);
//ASSERT(-1 <= diff && diff <= 1);
//ASSERT(diff != 0);
//ASSERT(diff > 0 ? child == 1 : child == 0);
#endif
if (node->avl_child[child] != NULL) {
node = node->avl_child[child];
child = 1 - child;
while (node->avl_child[child] != NULL) {
#ifdef DEBUG
diff = tree->avl_compar(new_data,
AVL_NODE2DATA(node, tree->avl_offset));
//ASSERT(-1 <= diff && diff <= 1);
//ASSERT(diff != 0);
//ASSERT(diff > 0 ? child == 1 : child == 0);
#endif
node = node->avl_child[child];
}
#ifdef DEBUG
diff = tree->avl_compar(new_data,
AVL_NODE2DATA(node, tree->avl_offset));
//ASSERT(-1 <= diff && diff <= 1);
//ASSERT(diff != 0);
//ASSERT(diff > 0 ? child == 1 : child == 0);
#endif
}
//ASSERT(node->avl_child[child] == NULL);
avl_insert(tree, new_data, AVL_MKINDEX(node, child));
}
/*
* Return the highest valued node in a tree or NULL.
* (rightmost child from root of tree)
*/
void *
avl_last(avl_tree_t *tree)
{
avl_node_t *node;
avl_node_t *prev = NULL;
size_t off = tree->avl_offset;
for (node = tree->avl_root; node != NULL; node = node->avl_child[1])
prev = node;
if (prev != NULL)
return (AVL_NODE2DATA(prev, off));
return (NULL);
}
/*
* Return the lowest valued node in a tree or NULL.
* (leftmost child from root of tree)
*/
void *
avl_first(avl_tree_t *tree)
{
avl_node_t *node;
avl_node_t *prev = NULL;
unsigned int off = tree->avl_offset;
for (node = tree->avl_root; node != NULL; node = node->avl_child[0])
prev = node;
if (prev != NULL)
return (AVL_NODE2DATA(prev, off));
return (NULL);
}
/*
* Access the node immediately before or after an insertion point.
*
* "avl_index_t" is a (avl_node_t *) with the bottom bit indicating a child
*
* Return value:
* NULL: no node in the given direction
* "void *" of the found tree node
*/
void *
avl_nearest(avl_tree_t *tree, avl_index_t where, int direction)
{
int child = AVL_INDEX2CHILD(where);
avl_node_t *node = AVL_INDEX2NODE(where);
void *data;
size_t off = tree->avl_offset;
if (node == NULL) {
return (NULL);
}
data = AVL_NODE2DATA(node, off);
if (child != direction)
return (data);
return (avl_walk(tree, data, direction));
}
/*
* Walk from one node to the previous valued node (ie. an infix walk
* towards the left). At any given node we do one of 2 things:
*
* - If there is a left child, go to it, then to it's rightmost descendant.
*
* - otherwise we return thru parent nodes until we've come from a right child.
*
* Return Value:
* NULL - if at the end of the nodes
* otherwise next node
*/
void *
avl_walk(avl_tree_t *tree, void *oldnode, int left)
{
size_t off = tree->avl_offset;
avl_node_t *node = AVL_DATA2NODE(oldnode, off);
int right = 1 - left;
int was_child;
/*
* nowhere to walk to if tree is empty
*/
if (node == NULL)
return (NULL);
/*
* Visit the previous valued node. There are two possibilities:
*
* If this node has a left child, go down one left, then all
* the way right.
*/
if (node->avl_child[left] != NULL) {
for (node = node->avl_child[left];
node->avl_child[right] != NULL;
node = node->avl_child[right])
;
/*
* Otherwise, return thru left children as far as we can.
*/
} else {
for (;;) {
was_child = AVL_XCHILD(node);
node = AVL_XPARENT(node);
if (node == NULL)
return (NULL);
if (was_child == right)
break;
}
}
return (AVL_NODE2DATA(node, off));
}
/*
* Access the node immediately before or after an insertion point.
*
* "avl_index_t" is a (avl_node_t *) with the bottom bit indicating a child
*
* Return value:
* NULL: no node in the given direction
* "void *" of the found tree node
*/
void *
avl_nearest(avl_tree_t *tree, avl_index_t where, int direction)
{
int child = AVL_INDEX2CHILD(where);
avl_node_t *node = AVL_INDEX2NODE(where);
void *data;
size_t off = tree->avl_offset;
if (node == NULL) {
if (tree->avl_root != NULL)
filebench_log(LOG_ERROR,
"Null Node Pointer Supplied");
return (NULL);
}
data = AVL_NODE2DATA(node, off);
if (child != direction)
return (data);
return (avl_walk(tree, data, direction));
}
