1  /* Zero byte detection; indexes.  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_FZI_H
      20  #define _STRING_FZI_H 1
      21  
      22  #include <limits.h>
      23  #include <endian.h>
      24  #include <string-fza.h>
      25  
      26  static __always_inline int
      27  clz (find_t c)
      28  {
      29    if (sizeof (find_t) == sizeof (unsigned long))
      30      return __builtin_clzl (c);
      31    else
      32      return __builtin_clzll (c);
      33  }
      34  
      35  static __always_inline int
      36  ctz (find_t c)
      37  {
      38    if (sizeof (find_t) == sizeof (unsigned long))
      39      return __builtin_ctzl (c);
      40    else
      41      return __builtin_ctzll (c);
      42  }
      43  
      44  /* A subroutine for the index_zero functions.  Given a test word C, return
      45     the (memory order) index of the first byte (in memory order) that is
      46     non-zero.  */
      47  static __always_inline unsigned int
      48  index_first (find_t c)
      49  {
      50    int r;
      51    if (__BYTE_ORDER == __LITTLE_ENDIAN)
      52      r = ctz (c);
      53    else
      54      r = clz (c);
      55    return r / CHAR_BIT;
      56  }
      57  
      58  /* Similarly, but return the (memory order) index of the last byte that is
      59     non-zero.  */
      60  static __always_inline unsigned int
      61  index_last (find_t c)
      62  {
      63    int r;
      64    if (__BYTE_ORDER == __LITTLE_ENDIAN)
      65      r = clz (c);
      66    else
      67      r = ctz (c);
      68    return sizeof (find_t) - 1 - (r / CHAR_BIT);
      69  }
      70  
      71  #endif /* STRING_FZI_H */