vm_radix.h revision 226876 
1/*
2 * Copyright (c) 2008 Mayur Shardul <mayur.shardul@gmail.com>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 */
27
28#ifndef _VM_RADIX_H_
29#define _VM_RADIX_H_
30
31#include <sys/queue.h>
32
33/* Default values of the tree parameters */
34#define	VM_RADIX_WIDTH	5
35#define	VM_RADIX_COUNT	(1 << VM_RADIX_WIDTH)
36#define	VM_RADIX_MASK	(VM_RADIX_COUNT - 1)
37#define	VM_RADIX_LIMIT	howmany((sizeof(vm_pindex_t) * NBBY), VM_RADIX_WIDTH)
38#define	VM_RADIX_HEIGHT	0xf		/* Bits of height in root */
39
40CTASSERT(VM_RADIX_HEIGHT >= VM_RADIX_LIMIT);
41
42/* Calculates maximum value for a tree of height h. */
43#define	VM_RADIX_MAX(h)							\
44	    ((h) == VM_RADIX_LIMIT ? ((vm_pindex_t)-1) :		\
45	    (((vm_pindex_t)1 << ((h) * VM_RADIX_WIDTH)) - 1))
46
47struct vm_radix_node {
48	void 		*rn_child[VM_RADIX_COUNT];	/* child nodes. */
49    	uint16_t	rn_count;			/* Valid children. */
50};
51
52/*
53 * Radix tree root.  The height and pointer are set together to permit
54 * coherent lookups while the root is modified.
55 */
56struct vm_radix {
57	uintptr_t	rt_root;		/* root + height */
58};
59
60void	vm_radix_init(void);
61int 	vm_radix_insert(struct vm_radix *, vm_pindex_t, void *);
62void	*vm_radix_remove(struct vm_radix *, vm_pindex_t);
63void	*vm_radix_lookup(struct vm_radix *, vm_pindex_t);
64int	vm_radix_lookupn(struct vm_radix *rtree, vm_pindex_t start,
65	    vm_pindex_t end, void **out, int cnt, vm_pindex_t *next);
66void	*vm_radix_lookup_le(struct vm_radix *, vm_pindex_t);
67void 	vm_radix_shrink(struct vm_radix *);
68
69/*
70 * Look up any entry at a position greater or equal to index.
71 */
72static inline void *
73vm_radix_lookup_ge(struct vm_radix *rtree, vm_pindex_t index)
74{
75        vm_pindex_t unused;
76        void *val;
77
78        if (vm_radix_lookupn(rtree, index, 0, &val, 1, &unused))
79                return (val);
80        return (NULL);
81}
82
83#endif /* !_VM_RADIX_H_ */
84