1 | /* $NetBSD: subr_hash.c,v 1.7 2016/07/06 05:20:48 ozaki-r Exp $ */ |
2 | |
3 | /* |
4 | * Copyright (c) 1982, 1986, 1991, 1993 |
5 | * The Regents of the University of California. All rights reserved. |
6 | * (c) UNIX System Laboratories, Inc. |
7 | * All or some portions of this file are derived from material licensed |
8 | * to the University of California by American Telephone and Telegraph |
9 | * Co. or Unix System Laboratories, Inc. and are reproduced herein with |
10 | * the permission of UNIX System Laboratories, Inc. |
11 | * |
12 | * Redistribution and use in source and binary forms, with or without |
13 | * modification, are permitted provided that the following conditions |
14 | * are met: |
15 | * 1. Redistributions of source code must retain the above copyright |
16 | * notice, this list of conditions and the following disclaimer. |
17 | * 2. Redistributions in binary form must reproduce the above copyright |
18 | * notice, this list of conditions and the following disclaimer in the |
19 | * documentation and/or other materials provided with the distribution. |
20 | * 3. Neither the name of the University nor the names of its contributors |
21 | * may be used to endorse or promote products derived from this software |
22 | * without specific prior written permission. |
23 | * |
24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
34 | * SUCH DAMAGE. |
35 | * |
36 | * @(#)kern_subr.c 8.4 (Berkeley) 2/14/95 |
37 | */ |
38 | |
39 | #include <sys/cdefs.h> |
40 | __KERNEL_RCSID(0, "$NetBSD: subr_hash.c,v 1.7 2016/07/06 05:20:48 ozaki-r Exp $" ); |
41 | |
42 | #include <sys/param.h> |
43 | #include <sys/bitops.h> |
44 | #include <sys/kmem.h> |
45 | #include <sys/systm.h> |
46 | #include <sys/pslist.h> |
47 | |
48 | static size_t |
49 | hash_list_size(enum hashtype htype) |
50 | { |
51 | LIST_HEAD(, generic) *hashtbl_list; |
52 | SLIST_HEAD(, generic) *hashtbl_slist; |
53 | TAILQ_HEAD(, generic) *hashtbl_tailq; |
54 | struct pslist_head *hashtbl_pslist; |
55 | size_t esize; |
56 | |
57 | switch (htype) { |
58 | case HASH_LIST: |
59 | esize = sizeof(*hashtbl_list); |
60 | break; |
61 | case HASH_PSLIST: |
62 | esize = sizeof(*hashtbl_pslist); |
63 | break; |
64 | case HASH_SLIST: |
65 | esize = sizeof(*hashtbl_slist); |
66 | break; |
67 | case HASH_TAILQ: |
68 | esize = sizeof(*hashtbl_tailq); |
69 | break; |
70 | default: |
71 | panic("hashdone: invalid table type" ); |
72 | } |
73 | return esize; |
74 | } |
75 | |
76 | /* |
77 | * General routine to allocate a hash table. |
78 | * Allocate enough memory to hold at least `elements' list-head pointers. |
79 | * Return a pointer to the allocated space and set *hashmask to a pattern |
80 | * suitable for masking a value to use as an index into the returned array. |
81 | */ |
82 | void * |
83 | hashinit(u_int elements, enum hashtype htype, bool waitok, u_long *hashmask) |
84 | { |
85 | LIST_HEAD(, generic) *hashtbl_list; |
86 | SLIST_HEAD(, generic) *hashtbl_slist; |
87 | TAILQ_HEAD(, generic) *hashtbl_tailq; |
88 | struct pslist_head *hashtbl_pslist; |
89 | u_long hashsize, i; |
90 | size_t esize; |
91 | void *p; |
92 | |
93 | KASSERT(elements > 0); |
94 | |
95 | #define MAXELEMENTS (1U << ((sizeof(elements) * NBBY) - 1)) |
96 | if (elements > MAXELEMENTS) |
97 | elements = MAXELEMENTS; |
98 | |
99 | hashsize = 1UL << (ilog2(elements - 1) + 1); |
100 | esize = hash_list_size(htype); |
101 | |
102 | p = kmem_alloc(hashsize * esize, waitok ? KM_SLEEP : KM_NOSLEEP); |
103 | if (p == NULL) |
104 | return NULL; |
105 | |
106 | switch (htype) { |
107 | case HASH_LIST: |
108 | hashtbl_list = p; |
109 | for (i = 0; i < hashsize; i++) |
110 | LIST_INIT(&hashtbl_list[i]); |
111 | break; |
112 | case HASH_PSLIST: |
113 | hashtbl_pslist = p; |
114 | for (i = 0; i < hashsize; i++) |
115 | PSLIST_INIT(&hashtbl_pslist[i]); |
116 | break; |
117 | case HASH_SLIST: |
118 | hashtbl_slist = p; |
119 | for (i = 0; i < hashsize; i++) |
120 | SLIST_INIT(&hashtbl_slist[i]); |
121 | break; |
122 | case HASH_TAILQ: |
123 | hashtbl_tailq = p; |
124 | for (i = 0; i < hashsize; i++) |
125 | TAILQ_INIT(&hashtbl_tailq[i]); |
126 | break; |
127 | } |
128 | *hashmask = hashsize - 1; |
129 | return p; |
130 | } |
131 | |
132 | /* |
133 | * Free memory from hash table previosly allocated via hashinit(). |
134 | */ |
135 | void |
136 | hashdone(void *hashtbl, enum hashtype htype, u_long hashmask) |
137 | { |
138 | const size_t esize = hash_list_size(htype); |
139 | kmem_free(hashtbl, esize * (hashmask + 1)); |
140 | } |
141 | |