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