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 } 49
