Update.
[glibc.git] / locale / strlen-hash.h
blob2daeb03547af2c20d8adc22468e2975eb88682ba
1 /* Implements hashing function for string with known length.
2 Copyright (C) 1996, 1997 Free Software Foundation, Inc.
3 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
20 #include <sys/types.h>
22 /* We assume to have `size_t' value with at least 32 bits. */
23 #define HASHWORDBITS 32
26 /* Defines the so called `hashpjw' function by P.J. Weinberger
27 [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
28 1986, 1987 Bell Telephone Laboratories, Inc.] */
29 static size_t hash_string (const char *__str_param, size_t __len);
31 static inline size_t
32 hash_string (const char *str_param, size_t len)
34 size_t hval, g;
35 const char *end_str = str_param + len;
37 /* Compute the hash value for the given string. */
38 hval = len;
39 while (str_param != end_str)
41 hval <<= 4;
42 hval += (size_t) *str_param++;
43 g = hval & ((size_t) 0xf << (HASHWORDBITS - 4));
44 if (g != 0)
46 hval ^= g >> (HASHWORDBITS - 8);
47 hval ^= g;
50 return hval;