1/* Description of GNU message catalog format: string hashing function.
2   Copyright (C) 1995, 1997-1998, 2000-2003 Free Software Foundation, Inc.
3
4   This program is free software; you can redistribute it and/or modify it
5   under the terms of the GNU Library General Public License as published
6   by 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 GNU
12   Library General Public License for more details.
13
14   You should have received a copy of the GNU Library General Public
15   License along with this program; if not, write to the Free Software
16   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
17   USA.  */
18
19/* @@ end of prolog @@ */
20
21/* We assume to have `unsigned long int' value with at least 32 bits.  */
22#define HASHWORDBITS 32
23
24
25/* Defines the so called `hashpjw' function by P.J. Weinberger
26   [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
27   1986, 1987 Bell Telephone Laboratories, Inc.]  */
28static inline unsigned long int
29hash_string (const char *str_param)
30{
31  unsigned long int hval, g;
32  const char *str = str_param;
33
34  /* Compute the hash value for the given string.  */
35  hval = 0;
36  while (*str != '\0')
37    {
38      hval <<= 4;
39      hval += (unsigned char) *str++;
40      g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4));
41      if (g != 0)
42	{
43	  hval ^= g >> (HASHWORDBITS - 8);
44	  hval ^= g;
45	}
46    }
47  return hval;
48}
49