Home | History | Annotate | Line # | Download | only in kern
subr_hash.c revision 1.3 
      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