1
/* Implements a string hashing function.
2
Copyright (C) 1995, 1997 Free Software Foundation, Inc.
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)
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.
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. */
19
/* @@ end of prolog @@ */
23
# define PARAMS(Args) Args
25
# define PARAMS(Args) ()
29
/* We assume to have `unsigned long int' value with at least 32 bits. */
30
#define HASHWORDBITS 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.] */
36
static unsigned long hash_string PARAMS ((const char *__str_param));
38
static inline unsigned long
39
hash_string (str_param)
40
const char *str_param;
42
unsigned long int hval, g;
43
const char *str = str_param;
45
/* Compute the hash value for the given string. */
50
hval += (unsigned long) *str++;
51
g = hval & ((unsigned long) 0xf << (HASHWORDBITS - 4));
54
hval ^= g >> (HASHWORDBITS - 8);