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/* Implements a string hashing function.

   Copyright (C) 1995, 1997 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; either version 2, or (at your option)

   any later version.

   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 Library General Public

   License along with the GNU C Library; see the file COPYING.LIB.  If not,

   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,

   Boston, MA 02111-1307, USA.  */

/* @@ end of prolog @@ */

#ifndef PARAMS

# if __STDC__

#  define PARAMS(Args) Args

# else

#  define PARAMS(Args) ()

# endif

#endif

/* We assume to have `unsigned long int' value with at least 32 bits.  */

#define HASHWORDBITS 32

/* Defines the so called `hashpjw' function by P.J. Weinberger

   [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,

   1986, 1987 Bell Telephone Laboratories, Inc.]  */

static unsigned long hash_string PARAMS ((const char *__str_param));

static inline unsigned long

hash_string (str_param)

     const char *str_param;

{

  unsigned long int hval, g;

  const char *str = str_param;

  /* Compute the hash value for the given string.  */

  hval = 0;

  while (*str != '\0')

    {

      hval <<= 4;

      hval += (unsigned long) *str++;

      g = hval & ((unsigned long) 0xf << (HASHWORDBITS - 4));

      if (g != 0)

        {

          hval ^= g >> (HASHWORDBITS - 8);

          hval ^= g;

        }

    }

  return hval;

}