1 /* $NetBSD: subr_hash.c,v 1.2 2008/03/17 21:16:03 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 1.2 2008/03/17 21:16:03 rmind Exp $"); 41 42 #include <sys/param.h> 43 #include <sys/malloc.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, struct malloc_type *mtype, 54 int mflags, u_long *hashmask) 55 { 56 u_long hashsize, i; 57 LIST_HEAD(, generic) *hashtbl_list; 58 SLIST_HEAD(, generic) *hashtbl_slist; 59 TAILQ_HEAD(, generic) *hashtbl_tailq; 60 size_t esize; 61 void *p; 62 63 if (elements == 0) 64 panic("hashinit: bad cnt"); 65 for (hashsize = 1; hashsize < elements; hashsize <<= 1) 66 continue; 67 68 switch (htype) { 69 case HASH_LIST: 70 esize = sizeof(*hashtbl_list); 71 break; 72 case HASH_SLIST: 73 esize = sizeof(*hashtbl_slist); 74 break; 75 case HASH_TAILQ: 76 esize = sizeof(*hashtbl_tailq); 77 break; 78 default: 79 #ifdef DIAGNOSTIC 80 panic("hashinit: invalid table type"); 81 #else 82 return NULL; 83 #endif 84 } 85 86 if ((p = malloc(hashsize * esize, mtype, mflags)) == NULL) 87 return (NULL); 88 89 switch (htype) { 90 case HASH_LIST: 91 hashtbl_list = p; 92 for (i = 0; i < hashsize; i++) 93 LIST_INIT(&hashtbl_list[i]); 94 break; 95 case HASH_SLIST: 96 hashtbl_slist = p; 97 for (i = 0; i < hashsize; i++) 98 SLIST_INIT(&hashtbl_slist[i]); 99 break; 100 case HASH_TAILQ: 101 hashtbl_tailq = p; 102 for (i = 0; i < hashsize; i++) 103 TAILQ_INIT(&hashtbl_tailq[i]); 104 break; 105 } 106 *hashmask = hashsize - 1; 107 return (p); 108 } 109 110 /* 111 * Free memory from hash table previosly allocated via hashinit(). 112 */ 113 void 114 hashdone(void *hashtbl, struct malloc_type *mtype) 115 { 116 117 free(hashtbl, mtype); 118 } 119