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      1 /*	$NetBSD: hash-string.h,v 1.1.1.1 2016/01/14 00:11:27 christos Exp $	*/
      2 
      3 /* Description of GNU message catalog format: string hashing function.
      4    Copyright (C) 1995, 1997-1998, 2000-2003 Free Software Foundation, Inc.
      5 
      6    This program is free software; you can redistribute it and/or modify it
      7    under the terms of the GNU Library General Public License as published
      8    by the Free Software Foundation; either version 2, or (at your option)
      9    any later version.
     10 
     11    This program is distributed in the hope that it will be useful,
     12    but WITHOUT ANY WARRANTY; without even the implied warranty of
     13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     14    Library General Public License for more details.
     15 
     16    You should have received a copy of the GNU Library General Public
     17    License along with this program; if not, write to the Free Software
     18    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
     19    USA.  */
     20 
     21 /* @@ end of prolog @@ */
     22 
     23 /* We assume to have `unsigned long int' value with at least 32 bits.  */
     24 #define HASHWORDBITS 32
     25 
     26 
     27 /* Defines the so called `hashpjw' function by P.J. Weinberger
     28    [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
     29    1986, 1987 Bell Telephone Laboratories, Inc.]  */
     30 static inline unsigned long int
     31 hash_string (const char *str_param)
     32 {
     33   unsigned long int hval, g;
     34   const char *str = str_param;
     35 
     36   /* Compute the hash value for the given string.  */
     37   hval = 0;
     38   while (*str != '\0')
     39     {
     40       hval <<= 4;
     41       hval += (unsigned char) *str++;
     42       g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4));
     43       if (g != 0)
     44 	{
     45 	  hval ^= g >> (HASHWORDBITS - 8);
     46 	  hval ^= g;
     47 	}
     48     }
     49   return hval;
     50 }
     51