1/* Description of GNU message catalog format: string hashing function.
2   Copyright (C) 1995, 1997, 1998, 2000, 2001 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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301,
17   USA.  */
18
19/* @@ end of prolog @@ */
20
21#ifndef PARAMS
22# if __STDC__ || defined __GNUC__ || defined __SUNPRO_C || defined __cplusplus || __PROTOTYPES
23#  define PARAMS(Args) Args
24# else
25#  define PARAMS(Args) ()
26# endif
27#endif
28
29/* We assume to have `unsigned long int' value with at least 32 bits.  */
30#define HASHWORDBITS 32
31
32
33/* Defines the so called `hashpjw' function by P.J. Weinberger
34   [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
35   1986, 1987 Bell Telephone Laboratories, Inc.]  */
36static unsigned long int hash_string PARAMS ((const char *__str_param));
37
38static inline unsigned long int
39hash_string (str_param)
40     const char *str_param;
41{
42  unsigned long int hval, g;
43  const char *str = str_param;
44
45  /* Compute the hash value for the given string.  */
46  hval = 0;
47  while (*str != '\0')
48    {
49      hval <<= 4;
50      hval += (unsigned long int) *str++;
51      g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4));
52      if (g != 0)
53	{
54	  hval ^= g >> (HASHWORDBITS - 8);
55	  hval ^= g;
56	}
57    }
58  return hval;
59}
60