diff options
Diffstat (limited to 'newlib/libc/sys/linux/include/dl-hash.h')
-rw-r--r-- | newlib/libc/sys/linux/include/dl-hash.h | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/newlib/libc/sys/linux/include/dl-hash.h b/newlib/libc/sys/linux/include/dl-hash.h new file mode 100644 index 000000000..e0f7a4944 --- /dev/null +++ b/newlib/libc/sys/linux/include/dl-hash.h @@ -0,0 +1,74 @@ +/* Compute hash value for given string according to ELF standard. + Copyright (C) 1995, 1996, 1997, 1998 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 inline unsigned int +_dl_elf_hash (const unsigned char *name) +{ + 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 */ |