1 /* hash-string.h - Description of GNU message catalog format: string hashing function. */
3 /* Copyright (C) 1995, 1997, 1998, 2000, 2001, 2005-2009 Free Software Foundation, Inc.
5 This file is part of GNU Bash.
7 Bash is free software: you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation, either version 3 of the License, or
10 (at your option) any later version.
12 Bash is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with Bash. If not, see <http://www.gnu.org/licenses/>.
21 /* @@ end of prolog @@ */
24 # if __STDC__ || defined __GNUC__ || defined __SUNPRO_C || defined __cplusplus || __PROTOTYPES
25 # define PARAMS(Args) Args
27 # define PARAMS(Args) ()
31 /* We assume to have `unsigned long int' value with at least 32 bits. */
32 #define HASHWORDBITS 32
35 /* Defines the so called `hashpjw' function by P.J. Weinberger
36 [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
37 1986, 1987 Bell Telephone Laboratories, Inc.] */
38 static unsigned long int hash_string PARAMS ((const char *__str_param));
40 static inline unsigned long int
41 hash_string (str_param)
42 const char *str_param;
44 unsigned long int hval, g;
45 const char *str = str_param;
47 /* Compute the hash value for the given string. */
52 hval += (unsigned long int) *str++;
53 g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4));
56 hval ^= g >> (HASHWORDBITS - 8);