Warning: This file is not a C or C++ file. It does not have highlighting.
| 1 | /* Implements hashing function for string with known length. |
|---|---|
| 2 | Copyright (C) 1996-2022 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, see |
| 17 | <https://www.gnu.org/licenses/>. */ |
| 18 | |
| 19 | #include <sys/types.h> |
| 20 | |
| 21 | /* We assume to have `size_t' 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 size_t hash_string (const char *__str_param, size_t __len); |
| 29 | |
| 30 | static inline size_t |
| 31 | hash_string (const char *str_param, size_t len) |
| 32 | { |
| 33 | size_t hval, g; |
| 34 | const char *end_str = str_param + len; |
| 35 | |
| 36 | /* Compute the hash value for the given string. */ |
| 37 | hval = len; |
| 38 | while (str_param != end_str) |
| 39 | { |
| 40 | hval <<= 4; |
| 41 | hval += (size_t) *str_param++; |
| 42 | g = hval & ((size_t) 0xf << (HASHWORDBITS - 4)); |
| 43 | if (g != 0) |
| 44 | { |
| 45 | hval ^= g >> (HASHWORDBITS - 8); |
| 46 | hval ^= g; |
| 47 | } |
| 48 | } |
| 49 | return hval; |
| 50 | } |
| 51 |
Warning: This file is not a C or C++ file. It does not have highlighting.