usr/src/lib/libast/common/include/hashpart.h

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #pragma prototyped
  23 /*
  24  * K. P. Vo
  25  * G. S. Fowler
  26  * AT&T Research
  27  *
  28  * ``the best'' combined linear congruent checksum/hash/PRNG
  29  */
  30
  31 #ifndef _HASHPART_H
  32 #define _HASHPART_H
  33
  34 #define HASH_ADD(h)     (0x9c39c33dL)
  35
  36 #if __sparc__ || __sparc || sparc
  37
  38 #define HASH_A(h,n)     ((((h) << 2) - (h)) << (n))
  39 #define HASH_B(h,n)     ((((h) << 4) - (h)) << (n))
  40 #define HASH_C(h,n)     ((HASH_A(h,7) + HASH_B(h,0)) << (n))
  41 #define HASH_MPY(h)     (HASH_C(h,22)+HASH_C(h,10)+HASH_A(h,6)+HASH_A(h,3)+(h))
  42
  43 #else
  44
  45 #define HASH_MPY(h)     ((h)*0x63c63cd9L)
  46
  47 #endif
  48
  49 #define HASHPART(h,c)   (h = HASH_MPY(h) + HASH_ADD(h) + (c))
  50
  51 #endif