/* Compute hash value for given string according to ELF standard.

   Copyright (C) 1995-2018 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 */