minix/include/sys/hash.h

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2011-02-21 14:13:55 +01:00
/* $NetBSD: hash.h,v 1.6 2008/04/28 20:24:10 martin Exp $ */
/*-
* Copyright (c) 2001 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Luke Mewburn.
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
#ifndef _SYS_HASH_H_
#define _SYS_HASH_H_
#include <sys/types.h>
#ifdef __HAVE_MACHINE_HASH_H
#include <machine/hash.h>
#endif
#ifndef __HAVE_HASH32_BUF /* not overridden by MD hash */
#define HASH32_BUF_INIT 5381
/*
* uint32_t
* hash32_buf(const void *bf, size_t len, uint32_t hash)
* return a 32 bit hash of the binary buffer buf (size len),
* seeded with an initial hash value of hash (usually HASH32_BUF_INIT).
*/
static __inline uint32_t
hash32_buf(const void *bf, size_t len, uint32_t hash)
{
const uint8_t *s = bf;
while (len-- != 0) /* "nemesi": k=257, r=r*257 */
hash = hash * 257 + *s++;
return (hash * 257);
}
#endif /* __HAVE_HASH32_BUF */
#ifndef __HAVE_HASH32_STR /* not overridden by MD hash */
#define HASH32_STR_INIT 5381
/*
* uint32_t
* hash32_str(const void *bf, uint32_t hash)
* return a 32 bit hash of NUL terminated ASCII string buf,
* seeded with an initial hash value of hash (usually HASH32_STR_INIT).
*/
static __inline uint32_t
hash32_str(const void *bf, uint32_t hash)
{
const uint8_t *s = bf;
uint8_t c;
while ((c = *s++) != 0)
hash = hash * 33 + c; /* "perl": k=33, r=r+r/32 */
return (hash + (hash >> 5));
}
/*
* uint32_t
* hash32_strn(const void *bf, size_t len, uint32_t hash)
* return a 32 bit hash of NUL terminated ASCII string buf up to
* a maximum of len bytes,
* seeded with an initial hash value of hash (usually HASH32_STR_INIT).
*/
static __inline uint32_t
hash32_strn(const void *bf, size_t len, uint32_t hash)
{
const uint8_t *s = bf;
uint8_t c;
while ((c = *s++) != 0 && len-- != 0)
hash = hash * 33 + c; /* "perl": k=33, r=r+r/32 */
return (hash + (hash >> 5));
}
#endif /* __HAVE_HASH32_STR */
#endif /* !_SYS_HASH_H_ */