1 /* Description of GNU message catalog format: string hashing function. 2 Copyright (C) 1995, 1997, 1998, 2000, 2001 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., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, 17 USA. */ 18 19 /* @@ end of prolog @@ */ 20 21 #ifndef PARAMS 22 # if __STDC__ || defined __GNUC__ || defined __SUNPRO_C || defined __cplusplus || __PROTOTYPES 23 # define PARAMS(Args) Args 24 # else 25 # define PARAMS(Args) () 26 # endif 27 #endif 28 29 /* We assume to have `unsigned long int' value with at least 32 bits. */ 30 #define HASHWORDBITS 32 31 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 int hash_string PARAMS ((const char *__str_param)); 37 38 static inline unsigned long int 39 hash_string (str_param) 40 const char *str_param; 41 { 42 unsigned long int hval, g; 43 const char *str = str_param; 44 45 /* Compute the hash value for the given string. */ 46 hval = 0; 47 while (*str != '\0') 48 { 49 hval <<= 4; 50 hval += (unsigned long int) *str++; 51 g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4)); 52 if (g != 0) 53 { 54 hval ^= g >> (HASHWORDBITS - 8); 55 hval ^= g; 56 } 57 } 58 return hval; 59 } 60
