75 lines
2.0 KiB
C
75 lines
2.0 KiB
C
/* 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 */
|