source: trunk/third/gnome-core/intl/hash-string.h @ 15328

Revision 15328, 1.8 KB checked in by ghudson, 24 years ago (diff)
This commit was generated by cvs2svn to compensate for changes in r15327, which included commits to RCS files with non-trunk default branches.
Line 
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/* @@ end of prolog @@ */
20
21#ifndef PARAMS
22# if __STDC__
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}
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