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authormatt <matt@NetBSD.org>2001-10-24 22:40:56 +0000
committermatt <matt@NetBSD.org>2001-10-24 22:40:56 +0000
commit920cfb5205211cbf8a86e17bc75e0ab63795f9ba (patch)
tree05e46b2f353f60713ae46233836379d9bca1b830 /sys/lib
parentc642c12a279c12fe3bff37142509e9995903431d (diff)
Add "Red Black +" balanced binary tree routines to libkern. These provide
O(log(N)) insertation, deletion, and lookup times. However, unlike most red-black implemenations, this one does no additional memory allocations.
Diffstat (limited to 'sys/lib')
-rw-r--r--sys/lib/libkern/rb.c370
-rw-r--r--sys/lib/libkern/rb.h80
2 files changed, 450 insertions, 0 deletions
diff --git a/sys/lib/libkern/rb.c b/sys/lib/libkern/rb.c
new file mode 100644
index 00000000000..232d3a2cd38
--- /dev/null
+++ b/sys/lib/libkern/rb.c
@@ -0,0 +1,370 @@
+/*-
+ * Copyright (c) 2001 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Matt Thomas <matt@3am-software.com>.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the NetBSD
+ * Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ */
+
+#include <sys/types.h>
+#include <stddef.h>
+#ifndef _KERNEL
+#include <assert.h>
+#define KASSERT(s) assert(s)
+#endif
+#include "rb.h"
+
+static void rb_tree_rotate(struct rb_tree *, struct rb_node *, int);
+static void rb_tree_insert_rebalance(struct rb_tree *, struct rb_node *);
+static void rb_tree_removal_rebalance(struct rb_tree *, struct rb_node *);
+
+/*
+ * Rather than testing for the NULL everywhere, all terminal leaves are
+ * pointed to this node. Note that by setting it to be const, that on
+ * some architectures trying to write to it will cause a fault.
+ */
+static const struct rb_node sentinel_node = {
+ NULL, NULL, NULL, { NULL, NULL }, 0, 0, 1
+};
+
+void
+rb_tree_init(struct rb_tree *rbt, rb_compare_nodes_fn compare_nodes,
+ rb_compare_key_fn compare_key, rb_print_node_fn print_node)
+{
+ TAILQ_INIT(&rbt->rbt_nodes);
+ rbt->rbt_count = 0;
+ rbt->rbt_compare_nodes = compare_nodes;
+ rbt->rbt_compare_key = compare_key;
+ rbt->rbt_print_node = print_node;
+ *((const struct rb_node **)&rbt->rbt_root) = &sentinel_node;
+}
+
+/*
+ * Rotate the tree between Y and X
+ * X c a Y
+ * a b b c
+ */
+void
+rb_tree_rotate(struct rb_tree *rbt, struct rb_node *self, int which)
+{
+ const int other = which ^ RB_OTHER;
+ struct rb_node * const parent = self->rb_parent;
+ struct rb_node * const child = self->rb_nodes[other];
+
+ assert(!child->rb_sentinel);
+ assert(child->rb_parent == self);
+#if 0
+ (*rbt->rbt_print_node)(child, which ? "before-l " : "before-r ");
+#endif
+
+ if ((child->rb_parent = parent) == NULL) {
+ assert(rbt->rbt_root == self);
+ rbt->rbt_root = child;
+ } else {
+ parent->rb_nodes[self->rb_position] = child;
+ }
+
+ self->rb_nodes[other] = child->rb_nodes[which];
+ if (!self->rb_nodes[other]->rb_sentinel)
+ self->rb_nodes[other]->rb_parent = self;
+ child->rb_nodes[which] = self;
+ child->rb_position = self->rb_position;
+ self->rb_parent = child;
+ self->rb_position = which;
+#if 0
+ (*rbt->rbt_print_node)(self, which ? "after-l " : "after-r ");
+#endif
+}
+
+void
+rb_tree_insert_node(struct rb_tree *rbt, struct rb_node *self)
+{
+ struct rb_node *prev, *next, *tmp, *parent;
+ struct rb_node **insert_p;
+ u_int position;
+
+ prev = NULL;
+ next = NULL;
+ parent = NULL;
+ tmp = rbt->rbt_root;
+
+ /*
+ * Find out where to place this new leaf.
+ */
+ while (!tmp->rb_sentinel) {
+ const int diff = (*rbt->rbt_compare_nodes)(tmp, self);
+ parent = tmp;
+ assert(diff != 0);
+ if (diff < 0) {
+ position = RB_LEFT;
+ next = parent->rb_left;
+ prev = NULL;
+ } else {
+ position = RB_RIGHT;
+ prev = parent->rb_right;
+ next = NULL;
+ }
+ tmp = parent->rb_nodes[position];
+ }
+
+ /*
+ * Verify our sequential position
+ */
+ if (prev != NULL && next == NULL)
+ next = TAILQ_NEXT(prev, rb_link);
+ if (prev == NULL && next != NULL)
+ next = TAILQ_PREV(next, rb_node_qh, rb_link);
+ assert(prev == NULL || (*rbt->rbt_compare_nodes)(prev, self) > 0);
+ assert(next == NULL || (*rbt->rbt_compare_nodes)(self, next) < 0);
+
+ /*
+ * Initialize the node and insert as a leaf into the tree.
+ */
+ rbt->rbt_count++;
+ self->rb_parent = parent;
+ if (parent == NULL) {
+ assert(rbt->rbt_root->rb_sentinel);
+ self->rb_position = RB_PARENT;
+ self->rb_left = rbt->rbt_root;
+ self->rb_right = rbt->rbt_root;
+ rbt->rbt_root = self;
+ } else {
+ self->rb_position = position;
+ self->rb_left = parent->rb_nodes[position];
+ self->rb_right = parent->rb_nodes[position];
+ parent->rb_nodes[position] = self;
+ }
+ assert(self->rb_left == &sentinel_node &&
+ self->rb_right == &sentinel_node);
+
+ /*
+ * Insert the new node into a sorted list for easy sequential access
+ */
+ if (next != NULL) {
+ TAILQ_INSERT_BEFORE(next, self, rb_link);
+ } else {
+ TAILQ_INSERT_TAIL(&rbt->rbt_nodes, self, rb_link);
+ }
+
+ /*
+ * Rebalance tree after insertation
+ */
+ rb_tree_insert_rebalance(rbt, self);
+}
+
+void
+rb_tree_insert_rebalance(struct rb_tree *rbt, struct rb_node *self)
+{
+ self->rb_red = 1;
+
+ while (self != rbt->rbt_root && self->rb_parent->rb_red) {
+ const int which =
+ (self->rb_parent == self->rb_parent->rb_parent->rb_left
+ ? RB_LEFT
+ : RB_RIGHT);
+ const int other = which ^ RB_OTHER;
+ struct rb_node *uncle;
+
+ assert(!self->rb_sentinel);
+ /*
+ * We are red, our are parent is red, and our
+ * grandparent is black.
+ */
+ uncle = self->rb_parent->rb_parent->rb_nodes[other];
+ if (uncle->rb_red) {
+ /*
+ * Case 1: our uncle is red
+ * Simply invert the colors of our parent and
+ * uncle and make our grandparent red. And
+ * then solve the problem up at his level.
+ */
+ uncle->rb_red = 0;
+ self->rb_parent->rb_red = 0;
+ self->rb_parent->rb_parent->rb_red = 1;
+ self = self->rb_parent->rb_parent;
+ } else {
+ /*
+ * Case 2&3: our uncle is black.
+ */
+ if (self == self->rb_parent->rb_nodes[other]) {
+ /*
+ * Case 2: we are on the same side as our uncle
+ * Rotate parent away from uncle so this
+ * case becomes case 3
+ */
+ self = self->rb_parent;
+ rb_tree_rotate(rbt, self, which);
+ }
+ /*
+ * Case 3: we are opposite a child of a black uncle.
+ * Change parent to black and grandparent to
+ * red. Rotate grandparent away from ourself.
+ */
+ self->rb_parent->rb_red = 0;
+ self->rb_parent->rb_parent->rb_red = 1;
+ rb_tree_rotate(rbt, self->rb_parent->rb_parent, other);
+ }
+ }
+
+ /*
+ * Final step: Set the root to black.
+ */
+ rbt->rbt_root->rb_red = 0;
+}
+
+struct rb_node *
+rb_tree_lookup(struct rb_tree *rbt, void *key)
+{
+ struct rb_node *parent = rbt->rbt_root;
+
+ while (!parent->rb_sentinel) {
+ const int diff = (*rbt->rbt_compare_key)(parent, key);
+ if (diff == 0)
+ return parent;
+ parent = parent->rb_nodes[diff > 0];
+ }
+
+ return NULL;
+}
+
+void
+rb_tree_remove_node(struct rb_tree *rbt, struct rb_node *self)
+{
+ struct rb_node *child;
+ /*
+ * Easy case, one or more children is NULL (leaf node or parent of
+ * leaf node).
+ */
+ if (self->rb_left->rb_sentinel || self->rb_left->rb_sentinel) {
+ const int which = (!self->rb_left->rb_sentinel ? RB_LEFT : RB_RIGHT);
+ child = self->rb_nodes[which];
+ if (self->rb_parent == NULL) {
+ rbt->rbt_root = child;
+ } else {
+ self->rb_parent->rb_nodes[self->rb_position] = child;
+ }
+ if (child->rb_sentinel)
+ child = self->rb_parent;
+ else
+ child->rb_parent = self->rb_parent;
+ } else {
+ struct rb_node *new_self;
+ child = self->rb_right;
+ while (!child->rb_left->rb_sentinel)
+ child = child->rb_left;
+ new_self = child;
+ assert(new_self == TAILQ_NEXT(self, rb_link));
+
+ /*
+ * Take new_self out of the tree (its only subnode can be on the
+ * right since we know the left subnode is NULL).
+ */
+ child->rb_parent->rb_left = child->rb_right;
+ if (!child->rb_right->rb_sentinel) {
+ child->rb_right->rb_parent = child->rb_parent;
+ child->rb_right->rb_position = RB_LEFT;
+ }
+
+ /*
+ * Take self out of the tree and insert new_self into its place.
+ */
+ new_self->rb_right = self->rb_right;
+ new_self->rb_left = self->rb_left;
+ if (!new_self->rb_right->rb_sentinel)
+ new_self->rb_right->rb_parent = new_self;
+ if (!new_self->rb_left->rb_sentinel)
+ new_self->rb_left->rb_parent = new_self;
+ new_self->rb_red = self->rb_red;
+ new_self->rb_parent = self->rb_parent;
+ /*
+ * Update parent
+ */
+ if (new_self->rb_parent == NULL) {
+ rbt->rbt_root = new_self;
+ } else {
+ new_self->rb_parent->rb_nodes[self->rb_position] = new_self;
+ }
+ }
+ TAILQ_REMOVE(&rbt->rbt_nodes, self, rb_link);
+ rbt->rbt_count--;
+
+ if (child != NULL) {
+ assert(!child->rb_sentinel);
+#if 0
+ (*rbt->rbt_print_node)(child, "before ");
+#endif
+ rb_tree_removal_rebalance(rbt, child);
+#if 0
+ (*rbt->rbt_print_node)(child, "after ");
+#endif
+ }
+}
+
+void
+rb_tree_removal_rebalance(struct rb_tree *rbt, struct rb_node *self)
+{
+ assert(!self->rb_sentinel);
+ while (self->rb_parent != NULL && !self->rb_red) {
+ struct rb_node *parent = self->rb_parent;
+ int which = (self == parent->rb_left) ? RB_LEFT : RB_RIGHT;
+ int other = which ^ RB_OTHER;
+ struct rb_node *sibling = parent->rb_nodes[other];
+
+ if (sibling->rb_red) {
+ sibling->rb_red = 0;
+ parent->rb_red = 1;
+ rb_tree_rotate(rbt, parent, which);
+ parent = self->rb_parent;
+ sibling = parent->rb_nodes[other];
+ }
+
+ if (sibling->rb_sentinel ||
+ (!sibling->rb_left->rb_red && !sibling->rb_right->rb_red)) {
+ sibling->rb_red = 1;
+ self = parent;
+ continue;
+ }
+
+ if (!sibling->rb_nodes[other]->rb_red) {
+ sibling->rb_nodes[which]->rb_red = 0;
+ sibling->rb_red = 1;
+ rb_tree_rotate(rbt, sibling, other);
+ parent = self->rb_parent;
+ sibling = parent->rb_nodes[other];
+ }
+
+ sibling->rb_red = parent->rb_red;
+ parent->rb_red = 0;
+ sibling->rb_nodes[other]->rb_red = 0;
+ rb_tree_rotate(rbt, parent, which);
+ break;
+ }
+}
diff --git a/sys/lib/libkern/rb.h b/sys/lib/libkern/rb.h
new file mode 100644
index 00000000000..e66499434b0
--- /dev/null
+++ b/sys/lib/libkern/rb.h
@@ -0,0 +1,80 @@
+/*-
+ * Copyright (c) 2001 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Matt Thomas <matt@3am-software.com>.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the NetBSD
+ * Foundation, Inc. and its contributors.
+ * 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ */
+#ifndef _LIBKERN_RB_H_
+#define _LIBKERN_RB_H_
+
+#include <sys/types.h>
+#include <sys/queue.h>
+
+struct rb_node {
+ struct rb_node *rb_nodes[3];
+#define RB_LEFT 0
+#define RB_RIGHT 1
+#define RB_OTHER 1
+#define RB_PARENT 2
+#define rb_left rb_nodes[RB_LEFT]
+#define rb_right rb_nodes[RB_RIGHT]
+#define rb_parent rb_nodes[RB_PARENT]
+ TAILQ_ENTRY(rb_node) rb_link;
+ int rb_balance : 16;
+ unsigned int rb_red : 1;
+ unsigned int rb_sentinel : 1;
+ unsigned int rb_position : 2;
+};
+
+TAILQ_HEAD(rb_node_qh, rb_node);
+
+typedef int (*rb_compare_nodes_fn)(const struct rb_node *,
+ const struct rb_node *);
+typedef int (*rb_compare_key_fn)(const struct rb_node *, const void *);
+typedef void (*rb_print_node_fn)(const struct rb_node *, const char *);
+
+struct rb_tree {
+ struct rb_node *rbt_root;
+ struct rb_node_qh rbt_nodes;
+ rb_compare_nodes_fn rbt_compare_nodes;
+ rb_compare_key_fn rbt_compare_key;
+ rb_print_node_fn rbt_print_node;
+ u_int rbt_count;
+};
+
+void rb_tree_init(struct rb_tree *, rb_compare_nodes_fn, rb_compare_key_fn,
+ rb_print_node_fn);
+void rb_tree_insert_node(struct rb_tree *, struct rb_node *);
+struct rb_node *rb_tree_find(struct rb_tree *, void *);
+void rb_tree_remove_node(struct rb_tree *, struct rb_node *);
+
+#endif /* _LIBKERN_RB_H_*/