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a04eba3f | 1 | /* Description of GNU message catalog format: string hashing function. |
b0cacab0 | 2 | Copyright (C) 1995, 1997-1998, 2000-2003 Free Software Foundation, Inc. |
5bc5a89c | 3 | |
a04eba3f TT |
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) | |
5bc5a89c TT |
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 | |
a04eba3f TT |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Library General Public License for more details. | |
5bc5a89c TT |
13 | |
14 | You should have received a copy of the GNU Library General Public | |
a04eba3f | 15 | License along with this program; if not, write to the Free Software |
8785aaea | 16 | Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, |
a04eba3f | 17 | USA. */ |
5bc5a89c TT |
18 | |
19 | /* @@ end of prolog @@ */ | |
20 | ||
5bc5a89c TT |
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.] */ | |
a04eba3f | 28 | static inline unsigned long int |
b0cacab0 | 29 | hash_string (const char *str_param) |
5bc5a89c TT |
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; | |
b0cacab0 | 39 | hval += (unsigned char) *str++; |
a04eba3f | 40 | g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4)); |
5bc5a89c TT |
41 | if (g != 0) |
42 | { | |
43 | hval ^= g >> (HASHWORDBITS - 8); | |
44 | hval ^= g; | |
45 | } | |
46 | } | |
47 | return hval; | |
48 | } |