The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/hash.h

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    1 /*      $NetBSD: hash.h,v 1.1 2001/12/05 06:51:55 lukem Exp $   */
    2 
    3 /*-
    4  * Copyright (c) 2001 The NetBSD Foundation, Inc.
    5  * All rights reserved.
    6  *
    7  * This code is derived from software contributed to The NetBSD Foundation
    8  * by Luke Mewburn.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 3. All advertising materials mentioning features or use of this software
   19  *    must display the following acknowledgement:
   20  *        This product includes software developed by the NetBSD
   21  *        Foundation, Inc. and its contributors.
   22  * 4. Neither the name of The NetBSD Foundation nor the names of its
   23  *    contributors may be used to endorse or promote products derived
   24  *    from this software without specific prior written permission.
   25  *
   26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   36  * POSSIBILITY OF SUCH DAMAGE.
   37  */
   38 
   39 #ifndef _SYS_HASH_H_
   40 #define _SYS_HASH_H_
   41 
   42 #include <sys/types.h>
   43 #ifdef __HAVE_MACHINE_HASH_H
   44 #include <machine/hash.h>
   45 #endif
   46 
   47 
   48 #ifndef __HAVE_HASH32_BUF                       /* not overridden by MD hash */
   49 
   50 #define HASH32_BUF_INIT 5381
   51 
   52 /*
   53  * uint32_t
   54  * hash32_buf(const void *buf, size_t len, uint32_t hash)
   55  *      return a 32 bit hash of the binary buffer buf (size len),
   56  *      seeded with an initial hash value of hash (usually HASH32_BUF_INIT).
   57  */
   58 static __inline uint32_t
   59 hash32_buf(const void *buf, size_t len, uint32_t hash)
   60 {
   61         const uint8_t *s = buf;
   62 
   63         while (len-- != 0)                      /* "nemesi": k=257, r=r*257 */
   64                 hash = hash * 257 + *s++;
   65         return (hash * 257);
   66 }
   67 #endif  /* __HAVE_HASH32_BUF */
   68 
   69 
   70 #ifndef __HAVE_HASH32_STR                       /* not overridden by MD hash */
   71 
   72 #define HASH32_STR_INIT 5381
   73 /*
   74  * uint32_t
   75  * hash32_str(const void *buf, uint32_t hash)
   76  *      return a 32 bit hash of NUL terminated ASCII string buf,
   77  *      seeded with an initial hash value of hash (usually HASH32_STR_INIT).
   78  */
   79 static __inline uint32_t
   80 hash32_str(const void *buf, uint32_t hash)
   81 {
   82         const uint8_t *s = buf;
   83         uint8_t c;
   84 
   85         while ((c = *s++) != 0)
   86                 hash = hash * 33 + c;           /* "perl": k=33, r=r+r/32 */
   87         return (hash + (hash >> 5));
   88 }
   89 
   90 /*
   91  * uint32_t
   92  * hash32_strn(const void *buf, size_t len, uint32_t hash)
   93  *      return a 32 bit hash of NUL terminated ASCII string buf up to
   94  *      a maximum of len bytes,
   95  *      seeded with an initial hash value of hash (usually HASH32_STR_INIT).
   96  */
   97 static __inline uint32_t
   98 hash32_strn(const void *buf, size_t len, uint32_t hash)
   99 {
  100         const uint8_t   *s = buf;
  101         uint8_t c;
  102 
  103         while ((c = *s++) != 0 && len-- != 0)
  104                 hash = hash * 33 + c;           /* "perl": k=33, r=r+r/32 */
  105         return (hash + (hash >> 5));
  106 }
  107 #endif  /* __HAVE_HASH32_STR */
  108 
  109 
  110 #endif  /* !_SYS_HASH_H_ */

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