| /* Compute hash value for given string according to ELF standard. |
| Copyright (C) 1995,1996,1997,1998,2003,2005 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #ifndef _DL_HASH_H |
| #define _DL_HASH_H 1 |
| |
| |
| /* This is the hashing function specified by the ELF ABI. In the |
| first five operations no overflow is possible so we optimized it a |
| bit. */ |
| static unsigned int |
| _dl_elf_hash (const char *name_arg) |
| { |
| const unsigned char *name = (const unsigned char *) name_arg; |
| unsigned long int hash = 0; |
| if (*name != '\0') |
| { |
| hash = *name++; |
| if (*name != '\0') |
| { |
| hash = (hash << 4) + *name++; |
| if (*name != '\0') |
| { |
| hash = (hash << 4) + *name++; |
| if (*name != '\0') |
| { |
| hash = (hash << 4) + *name++; |
| if (*name != '\0') |
| { |
| hash = (hash << 4) + *name++; |
| while (*name != '\0') |
| { |
| unsigned long int hi; |
| hash = (hash << 4) + *name++; |
| hi = hash & 0xf0000000; |
| |
| /* The algorithm specified in the ELF ABI is as |
| follows: |
| |
| if (hi != 0) |
| hash ^= hi >> 24; |
| |
| hash &= ~hi; |
| |
| But the following is equivalent and a lot |
| faster, especially on modern processors. */ |
| |
| hash ^= hi; |
| hash ^= hi >> 24; |
| } |
| } |
| } |
| } |
| } |
| } |
| return hash; |
| } |
| |
| #endif /* dl-hash.h */ |