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-rw-r--r--libbanshee/libcompat/radix-tree.c364
1 files changed, 364 insertions, 0 deletions
diff --git a/libbanshee/libcompat/radix-tree.c b/libbanshee/libcompat/radix-tree.c
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index 00000000000..18f8929ad2d
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+++ b/libbanshee/libcompat/radix-tree.c
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+/*
+ * Modified to work in GCC in 2003 by Daniel Berlin
+ * Copyright (C) 2001 Momchil Velikov
+ * Portions Copyright (C) 2001 Christoph Hellwig
+ *
+ * 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 2, 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, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include "radix-tree.h"
+#define ARRAY_SIZE(a) (sizeof (a) / sizeof ((a)[0]))
+/*
+ * Radix tree node definition.
+ */
+#define RADIX_TREE_MAP_SHIFT 6
+#define RADIX_TREE_MAP_SIZE (1UL << RADIX_TREE_MAP_SHIFT)
+#define RADIX_TREE_MAP_MASK (RADIX_TREE_MAP_SIZE-1)
+
+struct radix_tree_node {
+ unsigned int count;
+ void *slots[RADIX_TREE_MAP_SIZE];
+};
+
+struct radix_tree_path {
+ struct radix_tree_node *node, **slot;
+};
+
+#define RADIX_TREE_INDEX_BITS (8 /* CHAR_BIT */ * sizeof(unsigned long))
+#define RADIX_TREE_MAX_PATH (RADIX_TREE_INDEX_BITS/RADIX_TREE_MAP_SHIFT + 2)
+
+static unsigned long height_to_maxindex[RADIX_TREE_MAX_PATH];
+
+
+/*
+ * This assumes that the caller has performed appropriate preallocation, and
+ * that the caller has pinned this thread of control to the current CPU.
+ */
+static struct radix_tree_node *
+radix_tree_node_alloc(struct radix_tree_root *root)
+{
+ struct radix_tree_node *ret;
+
+ ret = (struct radix_tree_node *)
+ calloc (1, sizeof (struct radix_tree_node));
+ if (!ret)
+ abort ();
+ return ret;
+}
+
+static inline void
+radix_tree_node_free(struct radix_tree_node *node)
+{
+ free (node);
+}
+
+
+/*
+ * Return the maximum key which can be store into a
+ * radix tree with height HEIGHT.
+ */
+static inline unsigned long radix_tree_maxindex(unsigned int height)
+{
+ return height_to_maxindex[height];
+}
+
+/*
+ * Extend a radix tree so it can store key @index.
+ */
+static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
+{
+ struct radix_tree_node *node;
+ unsigned int height;
+
+ /* Figure out what the height should be. */
+ height = root->height + 1;
+ while (index > radix_tree_maxindex(height))
+ height++;
+
+ if (root->rnode) {
+ do {
+ if (!(node = radix_tree_node_alloc(root)))
+ return -ENOMEM;
+
+ /* Increase the height. */
+ node->slots[0] = root->rnode;
+ node->count = 1;
+ root->rnode = node;
+ root->height++;
+ } while (height > root->height);
+ } else
+ root->height = height;
+
+ return 0;
+}
+
+/**
+ * radix_tree_insert - insert into a radix tree
+ * @root: radix tree root
+ * @index: index key
+ * @item: item to insert
+ *
+ * Insert an item into the radix tree at position @index.
+ */
+int radix_tree_insert(struct radix_tree_root *root, unsigned long index,
+ void *item)
+{
+ struct radix_tree_node *node = NULL, *tmp, **slot;
+ unsigned int height, shift;
+ int error;
+
+ /* Make sure the tree is high enough. */
+ if (index > radix_tree_maxindex(root->height)) {
+ error = radix_tree_extend(root, index);
+ if (error)
+ return error;
+ }
+
+ slot = &root->rnode;
+ height = root->height;
+ shift = (height-1) * RADIX_TREE_MAP_SHIFT;
+
+ while (height > 0) {
+ if (*slot == NULL) {
+ /* Have to add a child node. */
+ if (!(tmp = radix_tree_node_alloc(root)))
+ return -ENOMEM;
+ *slot = tmp;
+ if (node)
+ node->count++;
+ }
+
+ /* Go a level down. */
+ node = *slot;
+ slot = (struct radix_tree_node **)
+ (node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK));
+ shift -= RADIX_TREE_MAP_SHIFT;
+ height--;
+ }
+
+ if (*slot != NULL)
+ return -EEXIST;
+ if (node)
+ node->count++;
+
+ *slot = item;
+ return 0;
+}
+
+/**
+ * radix_tree_lookup - perform lookup operation on a radix tree
+ * @root: radix tree root
+ * @index: index key
+ *
+ * Lookup them item at the position @index in the radix tree @root.
+ */
+void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
+{
+ unsigned int height, shift;
+ struct radix_tree_node **slot;
+
+ height = root->height;
+ if (index > radix_tree_maxindex(height))
+ return NULL;
+
+ shift = (height-1) * RADIX_TREE_MAP_SHIFT;
+ slot = &root->rnode;
+
+ while (height > 0) {
+ if (*slot == NULL)
+ return NULL;
+
+ slot = (struct radix_tree_node **)
+ ((*slot)->slots + ((index >> shift) & RADIX_TREE_MAP_MASK));
+ shift -= RADIX_TREE_MAP_SHIFT;
+ height--;
+ }
+
+ return (void *) *slot;
+}
+
+static /* inline */ unsigned int
+__lookup(struct radix_tree_root *root, void **results, unsigned long index,
+ unsigned int max_items, unsigned long *next_index)
+{
+ unsigned int nr_found = 0;
+ unsigned int shift;
+ unsigned int height = root->height;
+ struct radix_tree_node *slot;
+
+ shift = (height-1) * RADIX_TREE_MAP_SHIFT;
+ slot = root->rnode;
+
+ while (height > 0) {
+ unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
+
+ for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
+ if (slot->slots[i] != NULL)
+ break;
+ index &= ~((1 << shift) - 1);
+ index += 1 << shift;
+ if (index == 0)
+ goto out; /* 32-bit wraparound */
+ }
+ if (i == RADIX_TREE_MAP_SIZE)
+ goto out;
+ height--;
+ if (height == 0) { /* Bottom level: grab some items */
+ unsigned long j = index & RADIX_TREE_MAP_MASK;
+
+ for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
+ index++;
+ if (slot->slots[j]) {
+ results[nr_found++] = slot->slots[j];
+ if (nr_found == max_items)
+ goto out;
+ }
+ }
+ }
+ shift -= RADIX_TREE_MAP_SHIFT;
+ slot = slot->slots[i];
+ }
+ out:
+ *next_index = index;
+ return nr_found;
+}
+
+/**
+ * radix_tree_gang_lookup - perform multiple lookup on a radix tree
+ * @root: radix tree root
+ * @results: where the results of the lookup are placed
+ * @first_index: start the lookup from this key
+ * @max_items: place up to this many items at *results
+ *
+ * Performs an index-ascending scan of the tree for present items. Places
+ * them at *@results and returns the number of items which were placed at
+ * *@results.
+ *
+ * The implementation is naive.
+ */
+unsigned int
+radix_tree_gang_lookup(struct radix_tree_root *root, void **results,
+ unsigned long first_index, unsigned int max_items)
+{
+ const unsigned long max_index = radix_tree_maxindex(root->height);
+ unsigned long cur_index = first_index;
+ unsigned int ret = 0;
+
+ if (root->rnode == NULL)
+ goto out;
+ if (max_index == 0) { /* Bah. Special case */
+ if (first_index == 0) {
+ if (max_items > 0) {
+ *results = root->rnode;
+ ret = 1;
+ }
+ }
+ goto out;
+ }
+ while (ret < max_items) {
+ unsigned int nr_found;
+ unsigned long next_index; /* Index of next search */
+
+ if (cur_index > max_index)
+ break;
+ nr_found = __lookup(root, results + ret, cur_index,
+ max_items - ret, &next_index);
+ ret += nr_found;
+ if (next_index == 0)
+ break;
+ cur_index = next_index;
+ }
+ out:
+ return ret;
+}
+
+/**
+ * radix_tree_delete - delete an item from a radix tree
+ * @root: radix tree root
+ * @index: index key
+ *
+ * Remove the item at @index from the radix tree rooted at @root.
+ *
+ * Returns the address of the deleted item, or NULL if it was not present.
+ */
+void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
+{
+ struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
+ unsigned int height, shift;
+ void *ret = NULL;
+
+ height = root->height;
+ if (index > radix_tree_maxindex(height))
+ goto out;
+
+ shift = (height-1) * RADIX_TREE_MAP_SHIFT;
+ pathp->node = NULL;
+ pathp->slot = &root->rnode;
+
+ while (height > 0) {
+ if (*pathp->slot == NULL)
+ goto out;
+
+ pathp[1].node = *pathp[0].slot;
+ pathp[1].slot = (struct radix_tree_node **)
+ (pathp[1].node->slots + ((index >> shift) & RADIX_TREE_MAP_MASK));
+ pathp++;
+ shift -= RADIX_TREE_MAP_SHIFT;
+ height--;
+ }
+
+ ret = *pathp[0].slot;
+ if (ret == NULL)
+ goto out;
+
+ *pathp[0].slot = NULL;
+ while (pathp[0].node && --pathp[0].node->count == 0) {
+ pathp--;
+ *pathp[0].slot = NULL;
+ radix_tree_node_free(pathp[1].node);
+ }
+
+ if (root->rnode == NULL)
+ root->height = 0; /* Empty tree, we can reset the height */
+ out:
+ return ret;
+}
+
+
+static unsigned long __maxindex(unsigned int height)
+{
+ unsigned int tmp = height * RADIX_TREE_MAP_SHIFT;
+ unsigned long index = (~0UL >> (RADIX_TREE_INDEX_BITS - tmp - 1)) >> 1;
+
+ if (tmp >= RADIX_TREE_INDEX_BITS)
+ index = ~0UL;
+ return index;
+}
+
+static void radix_tree_init_maxindex(void)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(height_to_maxindex); i++)
+ height_to_maxindex[i] = __maxindex(i);
+}
+
+void radix_tree_init(void)
+{
+ radix_tree_init_maxindex();
+}
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