comparison: intl/hash-string.h
intl/hash-string.h
- changeset 347
- 20fdc56f4da4
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| 346:41b0f444e5a3 | 347:20fdc56f4da4 |
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| 1 /* Implements a string hashing function. | |
| 2 Copyright (C) 1995, 1997 Free Software Foundation, Inc. | |
| 3 | |
| 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. | |
| 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 | |
| 12 GNU General Public License for more details. | |
| 13 | |
| 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. */ | |
| 18 | |
| 19 /* @@ end of prolog @@ */ | |
| 20 | |
| 21 #ifndef PARAMS | |
| 22 # if __STDC__ | |
| 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 } |
