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subr_hash.c revision 1.1 
      1 /*	$NetBSD: subr_hash.c,v 1.1 2007/07/28 12:53:52 pooka 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 1.1 2007/07/28 12:53:52 pooka 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 	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_TAILQ:
     72 		esize = sizeof(*hashtbl_tailq);
     73 		break;
     74 	default:
     75 #ifdef DIAGNOSTIC
     76 		panic("hashinit: invalid table type");
     77 #else
     78 		return NULL;
     79 #endif
     80 	}
     81 
     82 	if ((p = malloc(hashsize * esize, mtype, mflags)) == 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_TAILQ:
     92 		hashtbl_tailq = p;
     93 		for (i = 0; i < hashsize; i++)
     94 			TAILQ_INIT(&hashtbl_tailq[i]);
     95 		break;
     96 	}
     97 	*hashmask = hashsize - 1;
     98 	return (p);
     99 }
    100 
    101 /*
    102  * Free memory from hash table previosly allocated via hashinit().
    103  */
    104 void
    105 hashdone(void *hashtbl, struct malloc_type *mtype)
    106 {
    107 
    108 	free(hashtbl, mtype);
    109 }
    110