NetBSD/sys/kern/subr_hash.c

110 lines
3.5 KiB
C

/* $NetBSD: subr_hash.c,v 1.1 2007/07/28 12:53:52 pooka Exp $ */
/*
* Copyright (c) 1982, 1986, 1991, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)kern_subr.c 8.4 (Berkeley) 2/14/95
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: subr_hash.c,v 1.1 2007/07/28 12:53:52 pooka Exp $");
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/systm.h>
/*
* General routine to allocate a hash table.
* Allocate enough memory to hold at least `elements' list-head pointers.
* Return a pointer to the allocated space and set *hashmask to a pattern
* suitable for masking a value to use as an index into the returned array.
*/
void *
hashinit(u_int elements, enum hashtype htype, struct malloc_type *mtype,
int mflags, u_long *hashmask)
{
u_long hashsize, i;
LIST_HEAD(, generic) *hashtbl_list;
TAILQ_HEAD(, generic) *hashtbl_tailq;
size_t esize;
void *p;
if (elements == 0)
panic("hashinit: bad cnt");
for (hashsize = 1; hashsize < elements; hashsize <<= 1)
continue;
switch (htype) {
case HASH_LIST:
esize = sizeof(*hashtbl_list);
break;
case HASH_TAILQ:
esize = sizeof(*hashtbl_tailq);
break;
default:
#ifdef DIAGNOSTIC
panic("hashinit: invalid table type");
#else
return NULL;
#endif
}
if ((p = malloc(hashsize * esize, mtype, mflags)) == NULL)
return (NULL);
switch (htype) {
case HASH_LIST:
hashtbl_list = p;
for (i = 0; i < hashsize; i++)
LIST_INIT(&hashtbl_list[i]);
break;
case HASH_TAILQ:
hashtbl_tailq = p;
for (i = 0; i < hashsize; i++)
TAILQ_INIT(&hashtbl_tailq[i]);
break;
}
*hashmask = hashsize - 1;
return (p);
}
/*
* Free memory from hash table previosly allocated via hashinit().
*/
void
hashdone(void *hashtbl, struct malloc_type *mtype)
{
free(hashtbl, mtype);
}