1 /* $NetBSD: subr_hash.c,v 1.6 2014/05/29 21:15:55 rmind 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 1.6 2014/05/29 21:15:55 rmind Exp $"); 41 42 #include <sys/param.h> 43 #include <sys/bitops.h> 44 #include <sys/kmem.h> 45 #include <sys/systm.h> 46 47 static size_t 48 hash_list_size(enum hashtype htype) 49 { 50 LIST_HEAD(, generic) *hashtbl_list; 51 SLIST_HEAD(, generic) *hashtbl_slist; 52 TAILQ_HEAD(, generic) *hashtbl_tailq; 53 size_t esize; 54 55 switch (htype) { 56 case HASH_LIST: 57 esize = sizeof(*hashtbl_list); 58 break; 59 case HASH_SLIST: 60 esize = sizeof(*hashtbl_slist); 61 break; 62 case HASH_TAILQ: 63 esize = sizeof(*hashtbl_tailq); 64 break; 65 default: 66 panic("hashdone: invalid table type"); 67 } 68 return esize; 69 } 70 71 /* 72 * General routine to allocate a hash table. 73 * Allocate enough memory to hold at least `elements' list-head pointers. 74 * Return a pointer to the allocated space and set *hashmask to a pattern 75 * suitable for masking a value to use as an index into the returned array. 76 */ 77 void * 78 hashinit(u_int elements, enum hashtype htype, bool waitok, u_long *hashmask) 79 { 80 LIST_HEAD(, generic) *hashtbl_list; 81 SLIST_HEAD(, generic) *hashtbl_slist; 82 TAILQ_HEAD(, generic) *hashtbl_tailq; 83 u_long hashsize, i; 84 size_t esize; 85 void *p; 86 87 KASSERT(elements > 0); 88 89 #define MAXELEMENTS (1U << ((sizeof(elements) * NBBY) - 1)) 90 if (elements > MAXELEMENTS) 91 elements = MAXELEMENTS; 92 93 hashsize = 1UL << (ilog2(elements - 1) + 1); 94 esize = hash_list_size(htype); 95 96 p = kmem_alloc(hashsize * esize, waitok ? KM_SLEEP : KM_NOSLEEP); 97 if (p == NULL) 98 return NULL; 99 100 switch (htype) { 101 case HASH_LIST: 102 hashtbl_list = p; 103 for (i = 0; i < hashsize; i++) 104 LIST_INIT(&hashtbl_list[i]); 105 break; 106 case HASH_SLIST: 107 hashtbl_slist = p; 108 for (i = 0; i < hashsize; i++) 109 SLIST_INIT(&hashtbl_slist[i]); 110 break; 111 case HASH_TAILQ: 112 hashtbl_tailq = p; 113 for (i = 0; i < hashsize; i++) 114 TAILQ_INIT(&hashtbl_tailq[i]); 115 break; 116 } 117 *hashmask = hashsize - 1; 118 return p; 119 } 120 121 /* 122 * Free memory from hash table previosly allocated via hashinit(). 123 */ 124 void 125 hashdone(void *hashtbl, enum hashtype htype, u_long hashmask) 126 { 127 const size_t esize = hash_list_size(htype); 128 kmem_free(hashtbl, esize * (hashmask + 1)); 129 } 130