kernel: Add tree.h and tree_subr.c port

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 1643 insertions, 0 deletions

diff --git a/sys/include/sys/tree.h b/sys/include/sys/tree.h
new file mode 100644
index 0000000..1054ade
--- /dev/null
+++ b/sys/include/sys/tree.h
@@ -0,0 +1,1005 @@
+/*	$OpenBSD: tree.h,v 1.31 2023/03/08 04:43:09 guenther Exp $	*/
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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	_SYS_TREE_H_
+#define	_SYS_TREE_H_
+
+#include <sys/types.h>
+#include <sys/cdefs.h>
+
+/*
+ * This file defines data structures for different types of trees:
+ * splay trees and red-black trees.
+ *
+ * A splay tree is a self-organizing data structure.  Every operation
+ * on the tree causes a splay to happen.  The splay moves the requested
+ * node to the root of the tree and partly rebalances it.
+ *
+ * This has the benefit that request locality causes faster lookups as
+ * the requested nodes move to the top of the tree.  On the other hand,
+ * every lookup causes memory writes.
+ *
+ * The Balance Theorem bounds the total access time for m operations
+ * and n inserts on an initially empty tree as O((m + n)lg n).  The
+ * amortized cost for a sequence of m accesses to a splay tree is O(lg n);
+ *
+ * A red-black tree is a binary search tree with the node color as an
+ * extra attribute.  It fulfills a set of conditions:
+ *	- every search path from the root to a leaf consists of the
+ *	  same number of black nodes,
+ *	- each red node (except for the root) has a black parent,
+ *	- each leaf node is black.
+ *
+ * Every operation on a red-black tree is bounded as O(lg n).
+ * The maximum height of a red-black tree is 2lg (n+1).
+ */
+
+#define SPLAY_HEAD(name, type)						\
+struct name {								\
+	struct type *sph_root; /* root of the tree */			\
+}
+
+#define SPLAY_INITIALIZER(root)						\
+	{ NULL }
+
+#define SPLAY_INIT(root) do {						\
+	(root)->sph_root = NULL;					\
+} while (0)
+
+#define SPLAY_ENTRY(type)						\
+struct {								\
+	struct type *spe_left; /* left element */			\
+	struct type *spe_right; /* right element */			\
+}
+
+#define SPLAY_LEFT(elm, field)		(elm)->field.spe_left
+#define SPLAY_RIGHT(elm, field)		(elm)->field.spe_right
+#define SPLAY_ROOT(head)		(head)->sph_root
+#define SPLAY_EMPTY(head)		(SPLAY_ROOT(head) == NULL)
+
+/* SPLAY_ROTATE_{LEFT,RIGHT} expect that tmp hold SPLAY_{RIGHT,LEFT} */
+#define SPLAY_ROTATE_RIGHT(head, tmp, field) do {			\
+	SPLAY_LEFT((head)->sph_root, field) = SPLAY_RIGHT(tmp, field);	\
+	SPLAY_RIGHT(tmp, field) = (head)->sph_root;			\
+	(head)->sph_root = tmp;						\
+} while (0)
+
+#define SPLAY_ROTATE_LEFT(head, tmp, field) do {			\
+	SPLAY_RIGHT((head)->sph_root, field) = SPLAY_LEFT(tmp, field);	\
+	SPLAY_LEFT(tmp, field) = (head)->sph_root;			\
+	(head)->sph_root = tmp;						\
+} while (0)
+
+#define SPLAY_LINKLEFT(head, tmp, field) do {				\
+	SPLAY_LEFT(tmp, field) = (head)->sph_root;			\
+	tmp = (head)->sph_root;						\
+	(head)->sph_root = SPLAY_LEFT((head)->sph_root, field);		\
+} while (0)
+
+#define SPLAY_LINKRIGHT(head, tmp, field) do {				\
+	SPLAY_RIGHT(tmp, field) = (head)->sph_root;			\
+	tmp = (head)->sph_root;						\
+	(head)->sph_root = SPLAY_RIGHT((head)->sph_root, field);	\
+} while (0)
+
+#define SPLAY_ASSEMBLE(head, node, left, right, field) do {		\
+	SPLAY_RIGHT(left, field) = SPLAY_LEFT((head)->sph_root, field);	\
+	SPLAY_LEFT(right, field) = SPLAY_RIGHT((head)->sph_root, field);\
+	SPLAY_LEFT((head)->sph_root, field) = SPLAY_RIGHT(node, field);	\
+	SPLAY_RIGHT((head)->sph_root, field) = SPLAY_LEFT(node, field);	\
+} while (0)
+
+/* Generates prototypes and inline functions */
+
+#define SPLAY_PROTOTYPE(name, type, field, cmp)				\
+void name##_SPLAY(struct name *, struct type *);			\
+void name##_SPLAY_MINMAX(struct name *, int);				\
+struct type *name##_SPLAY_INSERT(struct name *, struct type *);		\
+struct type *name##_SPLAY_REMOVE(struct name *, struct type *);		\
+									\
+/* Finds the node with the same key as elm */				\
+static __unused __inline struct type *					\
+name##_SPLAY_FIND(struct name *head, struct type *elm)			\
+{									\
+	if (SPLAY_EMPTY(head))						\
+		return(NULL);						\
+	name##_SPLAY(head, elm);					\
+	if ((cmp)(elm, (head)->sph_root) == 0)				\
+		return (head->sph_root);				\
+	return (NULL);							\
+}									\
+									\
+static __unused __inline struct type *					\
+name##_SPLAY_NEXT(struct name *head, struct type *elm)			\
+{									\
+	name##_SPLAY(head, elm);					\
+	if (SPLAY_RIGHT(elm, field) != NULL) {				\
+		elm = SPLAY_RIGHT(elm, field);				\
+		while (SPLAY_LEFT(elm, field) != NULL) {		\
+			elm = SPLAY_LEFT(elm, field);			\
+		}							\
+	} else								\
+		elm = NULL;						\
+	return (elm);							\
+}									\
+									\
+static __unused __inline struct type *					\
+name##_SPLAY_MIN_MAX(struct name *head, int val)			\
+{									\
+	name##_SPLAY_MINMAX(head, val);					\
+        return (SPLAY_ROOT(head));					\
+}
+
+/* Main splay operation.
+ * Moves node close to the key of elm to top
+ */
+#define SPLAY_GENERATE(name, type, field, cmp)				\
+struct type *								\
+name##_SPLAY_INSERT(struct name *head, struct type *elm)		\
+{									\
+    if (SPLAY_EMPTY(head)) {						\
+	    SPLAY_LEFT(elm, field) = SPLAY_RIGHT(elm, field) = NULL;	\
+    } else {								\
+	    int __comp;							\
+	    name##_SPLAY(head, elm);					\
+	    __comp = (cmp)(elm, (head)->sph_root);			\
+	    if(__comp < 0) {						\
+		    SPLAY_LEFT(elm, field) = SPLAY_LEFT((head)->sph_root, field);\
+		    SPLAY_RIGHT(elm, field) = (head)->sph_root;		\
+		    SPLAY_LEFT((head)->sph_root, field) = NULL;		\
+	    } else if (__comp > 0) {					\
+		    SPLAY_RIGHT(elm, field) = SPLAY_RIGHT((head)->sph_root, field);\
+		    SPLAY_LEFT(elm, field) = (head)->sph_root;		\
+		    SPLAY_RIGHT((head)->sph_root, field) = NULL;	\
+	    } else							\
+		    return ((head)->sph_root);				\
+    }									\
+    (head)->sph_root = (elm);						\
+    return (NULL);							\
+}									\
+									\
+struct type *								\
+name##_SPLAY_REMOVE(struct name *head, struct type *elm)		\
+{									\
+	struct type *__tmp;						\
+	if (SPLAY_EMPTY(head))						\
+		return (NULL);						\
+	name##_SPLAY(head, elm);					\
+	if ((cmp)(elm, (head)->sph_root) == 0) {			\
+		if (SPLAY_LEFT((head)->sph_root, field) == NULL) {	\
+			(head)->sph_root = SPLAY_RIGHT((head)->sph_root, field);\
+		} else {						\
+			__tmp = SPLAY_RIGHT((head)->sph_root, field);	\
+			(head)->sph_root = SPLAY_LEFT((head)->sph_root, field);\
+			name##_SPLAY(head, elm);			\
+			SPLAY_RIGHT((head)->sph_root, field) = __tmp;	\
+		}							\
+		return (elm);						\
+	}								\
+	return (NULL);							\
+}									\
+									\
+void									\
+name##_SPLAY(struct name *head, struct type *elm)			\
+{									\
+	struct type __node, *__left, *__right, *__tmp;			\
+	int __comp;							\
+\
+	SPLAY_LEFT(&__node, field) = SPLAY_RIGHT(&__node, field) = NULL;\
+	__left = __right = &__node;					\
+\
+	while ((__comp = (cmp)(elm, (head)->sph_root))) {		\
+		if (__comp < 0) {					\
+			__tmp = SPLAY_LEFT((head)->sph_root, field);	\
+			if (__tmp == NULL)				\
+				break;					\
+			if ((cmp)(elm, __tmp) < 0){			\
+				SPLAY_ROTATE_RIGHT(head, __tmp, field);	\
+				if (SPLAY_LEFT((head)->sph_root, field) == NULL)\
+					break;				\
+			}						\
+			SPLAY_LINKLEFT(head, __right, field);		\
+		} else if (__comp > 0) {				\
+			__tmp = SPLAY_RIGHT((head)->sph_root, field);	\
+			if (__tmp == NULL)				\
+				break;					\
+			if ((cmp)(elm, __tmp) > 0){			\
+				SPLAY_ROTATE_LEFT(head, __tmp, field);	\
+				if (SPLAY_RIGHT((head)->sph_root, field) == NULL)\
+					break;				\
+			}						\
+			SPLAY_LINKRIGHT(head, __left, field);		\
+		}							\
+	}								\
+	SPLAY_ASSEMBLE(head, &__node, __left, __right, field);		\
+}									\
+									\
+/* Splay with either the minimum or the maximum element			\
+ * Used to find minimum or maximum element in tree.			\
+ */									\
+void name##_SPLAY_MINMAX(struct name *head, int __comp) \
+{									\
+	struct type __node, *__left, *__right, *__tmp;			\
+\
+	SPLAY_LEFT(&__node, field) = SPLAY_RIGHT(&__node, field) = NULL;\
+	__left = __right = &__node;					\
+\
+	while (1) {							\
+		if (__comp < 0) {					\
+			__tmp = SPLAY_LEFT((head)->sph_root, field);	\
+			if (__tmp == NULL)				\
+				break;					\
+			if (__comp < 0){				\
+				SPLAY_ROTATE_RIGHT(head, __tmp, field);	\
+				if (SPLAY_LEFT((head)->sph_root, field) == NULL)\
+					break;				\
+			}						\
+			SPLAY_LINKLEFT(head, __right, field);		\
+		} else if (__comp > 0) {				\
+			__tmp = SPLAY_RIGHT((head)->sph_root, field);	\
+			if (__tmp == NULL)				\
+				break;					\
+			if (__comp > 0) {				\
+				SPLAY_ROTATE_LEFT(head, __tmp, field);	\
+				if (SPLAY_RIGHT((head)->sph_root, field) == NULL)\
+					break;				\
+			}						\
+			SPLAY_LINKRIGHT(head, __left, field);		\
+		}							\
+	}								\
+	SPLAY_ASSEMBLE(head, &__node, __left, __right, field);		\
+}
+
+#define SPLAY_NEGINF	-1
+#define SPLAY_INF	1
+
+#define SPLAY_INSERT(name, x, y)	name##_SPLAY_INSERT(x, y)
+#define SPLAY_REMOVE(name, x, y)	name##_SPLAY_REMOVE(x, y)
+#define SPLAY_FIND(name, x, y)		name##_SPLAY_FIND(x, y)
+#define SPLAY_NEXT(name, x, y)		name##_SPLAY_NEXT(x, y)
+#define SPLAY_MIN(name, x)		(SPLAY_EMPTY(x) ? NULL	\
+					: name##_SPLAY_MIN_MAX(x, SPLAY_NEGINF))
+#define SPLAY_MAX(name, x)		(SPLAY_EMPTY(x) ? NULL	\
+					: name##_SPLAY_MIN_MAX(x, SPLAY_INF))
+
+#define SPLAY_FOREACH(x, name, head)					\
+	for ((x) = SPLAY_MIN(name, head);				\
+	     (x) != NULL;						\
+	     (x) = SPLAY_NEXT(name, head, x))
+
+/* Macros that define a red-black tree */
+#define RB_HEAD(name, type)						\
+struct name {								\
+	struct type *rbh_root; /* root of the tree */			\
+}
+
+#define RB_INITIALIZER(root)						\
+	{ NULL }
+
+#define RB_INIT(root) do {						\
+	(root)->rbh_root = NULL;					\
+} while (0)
+
+#define RB_BLACK	0
+#define RB_RED		1
+#define RB_ENTRY(type)							\
+struct {								\
+	struct type *rbe_left;		/* left element */		\
+	struct type *rbe_right;		/* right element */		\
+	struct type *rbe_parent;	/* parent element */		\
+	int rbe_color;			/* node color */		\
+}
+
+#define RB_LEFT(elm, field)		(elm)->field.rbe_left
+#define RB_RIGHT(elm, field)		(elm)->field.rbe_right
+#define RB_PARENT(elm, field)		(elm)->field.rbe_parent
+#define RB_COLOR(elm, field)		(elm)->field.rbe_color
+#define RB_ROOT(head)			(head)->rbh_root
+#define RB_EMPTY(head)			(RB_ROOT(head) == NULL)
+
+#define RB_SET(elm, parent, field) do {					\
+	RB_PARENT(elm, field) = parent;					\
+	RB_LEFT(elm, field) = RB_RIGHT(elm, field) = NULL;		\
+	RB_COLOR(elm, field) = RB_RED;					\
+} while (0)
+
+#define RB_SET_BLACKRED(black, red, field) do {				\
+	RB_COLOR(black, field) = RB_BLACK;				\
+	RB_COLOR(red, field) = RB_RED;					\
+} while (0)
+
+#ifndef RB_AUGMENT
+#define RB_AUGMENT(x)	do {} while (0)
+#endif
+
+#define RB_ROTATE_LEFT(head, elm, tmp, field) do {			\
+	(tmp) = RB_RIGHT(elm, field);					\
+	if ((RB_RIGHT(elm, field) = RB_LEFT(tmp, field))) {		\
+		RB_PARENT(RB_LEFT(tmp, field), field) = (elm);		\
+	}								\
+	RB_AUGMENT(elm);						\
+	if ((RB_PARENT(tmp, field) = RB_PARENT(elm, field))) {		\
+		if ((elm) == RB_LEFT(RB_PARENT(elm, field), field))	\
+			RB_LEFT(RB_PARENT(elm, field), field) = (tmp);	\
+		else							\
+			RB_RIGHT(RB_PARENT(elm, field), field) = (tmp);	\
+	} else								\
+		(head)->rbh_root = (tmp);				\
+	RB_LEFT(tmp, field) = (elm);					\
+	RB_PARENT(elm, field) = (tmp);					\
+	RB_AUGMENT(tmp);						\
+	if ((RB_PARENT(tmp, field)))					\
+		RB_AUGMENT(RB_PARENT(tmp, field));			\
+} while (0)
+
+#define RB_ROTATE_RIGHT(head, elm, tmp, field) do {			\
+	(tmp) = RB_LEFT(elm, field);					\
+	if ((RB_LEFT(elm, field) = RB_RIGHT(tmp, field))) {		\
+		RB_PARENT(RB_RIGHT(tmp, field), field) = (elm);		\
+	}								\
+	RB_AUGMENT(elm);						\
+	if ((RB_PARENT(tmp, field) = RB_PARENT(elm, field))) {		\
+		if ((elm) == RB_LEFT(RB_PARENT(elm, field), field))	\
+			RB_LEFT(RB_PARENT(elm, field), field) = (tmp);	\
+		else							\
+			RB_RIGHT(RB_PARENT(elm, field), field) = (tmp);	\
+	} else								\
+		(head)->rbh_root = (tmp);				\
+	RB_RIGHT(tmp, field) = (elm);					\
+	RB_PARENT(elm, field) = (tmp);					\
+	RB_AUGMENT(tmp);						\
+	if ((RB_PARENT(tmp, field)))					\
+		RB_AUGMENT(RB_PARENT(tmp, field));			\
+} while (0)
+
+/* Generates prototypes and inline functions */
+#define	RB_PROTOTYPE(name, type, field, cmp)				\
+	RB_PROTOTYPE_INTERNAL(name, type, field, cmp,)
+#define	RB_PROTOTYPE_STATIC(name, type, field, cmp)			\
+	RB_PROTOTYPE_INTERNAL(name, type, field, cmp, __attribute__((__unused__)) static)
+#define RB_PROTOTYPE_INTERNAL(name, type, field, cmp, attr)		\
+attr void name##_RB_INSERT_COLOR(struct name *, struct type *);		\
+attr void name##_RB_REMOVE_COLOR(struct name *, struct type *, struct type *);\
+attr struct type *name##_RB_REMOVE(struct name *, struct type *);	\
+attr struct type *name##_RB_INSERT(struct name *, struct type *);	\
+attr struct type *name##_RB_FIND(struct name *, struct type *);		\
+attr struct type *name##_RB_NFIND(struct name *, struct type *);	\
+attr struct type *name##_RB_NEXT(struct type *);			\
+attr struct type *name##_RB_PREV(struct type *);			\
+attr struct type *name##_RB_MINMAX(struct name *, int);			\
+									\
+
+/* Main rb operation.
+ * Moves node close to the key of elm to top
+ */
+#define	RB_GENERATE(name, type, field, cmp)				\
+	RB_GENERATE_INTERNAL(name, type, field, cmp,)
+#define	RB_GENERATE_STATIC(name, type, field, cmp)			\
+	RB_GENERATE_INTERNAL(name, type, field, cmp, __attribute__((__unused__)) static)
+#define RB_GENERATE_INTERNAL(name, type, field, cmp, attr)		\
+attr void								\
+name##_RB_INSERT_COLOR(struct name *head, struct type *elm)		\
+{									\
+	struct type *parent, *gparent, *tmp;				\
+	while ((parent = RB_PARENT(elm, field)) &&			\
+	    RB_COLOR(parent, field) == RB_RED) {			\
+		gparent = RB_PARENT(parent, field);			\
+		if (parent == RB_LEFT(gparent, field)) {		\
+			tmp = RB_RIGHT(gparent, field);			\
+			if (tmp && RB_COLOR(tmp, field) == RB_RED) {	\
+				RB_COLOR(tmp, field) = RB_BLACK;	\
+				RB_SET_BLACKRED(parent, gparent, field);\
+				elm = gparent;				\
+				continue;				\
+			}						\
+			if (RB_RIGHT(parent, field) == elm) {		\
+				RB_ROTATE_LEFT(head, parent, tmp, field);\
+				tmp = parent;				\
+				parent = elm;				\
+				elm = tmp;				\
+			}						\
+			RB_SET_BLACKRED(parent, gparent, field);	\
+			RB_ROTATE_RIGHT(head, gparent, tmp, field);	\
+		} else {						\
+			tmp = RB_LEFT(gparent, field);			\
+			if (tmp && RB_COLOR(tmp, field) == RB_RED) {	\
+				RB_COLOR(tmp, field) = RB_BLACK;	\
+				RB_SET_BLACKRED(parent, gparent, field);\
+				elm = gparent;				\
+				continue;				\
+			}						\
+			if (RB_LEFT(parent, field) == elm) {		\
+				RB_ROTATE_RIGHT(head, parent, tmp, field);\
+				tmp = parent;				\
+				parent = elm;				\
+				elm = tmp;				\
+			}						\
+			RB_SET_BLACKRED(parent, gparent, field);	\
+			RB_ROTATE_LEFT(head, gparent, tmp, field);	\
+		}							\
+	}								\
+	RB_COLOR(head->rbh_root, field) = RB_BLACK;			\
+}									\
+									\
+attr void								\
+name##_RB_REMOVE_COLOR(struct name *head, struct type *parent, struct type *elm) \
+{									\
+	struct type *tmp;						\
+	while ((elm == NULL || RB_COLOR(elm, field) == RB_BLACK) &&	\
+	    elm != RB_ROOT(head)) {					\
+		if (RB_LEFT(parent, field) == elm) {			\
+			tmp = RB_RIGHT(parent, field);			\
+			if (RB_COLOR(tmp, field) == RB_RED) {		\
+				RB_SET_BLACKRED(tmp, parent, field);	\
+				RB_ROTATE_LEFT(head, parent, tmp, field);\
+				tmp = RB_RIGHT(parent, field);		\
+			}						\
+			if ((RB_LEFT(tmp, field) == NULL ||		\
+			    RB_COLOR(RB_LEFT(tmp, field), field) == RB_BLACK) &&\
+			    (RB_RIGHT(tmp, field) == NULL ||		\
+			    RB_COLOR(RB_RIGHT(tmp, field), field) == RB_BLACK)) {\
+				RB_COLOR(tmp, field) = RB_RED;		\
+				elm = parent;				\
+				parent = RB_PARENT(elm, field);		\
+			} else {					\
+				if (RB_RIGHT(tmp, field) == NULL ||	\
+				    RB_COLOR(RB_RIGHT(tmp, field), field) == RB_BLACK) {\
+					struct type *oleft;		\
+					if ((oleft = RB_LEFT(tmp, field)))\
+						RB_COLOR(oleft, field) = RB_BLACK;\
+					RB_COLOR(tmp, field) = RB_RED;	\
+					RB_ROTATE_RIGHT(head, tmp, oleft, field);\
+					tmp = RB_RIGHT(parent, field);	\
+				}					\
+				RB_COLOR(tmp, field) = RB_COLOR(parent, field);\
+				RB_COLOR(parent, field) = RB_BLACK;	\
+				if (RB_RIGHT(tmp, field))		\
+					RB_COLOR(RB_RIGHT(tmp, field), field) = RB_BLACK;\
+				RB_ROTATE_LEFT(head, parent, tmp, field);\
+				elm = RB_ROOT(head);			\
+				break;					\
+			}						\
+		} else {						\
+			tmp = RB_LEFT(parent, field);			\
+			if (RB_COLOR(tmp, field) == RB_RED) {		\
+				RB_SET_BLACKRED(tmp, parent, field);	\
+				RB_ROTATE_RIGHT(head, parent, tmp, field);\
+				tmp = RB_LEFT(parent, field);		\
+			}						\
+			if ((RB_LEFT(tmp, field) == NULL ||		\
+			    RB_COLOR(RB_LEFT(tmp, field), field) == RB_BLACK) &&\
+			    (RB_RIGHT(tmp, field) == NULL ||		\
+			    RB_COLOR(RB_RIGHT(tmp, field), field) == RB_BLACK)) {\
+				RB_COLOR(tmp, field) = RB_RED;		\
+				elm = parent;				\
+				parent = RB_PARENT(elm, field);		\
+			} else {					\
+				if (RB_LEFT(tmp, field) == NULL ||	\
+				    RB_COLOR(RB_LEFT(tmp, field), field) == RB_BLACK) {\
+					struct type *oright;		\
+					if ((oright = RB_RIGHT(tmp, field)))\
+						RB_COLOR(oright, field) = RB_BLACK;\
+					RB_COLOR(tmp, field) = RB_RED;	\
+					RB_ROTATE_LEFT(head, tmp, oright, field);\
+					tmp = RB_LEFT(parent, field);	\
+				}					\
+				RB_COLOR(tmp, field) = RB_COLOR(parent, field);\
+				RB_COLOR(parent, field) = RB_BLACK;	\
+				if (RB_LEFT(tmp, field))		\
+					RB_COLOR(RB_LEFT(tmp, field), field) = RB_BLACK;\
+				RB_ROTATE_RIGHT(head, parent, tmp, field);\
+				elm = RB_ROOT(head);			\
+				break;					\
+			}						\
+		}							\
+	}								\
+	if (elm)							\
+		RB_COLOR(elm, field) = RB_BLACK;			\
+}									\
+									\
+attr struct type *							\
+name##_RB_REMOVE(struct name *head, struct type *elm)			\
+{									\
+	struct type *child, *parent, *old = elm;			\
+	int color;							\
+	if (RB_LEFT(elm, field) == NULL)				\
+		child = RB_RIGHT(elm, field);				\
+	else if (RB_RIGHT(elm, field) == NULL)				\
+		child = RB_LEFT(elm, field);				\
+	else {								\
+		struct type *left;					\
+		elm = RB_RIGHT(elm, field);				\
+		while ((left = RB_LEFT(elm, field)))			\
+			elm = left;					\
+		child = RB_RIGHT(elm, field);				\
+		parent = RB_PARENT(elm, field);				\
+		color = RB_COLOR(elm, field);				\
+		if (child)						\
+			RB_PARENT(child, field) = parent;		\
+		if (parent) {						\
+			if (RB_LEFT(parent, field) == elm)		\
+				RB_LEFT(parent, field) = child;		\
+			else						\
+				RB_RIGHT(parent, field) = child;	\
+			RB_AUGMENT(parent);				\
+		} else							\
+			RB_ROOT(head) = child;				\
+		if (RB_PARENT(elm, field) == old)			\
+			parent = elm;					\
+		(elm)->field = (old)->field;				\
+		if (RB_PARENT(old, field)) {				\
+			if (RB_LEFT(RB_PARENT(old, field), field) == old)\
+				RB_LEFT(RB_PARENT(old, field), field) = elm;\
+			else						\
+				RB_RIGHT(RB_PARENT(old, field), field) = elm;\
+			RB_AUGMENT(RB_PARENT(old, field));		\
+		} else							\
+			RB_ROOT(head) = elm;				\
+		RB_PARENT(RB_LEFT(old, field), field) = elm;		\
+		if (RB_RIGHT(old, field))				\
+			RB_PARENT(RB_RIGHT(old, field), field) = elm;	\
+		if (parent) {						\
+			left = parent;					\
+			do {						\
+				RB_AUGMENT(left);			\
+			} while ((left = RB_PARENT(left, field)));	\
+		}							\
+		goto color;						\
+	}								\
+	parent = RB_PARENT(elm, field);					\
+	color = RB_COLOR(elm, field);					\
+	if (child)							\
+		RB_PARENT(child, field) = parent;			\
+	if (parent) {							\
+		if (RB_LEFT(parent, field) == elm)			\
+			RB_LEFT(parent, field) = child;			\
+		else							\
+			RB_RIGHT(parent, field) = child;		\
+		RB_AUGMENT(parent);					\
+	} else								\
+		RB_ROOT(head) = child;					\
+color:									\
+	if (color == RB_BLACK)						\
+		name##_RB_REMOVE_COLOR(head, parent, child);		\
+	return (old);							\
+}									\
+									\
+/* Inserts a node into the RB tree */					\
+attr struct type *							\
+name##_RB_INSERT(struct name *head, struct type *elm)			\
+{									\
+	struct type *tmp;						\
+	struct type *parent = NULL;					\
+	int comp = 0;							\
+	tmp = RB_ROOT(head);						\
+	while (tmp) {							\
+		parent = tmp;						\
+		comp = (cmp)(elm, parent);				\
+		if (comp < 0)						\
+			tmp = RB_LEFT(tmp, field);			\
+		else if (comp > 0)					\
+			tmp = RB_RIGHT(tmp, field);			\
+		else							\
+			return (tmp);					\
+	}								\
+	RB_SET(elm, parent, field);					\
+	if (parent != NULL) {						\
+		if (comp < 0)						\
+			RB_LEFT(parent, field) = elm;			\
+		else							\
+			RB_RIGHT(parent, field) = elm;			\
+		RB_AUGMENT(parent);					\
+	} else								\
+		RB_ROOT(head) = elm;					\
+	name##_RB_INSERT_COLOR(head, elm);				\
+	return (NULL);							\
+}									\
+									\
+/* Finds the node with the same key as elm */				\
+attr struct type *							\
+name##_RB_FIND(struct name *head, struct type *elm)			\
+{									\
+	struct type *tmp = RB_ROOT(head);				\
+	int comp;							\
+	while (tmp) {							\
+		comp = cmp(elm, tmp);					\
+		if (comp < 0)						\
+			tmp = RB_LEFT(tmp, field);			\
+		else if (comp > 0)					\
+			tmp = RB_RIGHT(tmp, field);			\
+		else							\
+			return (tmp);					\
+	}								\
+	return (NULL);							\
+}									\
+									\
+/* Finds the first node greater than or equal to the search key */	\
+attr struct type *							\
+name##_RB_NFIND(struct name *head, struct type *elm)			\
+{									\
+	struct type *tmp = RB_ROOT(head);				\
+	struct type *res = NULL;					\
+	int comp;							\
+	while (tmp) {							\
+		comp = cmp(elm, tmp);					\
+		if (comp < 0) {						\
+			res = tmp;					\
+			tmp = RB_LEFT(tmp, field);			\
+		}							\
+		else if (comp > 0)					\
+			tmp = RB_RIGHT(tmp, field);			\
+		else							\
+			return (tmp);					\
+	}								\
+	return (res);							\
+}									\
+									\
+attr struct type *							\
+name##_RB_NEXT(struct type *elm)					\
+{									\
+	if (RB_RIGHT(elm, field)) {					\
+		elm = RB_RIGHT(elm, field);				\
+		while (RB_LEFT(elm, field))				\
+			elm = RB_LEFT(elm, field);			\
+	} else {							\
+		if (RB_PARENT(elm, field) &&				\
+		    (elm == RB_LEFT(RB_PARENT(elm, field), field)))	\
+			elm = RB_PARENT(elm, field);			\
+		else {							\
+			while (RB_PARENT(elm, field) &&			\
+			    (elm == RB_RIGHT(RB_PARENT(elm, field), field)))\
+				elm = RB_PARENT(elm, field);		\
+			elm = RB_PARENT(elm, field);			\
+		}							\
+	}								\
+	return (elm);							\
+}									\
+									\
+attr struct type *							\
+name##_RB_PREV(struct type *elm)					\
+{									\
+	if (RB_LEFT(elm, field)) {					\
+		elm = RB_LEFT(elm, field);				\
+		while (RB_RIGHT(elm, field))				\
+			elm = RB_RIGHT(elm, field);			\
+	} else {							\
+		if (RB_PARENT(elm, field) &&				\
+		    (elm == RB_RIGHT(RB_PARENT(elm, field), field)))	\
+			elm = RB_PARENT(elm, field);			\
+		else {							\
+			while (RB_PARENT(elm, field) &&			\
+			    (elm == RB_LEFT(RB_PARENT(elm, field), field)))\
+				elm = RB_PARENT(elm, field);		\
+			elm = RB_PARENT(elm, field);			\
+		}							\
+	}								\
+	return (elm);							\
+}									\
+									\
+attr struct type *							\
+name##_RB_MINMAX(struct name *head, int val)				\
+{									\
+	struct type *tmp = RB_ROOT(head);				\
+	struct type *parent = NULL;					\
+	while (tmp) {							\
+		parent = tmp;						\
+		if (val < 0)						\
+			tmp = RB_LEFT(tmp, field);			\
+		else							\
+			tmp = RB_RIGHT(tmp, field);			\
+	}								\
+	return (parent);						\
+}
+
+#define RB_NEGINF	-1
+#define RB_INF	1
+
+#define RB_INSERT(name, x, y)	name##_RB_INSERT(x, y)
+#define RB_REMOVE(name, x, y)	name##_RB_REMOVE(x, y)
+#define RB_FIND(name, x, y)	name##_RB_FIND(x, y)
+#define RB_NFIND(name, x, y)	name##_RB_NFIND(x, y)
+#define RB_NEXT(name, x, y)	name##_RB_NEXT(y)
+#define RB_PREV(name, x, y)	name##_RB_PREV(y)
+#define RB_MIN(name, x)		name##_RB_MINMAX(x, RB_NEGINF)
+#define RB_MAX(name, x)		name##_RB_MINMAX(x, RB_INF)
+
+#define RB_FOREACH(x, name, head)					\
+	for ((x) = RB_MIN(name, head);					\
+	     (x) != NULL;						\
+	     (x) = name##_RB_NEXT(x))
+
+#define RB_FOREACH_SAFE(x, name, head, y)				\
+	for ((x) = RB_MIN(name, head);					\
+	    ((x) != NULL) && ((y) = name##_RB_NEXT(x), 1);		\
+	     (x) = (y))
+
+#define RB_FOREACH_REVERSE(x, name, head)				\
+	for ((x) = RB_MAX(name, head);					\
+	     (x) != NULL;						\
+	     (x) = name##_RB_PREV(x))
+
+#define RB_FOREACH_REVERSE_SAFE(x, name, head, y)			\
+	for ((x) = RB_MAX(name, head);					\
+	    ((x) != NULL) && ((y) = name##_RB_PREV(x), 1);		\
+	     (x) = (y))
+
+
+/*
+ * Copyright (c) 2016 David Gwynne <dlg@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+struct rb_type {
+	int		(*t_compare)(const void *, const void *);
+	void		(*t_augment)(void *);
+	unsigned int	  t_offset;	/* offset of rb_entry in type */
+};
+
+struct rb_tree {
+	struct rb_entry	*rbt_root;
+};
+
+struct rb_entry {
+	struct rb_entry	 *rbt_parent;
+	struct rb_entry	 *rbt_left;
+	struct rb_entry	 *rbt_right;
+	unsigned int	  rbt_color;
+};
+
+#define RBT_HEAD(_name, _type)						\
+struct _name {								\
+	struct rb_tree rbh_root;					\
+}
+
+#define RBT_ENTRY(_type)	struct rb_entry
+
+static inline void
+_rb_init(struct rb_tree *rbt)
+{
+	rbt->rbt_root = NULL;
+}
+
+static inline int
+_rb_empty(struct rb_tree *rbt)
+{
+	return (rbt->rbt_root == NULL);
+}
+
+void	*_rb_insert(const struct rb_type *, struct rb_tree *, void *);
+void	*_rb_remove(const struct rb_type *, struct rb_tree *, void *);
+void	*_rb_find(const struct rb_type *, struct rb_tree *, const void *);
+void	*_rb_nfind(const struct rb_type *, struct rb_tree *, const void *);
+void	*_rb_root(const struct rb_type *, struct rb_tree *);
+void	*_rb_min(const struct rb_type *, struct rb_tree *);
+void	*_rb_max(const struct rb_type *, struct rb_tree *);
+void	*_rb_next(const struct rb_type *, void *);
+void	*_rb_prev(const struct rb_type *, void *);
+void	*_rb_left(const struct rb_type *, void *);
+void	*_rb_right(const struct rb_type *, void *);
+void	*_rb_parent(const struct rb_type *, void *);
+void	 _rb_set_left(const struct rb_type *, void *, void *);
+void	 _rb_set_right(const struct rb_type *, void *, void *);
+void	 _rb_set_parent(const struct rb_type *, void *, void *);
+void	 _rb_poison(const struct rb_type *, void *, unsigned long);
+int	 _rb_check(const struct rb_type *, void *, unsigned long);
+
+#define RBT_INITIALIZER(_head)	{ { NULL } }
+
+#define RBT_PROTOTYPE(_name, _type, _field, _cmp)			\
+extern const struct rb_type *const _name##_RBT_TYPE;			\
+									\
+__unused static inline void						\
+_name##_RBT_INIT(struct _name *head)					\
+{									\
+	_rb_init(&head->rbh_root);					\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_INSERT(struct _name *head, struct _type *elm)		\
+{									\
+	return _rb_insert(_name##_RBT_TYPE, &head->rbh_root, elm);	\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_REMOVE(struct _name *head, struct _type *elm)		\
+{									\
+	return _rb_remove(_name##_RBT_TYPE, &head->rbh_root, elm);	\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_FIND(struct _name *head, const struct _type *key)		\
+{									\
+	return _rb_find(_name##_RBT_TYPE, &head->rbh_root, key);	\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_NFIND(struct _name *head, const struct _type *key)		\
+{									\
+	return _rb_nfind(_name##_RBT_TYPE, &head->rbh_root, key);	\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_ROOT(struct _name *head)					\
+{									\
+	return _rb_root(_name##_RBT_TYPE, &head->rbh_root);		\
+}									\
+									\
+__unused static inline int						\
+_name##_RBT_EMPTY(struct _name *head)					\
+{									\
+	return _rb_empty(&head->rbh_root);				\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_MIN(struct _name *head)					\
+{									\
+	return _rb_min(_name##_RBT_TYPE, &head->rbh_root);		\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_MAX(struct _name *head)					\
+{									\
+	return _rb_max(_name##_RBT_TYPE, &head->rbh_root);		\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_NEXT(struct _type *elm)					\
+{									\
+	return _rb_next(_name##_RBT_TYPE, elm);				\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_PREV(struct _type *elm)					\
+{									\
+	return _rb_prev(_name##_RBT_TYPE, elm);				\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_LEFT(struct _type *elm)					\
+{									\
+	return _rb_left(_name##_RBT_TYPE, elm);				\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_RIGHT(struct _type *elm)					\
+{									\
+	return _rb_right(_name##_RBT_TYPE, elm);			\
+}									\
+									\
+__unused static inline struct _type *					\
+_name##_RBT_PARENT(struct _type *elm)					\
+{									\
+	return _rb_parent(_name##_RBT_TYPE, elm);			\
+}									\
+									\
+__unused static inline void						\
+_name##_RBT_SET_LEFT(struct _type *elm, struct _type *left)		\
+{									\
+	_rb_set_left(_name##_RBT_TYPE, elm, left);			\
+}									\
+									\
+__unused static inline void						\
+_name##_RBT_SET_RIGHT(struct _type *elm, struct _type *right)		\
+{									\
+	_rb_set_right(_name##_RBT_TYPE, elm, right);			\
+}									\
+									\
+__unused static inline void						\
+_name##_RBT_SET_PARENT(struct _type *elm, struct _type *parent)		\
+{									\
+	_rb_set_parent(_name##_RBT_TYPE, elm, parent);			\
+}									\
+									\
+__unused static inline void						\
+_name##_RBT_POISON(struct _type *elm, unsigned long poison)		\
+{									\
+	_rb_poison(_name##_RBT_TYPE, elm, poison);			\
+}									\
+									\
+__unused static inline int						\
+_name##_RBT_CHECK(struct _type *elm, unsigned long poison)		\
+{									\
+	return _rb_check(_name##_RBT_TYPE, elm, poison);		\
+}
+
+#define RBT_GENERATE_INTERNAL(_name, _type, _field, _cmp, _aug)		\
+static int								\
+_name##_RBT_COMPARE(const void *lptr, const void *rptr)			\
+{									\
+	const struct _type *l = lptr, *r = rptr;			\
+	return _cmp(l, r);						\
+}									\
+static const struct rb_type _name##_RBT_INFO = {			\
+	_name##_RBT_COMPARE,						\
+	_aug,								\
+	offsetof(struct _type, _field),					\
+};									\
+const struct rb_type *const _name##_RBT_TYPE = &_name##_RBT_INFO
+
+#define RBT_GENERATE_AUGMENT(_name, _type, _field, _cmp, _aug)		\
+static void								\
+_name##_RBT_AUGMENT(void *ptr)						\
+{									\
+	struct _type *p = ptr;						\
+	return _aug(p);							\
+}									\
+RBT_GENERATE_INTERNAL(_name, _type, _field, _cmp, _name##_RBT_AUGMENT)
+
+#define RBT_GENERATE(_name, _type, _field, _cmp)			\
+    RBT_GENERATE_INTERNAL(_name, _type, _field, _cmp, NULL)
+
+#define RBT_INIT(_name, _head)		_name##_RBT_INIT(_head)
+#define RBT_INSERT(_name, _head, _elm)	_name##_RBT_INSERT(_head, _elm)
+#define RBT_REMOVE(_name, _head, _elm)	_name##_RBT_REMOVE(_head, _elm)
+#define RBT_FIND(_name, _head, _key)	_name##_RBT_FIND(_head, _key)
+#define RBT_NFIND(_name, _head, _key)	_name##_RBT_NFIND(_head, _key)
+#define RBT_ROOT(_name, _head)		_name##_RBT_ROOT(_head)
+#define RBT_EMPTY(_name, _head)		_name##_RBT_EMPTY(_head)
+#define RBT_MIN(_name, _head)		_name##_RBT_MIN(_head)
+#define RBT_MAX(_name, _head)		_name##_RBT_MAX(_head)
+#define RBT_NEXT(_name, _elm)		_name##_RBT_NEXT(_elm)
+#define RBT_PREV(_name, _elm)		_name##_RBT_PREV(_elm)
+#define RBT_LEFT(_name, _elm)		_name##_RBT_LEFT(_elm)
+#define RBT_RIGHT(_name, _elm)		_name##_RBT_RIGHT(_elm)
+#define RBT_PARENT(_name, _elm)		_name##_RBT_PARENT(_elm)
+#define RBT_SET_LEFT(_name, _elm, _l)	_name##_RBT_SET_LEFT(_elm, _l)
+#define RBT_SET_RIGHT(_name, _elm, _r)	_name##_RBT_SET_RIGHT(_elm, _r)
+#define RBT_SET_PARENT(_name, _elm, _p)	_name##_RBT_SET_PARENT(_elm, _p)
+#define RBT_POISON(_name, _elm, _p)	_name##_RBT_POISON(_elm, _p)
+#define RBT_CHECK(_name, _elm, _p)	_name##_RBT_CHECK(_elm, _p)
+
+#define RBT_FOREACH(_e, _name, _head)					\
+	for ((_e) = RBT_MIN(_name, (_head));				\
+	     (_e) != NULL;						\
+	     (_e) = RBT_NEXT(_name, (_e)))
+
+#define RBT_FOREACH_SAFE(_e, _name, _head, _n)				\
+	for ((_e) = RBT_MIN(_name, (_head));				\
+	     (_e) != NULL && ((_n) = RBT_NEXT(_name, (_e)), 1);	\
+	     (_e) = (_n))
+
+#define RBT_FOREACH_REVERSE(_e, _name, _head)				\
+	for ((_e) = RBT_MAX(_name, (_head));				\
+	     (_e) != NULL;						\
+	     (_e) = RBT_PREV(_name, (_e)))
+
+#define RBT_FOREACH_REVERSE_SAFE(_e, _name, _head, _n)			\
+	for ((_e) = RBT_MAX(_name, (_head));				\
+	     (_e) != NULL && ((_n) = RBT_PREV(_name, (_e)), 1);	\
+	     (_e) = (_n))
+
+#endif	/* _SYS_TREE_H_ */
diff --git a/sys/kern/subr_tree.c b/sys/kern/subr_tree.c
new file mode 100644
index 0000000..63eda78
--- /dev/null
+++ b/sys/kern/subr_tree.c
@@ -0,0 +1,638 @@
+/*	$OpenBSD: subr_tree.c,v 1.10 2018/10/09 08:28:43 dlg Exp $ */
+
+/*
+ * Copyright 2002 Niels Provos <provos@citi.umich.edu>
+ * All rights reserved.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
+ */
+
+/*
+ * Copyright (c) 2016 David Gwynne <dlg@openbsd.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/tree.h>
+
+static inline struct rb_entry *
+rb_n2e(const struct rb_type *t, void *node)
+{
+	unsigned long addr = (unsigned long)node;
+
+	return ((struct rb_entry *)(addr + t->t_offset));
+}
+
+static inline void *
+rb_e2n(const struct rb_type *t, struct rb_entry *rbe)
+{
+	unsigned long addr = (unsigned long)rbe;
+
+	return ((void *)(addr - t->t_offset));
+}
+
+#define RBE_LEFT(_rbe)		(_rbe)->rbt_left
+#define RBE_RIGHT(_rbe)		(_rbe)->rbt_right
+#define RBE_PARENT(_rbe)	(_rbe)->rbt_parent
+#define RBE_COLOR(_rbe)		(_rbe)->rbt_color
+
+#define RBH_ROOT(_rbt)		(_rbt)->rbt_root
+
+static inline void
+rbe_set(struct rb_entry *rbe, struct rb_entry *parent)
+{
+	RBE_PARENT(rbe) = parent;
+	RBE_LEFT(rbe) = RBE_RIGHT(rbe) = NULL;
+	RBE_COLOR(rbe) = RB_RED;
+}
+
+static inline void
+rbe_set_blackred(struct rb_entry *black, struct rb_entry *red)
+{
+	RBE_COLOR(black) = RB_BLACK;
+	RBE_COLOR(red) = RB_RED;
+}
+
+static inline void
+rbe_augment(const struct rb_type *t, struct rb_entry *rbe)
+{
+	(*t->t_augment)(rb_e2n(t, rbe));
+}
+
+static inline void
+rbe_if_augment(const struct rb_type *t, struct rb_entry *rbe)
+{
+	if (t->t_augment != NULL)
+		rbe_augment(t, rbe);
+}
+
+static inline void
+rbe_rotate_left(const struct rb_type *t, struct rb_tree *rbt,
+    struct rb_entry *rbe)
+{
+	struct rb_entry *parent;
+	struct rb_entry *tmp;
+
+	tmp = RBE_RIGHT(rbe);
+	RBE_RIGHT(rbe) = RBE_LEFT(tmp);
+	if (RBE_RIGHT(rbe) != NULL)
+		RBE_PARENT(RBE_LEFT(tmp)) = rbe;
+
+	parent = RBE_PARENT(rbe);
+	RBE_PARENT(tmp) = parent;
+	if (parent != NULL) {
+		if (rbe == RBE_LEFT(parent))
+			RBE_LEFT(parent) = tmp;
+		else
+			RBE_RIGHT(parent) = tmp;
+	} else
+		RBH_ROOT(rbt) = tmp;
+
+	RBE_LEFT(tmp) = rbe;
+	RBE_PARENT(rbe) = tmp;
+
+	if (t->t_augment != NULL) {
+		rbe_augment(t, rbe);
+		rbe_augment(t, tmp);
+		parent = RBE_PARENT(tmp);
+		if (parent != NULL)
+			rbe_augment(t, parent);
+	}
+}
+
+static inline void
+rbe_rotate_right(const struct rb_type *t, struct rb_tree *rbt,
+    struct rb_entry *rbe)
+{
+	struct rb_entry *parent;
+	struct rb_entry *tmp;
+
+	tmp = RBE_LEFT(rbe);
+	RBE_LEFT(rbe) = RBE_RIGHT(tmp);
+	if (RBE_LEFT(rbe) != NULL)
+		RBE_PARENT(RBE_RIGHT(tmp)) = rbe;
+
+	parent = RBE_PARENT(rbe);
+	RBE_PARENT(tmp) = parent;
+	if (parent != NULL) {
+		if (rbe == RBE_LEFT(parent))
+			RBE_LEFT(parent) = tmp;
+		else
+			RBE_RIGHT(parent) = tmp;
+	} else
+		RBH_ROOT(rbt) = tmp;
+
+	RBE_RIGHT(tmp) = rbe;
+	RBE_PARENT(rbe) = tmp;
+
+	if (t->t_augment != NULL) {
+		rbe_augment(t, rbe);
+		rbe_augment(t, tmp);
+		parent = RBE_PARENT(tmp);
+		if (parent != NULL)
+			rbe_augment(t, parent);
+	}
+}
+
+static inline void
+rbe_insert_color(const struct rb_type *t, struct rb_tree *rbt,
+    struct rb_entry *rbe)
+{
+	struct rb_entry *parent, *gparent, *tmp;
+
+	while ((parent = RBE_PARENT(rbe)) != NULL &&
+	    RBE_COLOR(parent) == RB_RED) {
+		gparent = RBE_PARENT(parent);
+
+		if (parent == RBE_LEFT(gparent)) {
+			tmp = RBE_RIGHT(gparent);
+			if (tmp != NULL && RBE_COLOR(tmp) == RB_RED) {
+				RBE_COLOR(tmp) = RB_BLACK;
+				rbe_set_blackred(parent, gparent);
+				rbe = gparent;
+				continue;
+			}
+
+			if (RBE_RIGHT(parent) == rbe) {
+				rbe_rotate_left(t, rbt, parent);
+				tmp = parent;
+				parent = rbe;
+				rbe = tmp;
+			}
+
+			rbe_set_blackred(parent, gparent);
+			rbe_rotate_right(t, rbt, gparent);
+		} else {
+			tmp = RBE_LEFT(gparent);
+			if (tmp != NULL && RBE_COLOR(tmp) == RB_RED) {
+				RBE_COLOR(tmp) = RB_BLACK;
+				rbe_set_blackred(parent, gparent);
+				rbe = gparent;
+				continue;
+			}
+
+			if (RBE_LEFT(parent) == rbe) {
+				rbe_rotate_right(t, rbt, parent);
+				tmp = parent;
+				parent = rbe;
+				rbe = tmp;
+			}
+
+			rbe_set_blackred(parent, gparent);
+			rbe_rotate_left(t, rbt, gparent);
+		}
+	}
+
+	RBE_COLOR(RBH_ROOT(rbt)) = RB_BLACK;
+}
+
+static inline void
+rbe_remove_color(const struct rb_type *t, struct rb_tree *rbt,
+    struct rb_entry *parent, struct rb_entry *rbe)
+{
+	struct rb_entry *tmp;
+
+	while ((rbe == NULL || RBE_COLOR(rbe) == RB_BLACK) &&
+	    rbe != RBH_ROOT(rbt)) {
+		if (RBE_LEFT(parent) == rbe) {
+			tmp = RBE_RIGHT(parent);
+			if (RBE_COLOR(tmp) == RB_RED) {
+				rbe_set_blackred(tmp, parent);
+				rbe_rotate_left(t, rbt, parent);
+				tmp = RBE_RIGHT(parent);
+			}
+			if ((RBE_LEFT(tmp) == NULL ||
+			     RBE_COLOR(RBE_LEFT(tmp)) == RB_BLACK) &&
+			    (RBE_RIGHT(tmp) == NULL ||
+			     RBE_COLOR(RBE_RIGHT(tmp)) == RB_BLACK)) {
+				RBE_COLOR(tmp) = RB_RED;
+				rbe = parent;
+				parent = RBE_PARENT(rbe);
+			} else {
+				if (RBE_RIGHT(tmp) == NULL ||
+				    RBE_COLOR(RBE_RIGHT(tmp)) == RB_BLACK) {
+					struct rb_entry *oleft;
+
+					oleft = RBE_LEFT(tmp);
+					if (oleft != NULL)
+						RBE_COLOR(oleft) = RB_BLACK;
+
+					RBE_COLOR(tmp) = RB_RED;
+					rbe_rotate_right(t, rbt, tmp);
+					tmp = RBE_RIGHT(parent);
+				}
+
+				RBE_COLOR(tmp) = RBE_COLOR(parent);
+				RBE_COLOR(parent) = RB_BLACK;
+				if (RBE_RIGHT(tmp))
+					RBE_COLOR(RBE_RIGHT(tmp)) = RB_BLACK;
+
+				rbe_rotate_left(t, rbt, parent);
+				rbe = RBH_ROOT(rbt);
+				break;
+			}
+		} else {
+			tmp = RBE_LEFT(parent);
+			if (RBE_COLOR(tmp) == RB_RED) {
+				rbe_set_blackred(tmp, parent);
+				rbe_rotate_right(t, rbt, parent);
+				tmp = RBE_LEFT(parent);
+			}
+
+			if ((RBE_LEFT(tmp) == NULL ||
+			     RBE_COLOR(RBE_LEFT(tmp)) == RB_BLACK) &&
+			    (RBE_RIGHT(tmp) == NULL ||
+			     RBE_COLOR(RBE_RIGHT(tmp)) == RB_BLACK)) {
+				RBE_COLOR(tmp) = RB_RED;
+				rbe = parent;
+				parent = RBE_PARENT(rbe);
+			} else {
+				if (RBE_LEFT(tmp) == NULL ||
+				    RBE_COLOR(RBE_LEFT(tmp)) == RB_BLACK) {
+					struct rb_entry *oright;
+
+					oright = RBE_RIGHT(tmp);
+					if (oright != NULL)
+						RBE_COLOR(oright) = RB_BLACK;
+
+					RBE_COLOR(tmp) = RB_RED;
+					rbe_rotate_left(t, rbt, tmp);
+					tmp = RBE_LEFT(parent);
+				}
+
+				RBE_COLOR(tmp) = RBE_COLOR(parent);
+				RBE_COLOR(parent) = RB_BLACK;
+				if (RBE_LEFT(tmp) != NULL)
+					RBE_COLOR(RBE_LEFT(tmp)) = RB_BLACK;
+
+				rbe_rotate_right(t, rbt, parent);
+				rbe = RBH_ROOT(rbt);
+				break;
+			}
+		}
+	}
+
+	if (rbe != NULL)
+		RBE_COLOR(rbe) = RB_BLACK;
+}
+
+static inline struct rb_entry *
+rbe_remove(const struct rb_type *t, struct rb_tree *rbt, struct rb_entry *rbe)
+{
+	struct rb_entry *child, *parent, *old = rbe;
+	unsigned int color;
+
+	if (RBE_LEFT(rbe) == NULL)
+		child = RBE_RIGHT(rbe);
+	else if (RBE_RIGHT(rbe) == NULL)
+		child = RBE_LEFT(rbe);
+	else {
+		struct rb_entry *tmp;
+
+		rbe = RBE_RIGHT(rbe);
+		while ((tmp = RBE_LEFT(rbe)) != NULL)
+			rbe = tmp;
+
+		child = RBE_RIGHT(rbe);
+		parent = RBE_PARENT(rbe);
+		color = RBE_COLOR(rbe);
+		if (child != NULL)
+			RBE_PARENT(child) = parent;
+		if (parent != NULL) {
+			if (RBE_LEFT(parent) == rbe)
+				RBE_LEFT(parent) = child;
+			else
+				RBE_RIGHT(parent) = child;
+
+			rbe_if_augment(t, parent);
+		} else
+			RBH_ROOT(rbt) = child;
+		if (RBE_PARENT(rbe) == old)
+			parent = rbe;
+		*rbe = *old;
+
+		tmp = RBE_PARENT(old);
+		if (tmp != NULL) {
+			if (RBE_LEFT(tmp) == old)
+				RBE_LEFT(tmp) = rbe;
+			else
+				RBE_RIGHT(tmp) = rbe;
+
+			rbe_if_augment(t, tmp);
+		} else
+			RBH_ROOT(rbt) = rbe;
+
+		RBE_PARENT(RBE_LEFT(old)) = rbe;
+		if (RBE_RIGHT(old))
+			RBE_PARENT(RBE_RIGHT(old)) = rbe;
+
+		if (t->t_augment != NULL && parent != NULL) {
+			tmp = parent;
+			do {
+				rbe_augment(t, tmp);
+				tmp = RBE_PARENT(tmp);
+			} while (tmp != NULL);
+		}
+
+		goto color;
+	}
+
+	parent = RBE_PARENT(rbe);
+	color = RBE_COLOR(rbe);
+
+	if (child != NULL)
+		RBE_PARENT(child) = parent;
+	if (parent != NULL) {
+		if (RBE_LEFT(parent) == rbe)
+			RBE_LEFT(parent) = child;
+		else
+			RBE_RIGHT(parent) = child;
+
+		rbe_if_augment(t, parent);
+	} else
+		RBH_ROOT(rbt) = child;
+color:
+	if (color == RB_BLACK)
+		rbe_remove_color(t, rbt, parent, child);
+
+	return (old);
+}
+
+void *
+_rb_remove(const struct rb_type *t, struct rb_tree *rbt, void *elm)
+{
+	struct rb_entry *rbe = rb_n2e(t, elm);
+	struct rb_entry *old;
+
+	old = rbe_remove(t, rbt, rbe);
+
+	return (old == NULL ? NULL : rb_e2n(t, old));
+}
+
+void *
+_rb_insert(const struct rb_type *t, struct rb_tree *rbt, void *elm)
+{
+	struct rb_entry *rbe = rb_n2e(t, elm);
+	struct rb_entry *tmp;
+	struct rb_entry *parent = NULL;
+	void *node;
+	int comp = 0;
+
+	tmp = RBH_ROOT(rbt);
+	while (tmp != NULL) {
+		parent = tmp;
+
+		node = rb_e2n(t, tmp);
+		comp = (*t->t_compare)(elm, node);
+		if (comp < 0)
+			tmp = RBE_LEFT(tmp);
+		else if (comp > 0)
+			tmp = RBE_RIGHT(tmp);
+		else
+			return (node);
+	}
+
+	rbe_set(rbe, parent);
+
+	if (parent != NULL) {
+		if (comp < 0)
+			RBE_LEFT(parent) = rbe;
+		else
+			RBE_RIGHT(parent) = rbe;
+
+		rbe_if_augment(t, parent);
+	} else
+		RBH_ROOT(rbt) = rbe;
+
+	rbe_insert_color(t, rbt, rbe);
+
+	return (NULL);
+}
+
+/* Finds the node with the same key as elm */
+void *
+_rb_find(const struct rb_type *t, struct rb_tree *rbt, const void *key)
+{
+	struct rb_entry *tmp = RBH_ROOT(rbt);
+	void *node;
+	int comp;
+
+	while (tmp != NULL) {
+		node = rb_e2n(t, tmp);
+		comp = (*t->t_compare)(key, node);
+		if (comp < 0)
+			tmp = RBE_LEFT(tmp);
+		else if (comp > 0)
+			tmp = RBE_RIGHT(tmp);
+		else
+			return (node);
+	}
+
+	return (NULL);
+}
+
+/* Finds the first node greater than or equal to the search key */
+void *
+_rb_nfind(const struct rb_type *t, struct rb_tree *rbt, const void *key)
+{
+	struct rb_entry *tmp = RBH_ROOT(rbt);
+	void *node;
+	void *res = NULL;
+	int comp;
+
+	while (tmp != NULL) {
+		node = rb_e2n(t, tmp);
+		comp = (*t->t_compare)(key, node);
+		if (comp < 0) {
+			res = node;
+			tmp = RBE_LEFT(tmp);
+		} else if (comp > 0)
+			tmp = RBE_RIGHT(tmp);
+		else
+			return (node);
+	}
+
+	return (res);
+}
+
+void *
+_rb_next(const struct rb_type *t, void *elm)
+{
+	struct rb_entry *rbe = rb_n2e(t, elm);
+
+	if (RBE_RIGHT(rbe) != NULL) {
+		rbe = RBE_RIGHT(rbe);
+		while (RBE_LEFT(rbe) != NULL)
+			rbe = RBE_LEFT(rbe);
+	} else {
+		if (RBE_PARENT(rbe) &&
+		    (rbe == RBE_LEFT(RBE_PARENT(rbe))))
+			rbe = RBE_PARENT(rbe);
+		else {
+			while (RBE_PARENT(rbe) &&
+			    (rbe == RBE_RIGHT(RBE_PARENT(rbe))))
+				rbe = RBE_PARENT(rbe);
+			rbe = RBE_PARENT(rbe);
+		}
+	}
+
+	return (rbe == NULL ? NULL : rb_e2n(t, rbe));
+}
+
+void *
+_rb_prev(const struct rb_type *t, void *elm)
+{
+	struct rb_entry *rbe = rb_n2e(t, elm);
+
+	if (RBE_LEFT(rbe)) {
+		rbe = RBE_LEFT(rbe);
+		while (RBE_RIGHT(rbe))
+			rbe = RBE_RIGHT(rbe);
+	} else {
+		if (RBE_PARENT(rbe) &&
+		    (rbe == RBE_RIGHT(RBE_PARENT(rbe))))
+			rbe = RBE_PARENT(rbe);
+		else {
+			while (RBE_PARENT(rbe) &&
+			    (rbe == RBE_LEFT(RBE_PARENT(rbe))))
+				rbe = RBE_PARENT(rbe);
+			rbe = RBE_PARENT(rbe);
+		}
+	}
+
+	return (rbe == NULL ? NULL : rb_e2n(t, rbe));
+}
+
+void *
+_rb_root(const struct rb_type *t, struct rb_tree *rbt)
+{
+	struct rb_entry *rbe = RBH_ROOT(rbt);
+
+	return (rbe == NULL ? rbe : rb_e2n(t, rbe));
+}
+
+void *
+_rb_min(const struct rb_type *t, struct rb_tree *rbt)
+{
+	struct rb_entry *rbe = RBH_ROOT(rbt);
+	struct rb_entry *parent = NULL;
+
+	while (rbe != NULL) {
+		parent = rbe;
+		rbe = RBE_LEFT(rbe);
+	}
+
+	return (parent == NULL ? NULL : rb_e2n(t, parent));
+}
+
+void *
+_rb_max(const struct rb_type *t, struct rb_tree *rbt)
+{
+	struct rb_entry *rbe = RBH_ROOT(rbt);
+	struct rb_entry *parent = NULL;
+
+	while (rbe != NULL) {
+		parent = rbe;
+		rbe = RBE_RIGHT(rbe);
+	}
+
+	return (parent == NULL ? NULL : rb_e2n(t, parent));
+}
+
+void *
+_rb_left(const struct rb_type *t, void *node)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+	rbe = RBE_LEFT(rbe);
+	return (rbe == NULL ? NULL : rb_e2n(t, rbe));
+}
+
+void *
+_rb_right(const struct rb_type *t, void *node)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+	rbe = RBE_RIGHT(rbe);
+	return (rbe == NULL ? NULL : rb_e2n(t, rbe));
+}
+
+void *
+_rb_parent(const struct rb_type *t, void *node)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+	rbe = RBE_PARENT(rbe);
+	return (rbe == NULL ? NULL : rb_e2n(t, rbe));
+}
+
+void
+_rb_set_left(const struct rb_type *t, void *node, void *left)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+	struct rb_entry *rbl = (left == NULL) ? NULL : rb_n2e(t, left);
+
+	RBE_LEFT(rbe) = rbl;
+}
+
+void
+_rb_set_right(const struct rb_type *t, void *node, void *right)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+	struct rb_entry *rbr = (right == NULL) ? NULL : rb_n2e(t, right);
+
+	RBE_RIGHT(rbe) = rbr;
+}
+
+void
+_rb_set_parent(const struct rb_type *t, void *node, void *parent)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+	struct rb_entry *rbp = (parent == NULL) ? NULL : rb_n2e(t, parent);
+
+	RBE_PARENT(rbe) = rbp;
+}
+
+void
+_rb_poison(const struct rb_type *t, void *node, unsigned long poison)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+
+	RBE_PARENT(rbe) = RBE_LEFT(rbe) = RBE_RIGHT(rbe) =
+	    (struct rb_entry *)poison;
+}
+
+int
+_rb_check(const struct rb_type *t, void *node, unsigned long poison)
+{
+	struct rb_entry *rbe = rb_n2e(t, node);
+
+	return ((unsigned long)RBE_PARENT(rbe) == poison &&
+	    (unsigned long)RBE_LEFT(rbe) == poison &&
+	    (unsigned long)RBE_RIGHT(rbe) == poison);
+}