1*29619d2aSchristos /* $NetBSD: hash-string.h,v 1.1.1.1 2016/01/14 00:11:27 christos Exp $ */
2*29619d2aSchristos
3*29619d2aSchristos /* Description of GNU message catalog format: string hashing function.
4*29619d2aSchristos Copyright (C) 1995, 1997-1998, 2000-2003 Free Software Foundation, Inc.
5*29619d2aSchristos
6*29619d2aSchristos This program is free software; you can redistribute it and/or modify it
7*29619d2aSchristos under the terms of the GNU Library General Public License as published
8*29619d2aSchristos by the Free Software Foundation; either version 2, or (at your option)
9*29619d2aSchristos any later version.
10*29619d2aSchristos
11*29619d2aSchristos This program is distributed in the hope that it will be useful,
12*29619d2aSchristos but WITHOUT ANY WARRANTY; without even the implied warranty of
13*29619d2aSchristos MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14*29619d2aSchristos Library General Public License for more details.
15*29619d2aSchristos
16*29619d2aSchristos You should have received a copy of the GNU Library General Public
17*29619d2aSchristos License along with this program; if not, write to the Free Software
18*29619d2aSchristos Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
19*29619d2aSchristos USA. */
20*29619d2aSchristos
21*29619d2aSchristos /* @@ end of prolog @@ */
22*29619d2aSchristos
23*29619d2aSchristos /* We assume to have `unsigned long int' value with at least 32 bits. */
24*29619d2aSchristos #define HASHWORDBITS 32
25*29619d2aSchristos
26*29619d2aSchristos
27*29619d2aSchristos /* Defines the so called `hashpjw' function by P.J. Weinberger
28*29619d2aSchristos [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools,
29*29619d2aSchristos 1986, 1987 Bell Telephone Laboratories, Inc.] */
30*29619d2aSchristos static inline unsigned long int
hash_string(const char * str_param)31*29619d2aSchristos hash_string (const char *str_param)
32*29619d2aSchristos {
33*29619d2aSchristos unsigned long int hval, g;
34*29619d2aSchristos const char *str = str_param;
35*29619d2aSchristos
36*29619d2aSchristos /* Compute the hash value for the given string. */
37*29619d2aSchristos hval = 0;
38*29619d2aSchristos while (*str != '\0')
39*29619d2aSchristos {
40*29619d2aSchristos hval <<= 4;
41*29619d2aSchristos hval += (unsigned char) *str++;
42*29619d2aSchristos g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4));
43*29619d2aSchristos if (g != 0)
44*29619d2aSchristos {
45*29619d2aSchristos hval ^= g >> (HASHWORDBITS - 8);
46*29619d2aSchristos hval ^= g;
47*29619d2aSchristos }
48*29619d2aSchristos }
49*29619d2aSchristos return hval;
50*29619d2aSchristos }
51