1  /* Compute hash value for given string according to ELF standard.
       2     Copyright (C) 1998-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #ifndef _DL_HASH_H
      20  #define _DL_HASH_H	1
      21  
      22  
      23  /* This is the hashing function specified by the ELF ABI.  It is highly
      24     optimized for the PII processors.  Though it will run on i586 it
      25     would be much slower than the generic C implementation.  So don't
      26     use it.  */
      27  static unsigned int
      28  __attribute__ ((unused))
      29  _dl_elf_hash (const char *name)
      30  {
      31    unsigned int result;
      32    unsigned int temp0;
      33    unsigned int temp1;
      34  
      35    __asm__ __volatile__
      36      ("movzbl (%1),%2\n\t"
      37       "testl %2, %2\n\t"
      38       "jz 1f\n\t"
      39       "movl %2, %0\n\t"
      40       "movzbl 1(%1), %2\n\t"
      41       "jecxz 1f\n\t"
      42       "shll $4, %0\n\t"
      43       "addl %2, %0\n\t"
      44       "movzbl 2(%1), %2\n\t"
      45       "jecxz 1f\n\t"
      46       "shll $4, %0\n\t"
      47       "addl %2, %0\n\t"
      48       "movzbl 3(%1), %2\n\t"
      49       "jecxz 1f\n\t"
      50       "shll $4, %0\n\t"
      51       "addl %2, %0\n\t"
      52       "movzbl 4(%1), %2\n\t"
      53       "jecxz 1f\n\t"
      54       "shll $4, %0\n\t"
      55       "addl $5, %1\n\t"
      56       "addl %2, %0\n\t"
      57       "movzbl (%1), %2\n\t"
      58       "jecxz 1f\n"
      59       "2:\t"
      60       "shll $4, %0\n\t"
      61       "movl $0xf0000000, %3\n\t"
      62       "incl %1\n\t"
      63       "addl %2, %0\n\t"
      64       "andl %0, %3\n\t"
      65       "andl $0x0fffffff, %0\n\t"
      66       "shrl $24, %3\n\t"
      67       "movzbl (%1), %2\n\t"
      68       "xorl %3, %0\n\t"
      69       "testl %2, %2\n\t"
      70       "jnz 2b\n"
      71       "1:\t"
      72       : "=&r" (result), "=r" (name), "=&c" (temp0), "=&r" (temp1)
      73       : "0" (0), "1" ((const unsigned char *) name));
      74  
      75    return result;
      76  }
      77  
      78  #endif /* dl-hash.h */