1 /* $NetBSD: subr_hash.c,v 1.3 2008/05/05 17:11:17 ad 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 1.3 2008/05/05 17:11:17 ad Exp $"); 41 42 #include <sys/param.h> 43 #include <sys/kmem.h> 44 #include <sys/systm.h> 45 46 /* 47 * General routine to allocate a hash table. 48 * Allocate enough memory to hold at least `elements' list-head pointers. 49 * Return a pointer to the allocated space and set *hashmask to a pattern 50 * suitable for masking a value to use as an index into the returned array. 51 */ 52 void * 53 hashinit(u_int elements, enum hashtype htype, bool waitok, u_long *hashmask) 54 { 55 u_long hashsize, i; 56 LIST_HEAD(, generic) *hashtbl_list; 57 SLIST_HEAD(, generic) *hashtbl_slist; 58 TAILQ_HEAD(, generic) *hashtbl_tailq; 59 size_t esize; 60 void *p; 61 62 if (elements == 0) 63 panic("hashinit: bad cnt"); 64 for (hashsize = 1; hashsize < elements; hashsize <<= 1) 65 continue; 66 67 switch (htype) { 68 case HASH_LIST: 69 esize = sizeof(*hashtbl_list); 70 break; 71 case HASH_SLIST: 72 esize = sizeof(*hashtbl_slist); 73 break; 74 case HASH_TAILQ: 75 esize = sizeof(*hashtbl_tailq); 76 break; 77 default: 78 panic("hashinit: invalid table type"); 79 } 80 81 p = kmem_alloc(hashsize * esize, (waitok ? KM_SLEEP : KM_NOSLEEP)); 82 if (p == NULL) 83 return (NULL); 84 85 switch (htype) { 86 case HASH_LIST: 87 hashtbl_list = p; 88 for (i = 0; i < hashsize; i++) 89 LIST_INIT(&hashtbl_list[i]); 90 break; 91 case HASH_SLIST: 92 hashtbl_slist = p; 93 for (i = 0; i < hashsize; i++) 94 SLIST_INIT(&hashtbl_slist[i]); 95 break; 96 case HASH_TAILQ: 97 hashtbl_tailq = p; 98 for (i = 0; i < hashsize; i++) 99 TAILQ_INIT(&hashtbl_tailq[i]); 100 break; 101 } 102 *hashmask = hashsize - 1; 103 return (p); 104 } 105 106 /* 107 * Free memory from hash table previosly allocated via hashinit(). 108 */ 109 void 110 hashdone(void *hashtbl, enum hashtype htype, u_long hashmask) 111 { 112 LIST_HEAD(, generic) *hashtbl_list; 113 SLIST_HEAD(, generic) *hashtbl_slist; 114 TAILQ_HEAD(, generic) *hashtbl_tailq; 115 size_t esize; 116 117 switch (htype) { 118 case HASH_LIST: 119 esize = sizeof(*hashtbl_list); 120 break; 121 case HASH_SLIST: 122 esize = sizeof(*hashtbl_slist); 123 break; 124 case HASH_TAILQ: 125 esize = sizeof(*hashtbl_tailq); 126 break; 127 default: 128 panic("hashdone: invalid table type"); 129 } 130 131 kmem_free(hashtbl, esize * (hashmask + 1)); 132 } 133