merge from gcc
[binutils.git] / intl / hash-string.h
blobcacb38e479f8553cc97425f611845a34fab98647
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)
7 any later version.
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 @@ */
21 #ifndef PARAMS
22 # if __STDC__
23 # define PARAMS(Args) Args
24 # else
25 # define PARAMS(Args) ()
26 # endif
27 #endif
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. */
46 hval = 0;
47 while (*str != '\0')
49 hval <<= 4;
50 hval += (unsigned long) *str++;
51 g = hval & ((unsigned long) 0xf << (HASHWORDBITS - 4));
52 if (g != 0)
54 hval ^= g >> (HASHWORDBITS - 8);
55 hval ^= g;
58 return hval;