1  /* Miscellaneous functions used in string implementations.  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_MISC_H
      20  #define _STRING_MISC_H 1
      21  
      22  #include <limits.h>
      23  #include <endian.h>
      24  #include <string-optype.h>
      25  
      26  /* Extract the byte at index IDX from word X, with index 0 being the
      27     least significant byte.  */
      28  static __always_inline unsigned char
      29  extractbyte (op_t x, unsigned int idx)
      30  {
      31    if (__BYTE_ORDER == __LITTLE_ENDIAN)
      32      return x >> (idx * CHAR_BIT);
      33    else
      34      return x >> (sizeof (x) - 1 - idx) * CHAR_BIT;
      35  }
      36  
      37  /* Setup an word with each byte being c_in.  For instance, on a 64 bits
      38     machine with input as 0xce the functions returns 0xcececececececece.  */
      39  static __always_inline op_t
      40  repeat_bytes (unsigned char c_in)
      41  {
      42    return ((op_t)-1 / 0xff) * c_in;
      43  }
      44  
      45  #endif /* _STRING_MISC_H */