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lrzsz ver 0.12.20

    1: /* Implements a string hashing function.
    2:    Copyright (C) 1995, 1997 Free Software Foundation, Inc.
    3: 
    4:    This program is free software; you can redistribute it and/or modify
    5:    it under the terms of the GNU General Public License as published by
    6:    the Free Software Foundation; either version 2, or (at your option)
    7:    any later version.
    8: 
    9:    This program is distributed in the hope that it will be useful,
   10:    but WITHOUT ANY WARRANTY; without even the implied warranty of
   11:    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   12:    GNU General Public License for more details.
   13: 
   14:    You should have received a copy of the GNU Library General Public
   15:    License along with the GNU C Library; see the file COPYING.LIB.  If not,
   16:    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   17:    Boston, MA 02111-1307, USA.  */
   18: 
   19: #ifdef HAVE_VALUES_H
   20: # include <values.h>
   21: #endif
   22: 
   23: /* @@ end of prolog @@ */
   24: 
   25: #ifndef PARAMS
   26: # if __STDC__
   27: #  define PARAMS(Args) Args
   28: # else
   29: #  define PARAMS(Args) ()
   30: # endif
   31: #endif
   32: 
   33: /* We assume to have `unsigned long int' value with at least 32 bits.  */
   34: #define HASHWORDBITS 32
   35: 
   36: 
   37: /* Defines the so called `hashpjw' function by P.J. Weinberger
   38:    [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
   39:    1986, 1987 Bell Telephone Laboratories, Inc.]  */
   40: static unsigned long hash_string PARAMS ((const char *__str_param));
   41: 
   42: static inline unsigned long
   43: hash_string (str_param)
   44:      const char *str_param;
   45: {
   46:   unsigned long int hval, g;
   47:   const char *str = str_param;
   48: 
   49:   /* Compute the hash value for the given string.  */
   50:   hval = 0;
   51:   while (*str != '\0')
   52:     {
   53:       hval <<= 4;
   54:       hval += (unsigned long) *str++;
   55:       g = hval & ((unsigned long) 0xf << (HASHWORDBITS - 4));
   56:       if (g != 0)
   57: 	{
   58: 	  hval ^= g >> (HASHWORDBITS - 8);
   59: 	  hval ^= g;
   60: 	}
   61:     }
   62:   return hval;
   63: }