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hashpart.h

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*                  Copyright (c) 1985-2006 AT&T Corp.                  *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                            by AT&T Corp.                             *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#pragma prototyped
/*
 * K. P. Vo
 * G. S. Fowler
 * AT&T Research
 *
 * ``the best'' combined linear congruent checksum/hash/PRNG
 */

#ifndef _HASHPART_H
#define _HASHPART_H

#define HASH_ADD(h)     (0x9c39c33dL)

#if __sparc__ || __sparc || sparc

#define HASH_A(h,n)     ((((h) << 2) - (h)) << (n))
#define HASH_B(h,n)     ((((h) << 4) - (h)) << (n))
#define HASH_C(h,n)     ((HASH_A(h,7) + HASH_B(h,0)) << (n))
#define HASH_MPY(h)     (HASH_C(h,22)+HASH_C(h,10)+HASH_A(h,6)+HASH_A(h,3)+(h))

#else

#define HASH_MPY(h)     ((h)*0x63c63cd9L)

#endif

#define HASHPART(h,c)   (h = HASH_MPY(h) + HASH_ADD(h) + (c))

#endif

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