1  /* Shift unaligned word read  Generic C version.
       2     Copyright (C) 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     <http://www.gnu.org/licenses/>.  */
      18  
      19  #ifndef _STRING_SHIFT_H
      20  #define _STRING_SHIFT_H 1
      21  
      22  #include <endian.h>
      23  #include <limits.h>
      24  #include <stdint.h>
      25  #include <string-fza.h>
      26  
      27  /* Return the mask WORD shifted based on S_INT address value, to ignore
      28     values not presented in the aligned word read.  */
      29  static __always_inline find_t
      30  shift_find (find_t word, uintptr_t s)
      31  {
      32    if (__BYTE_ORDER == __LITTLE_ENDIAN)
      33      return word >> (CHAR_BIT * (s % sizeof (op_t)));
      34    else
      35      return word << (CHAR_BIT * (s % sizeof (op_t)));
      36  }
      37  
      38  /* Mask off the bits defined for the S alignment value, or return WORD if
      39     S is 0.  */
      40  static __always_inline find_t
      41  shift_find_last (find_t word, uintptr_t s)
      42  {
      43    s = s % sizeof (op_t);
      44    if (s == 0)
      45      return word;
      46    if (__BYTE_ORDER == __LITTLE_ENDIAN)
      47      return word & ~(((op_t)-1) << (s * CHAR_BIT));
      48    else
      49      return word & ~(((op_t)-1) >> (s * CHAR_BIT));
      50  }
      51  
      52  #endif /* _STRING_SHIFT_H */