diff options
Diffstat (limited to 'REORG.TODO/sysdeps/generic/dl-hash.h')
| -rw-r--r-- | REORG.TODO/sysdeps/generic/dl-hash.h | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/generic/dl-hash.h b/REORG.TODO/sysdeps/generic/dl-hash.h new file mode 100644 index 0000000000..4524381647 --- /dev/null +++ b/REORG.TODO/sysdeps/generic/dl-hash.h @@ -0,0 +1,75 @@ +/* Compute hash value for given string according to ELF standard. + Copyright (C) 1995-2017 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, see + <http://www.gnu.org/licenses/>. */ + +#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 +__attribute__ ((unused)) +_dl_elf_hash (const char *name_arg) +{ + const unsigned char *name = (const unsigned char *) name_arg; + unsigned long int hash = *name; + if (hash != 0 && name[1] != '\0') + { + hash = (hash << 4) + name[1]; + if (name[2] != '\0') + { + hash = (hash << 4) + name[2]; + if (name[3] != '\0') + { + hash = (hash << 4) + name[3]; + if (name[4] != '\0') + { + hash = (hash << 4) + name[4]; + name += 5; + 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 >> 24; + } + + /* Second part of the modified formula. This + operation can be lifted outside the loop. */ + hash &= 0x0fffffff; + } + } + } + } + return hash; +} + +#endif /* dl-hash.h */ |