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Length: 2091 (0x82b)
Types: TextFile
Names: »hash.c«
└─⟦a05ed705a⟧ Bits:30007078 DKUUG GNU 2/12/89
└─⟦847972ed9⟧ »./gdbm0.9.tar.Z«
└─⟦e41d67701⟧
└─⟦this⟧ »gdbm/hash.c«
/* hash.c - The gdbm hash function. */
/* GNU DBM - DataBase Manager (database subroutines) by Philip A. Nelson
Copyright (C) 1989 Free Software Foundation, Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
You may contact the author by:
e-mail: phil@wwu.edu
us-mail: Philip A. Nelson
Computer Science Department
Western Washington University
Bellingham, WA 98226
phone: (206) 676-3035
*************************************************************************/
#include <stdio.h>
#include <sys/types.h>
#include <sys/file.h>
#include <sys/stat.h>
#include "gdbmdefs.h"
/* This hash function computes a 31 bit value. The value is used to index
the hash directory using the top n bits. It is also used in a hash bucket
to find the home position of the element by taking the value modulo the
bucket hash table size. */
int
_gdbm_hash (key)
datum key;
{
int value; /* Used to compute the hash value. */
char *old_state; /* Remember the old random state. */
int index; /* Used to cycle through random values. */
/* Set the initial value from key. */
value = 0x238F13AF * key.dsize;
for (index = 0; index < key.dsize; index++)
value = (value + (key.dptr[index] << (index*5 % 24))) & 0x7FFFFFFF;
/* value = ( 0x437EDA5D * value + 0x7378E374 ) & 0x7FFFFFFF; /* TEST? */
value = ( 1103515243 * value + 12345 ) & 0x7FFFFFFF;
/* Return the value. */
return value;
}