1/* Implements a string hashing function. 2 Copyright (C) 1995, 1997, 1998, 2000, 2003 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 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 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, write to the Free 17 Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 18 Boston, MA 02110-1301, USA. */ 19 20#ifdef HAVE_CONFIG_H 21# include <config.h> 22#endif 23 24/* Specification. */ 25#include "hash-string.h" 26 27 28/* Defines the so called `hashpjw' function by P.J. Weinberger 29 [see Aho/Sethi/Ullman, COMPILERS: Principles, Techniques and Tools, 30 1986, 1987 Bell Telephone Laboratories, Inc.] */ 31unsigned long int 32__hash_string (const char *str_param) 33{ 34 unsigned long int hval, g; 35 const char *str = str_param; 36 37 /* Compute the hash value for the given string. */ 38 hval = 0; 39 while (*str != '\0') 40 { 41 hval <<= 4; 42 hval += (unsigned char) *str++; 43 g = hval & ((unsigned long int) 0xf << (HASHWORDBITS - 4)); 44 if (g != 0) 45 { 46 hval ^= g >> (HASHWORDBITS - 8); 47 hval ^= g; 48 } 49 } 50 return hval; 51} 52