/[zanavi_public1]/navit/intl/hash-string.h
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Contents of /navit/intl/hash-string.h

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Fri Oct 28 21:19:04 2011 UTC (8 years, 3 months ago) by zoff99
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1 /* Description of GNU message catalog format: string hashing function.
2 Copyright (C) 1995, 1997-1998, 2000-2003 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
17 USA. */
18
19 /* @@ end of prolog @@ */
20
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.] */
28 static inline unsigned long int
29 hash_string (const char *str_param)
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;
39 hval += (unsigned char) *str++;
40 g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4));
41 if (g != 0)
42 {
43 hval ^= g >> (HASHWORDBITS - 8);
44 hval ^= g;
45 }
46 }
47 return hval;
48 }

   
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