string/ffsll.c

   1 /* Copyright (C) 1991-2024 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <limits.h>
  19 #define ffsl __something_else
  20 #include <string.h>
  21 #undef  ffsll
  22 #include <math-use-builtins.h>
  23 #include <libc-diag.h>
  24
  25 /* Find the first bit set in I.  */
  26 int
  27 __ffsll (long long int i)
  28 {
  29 #if USE_FFSLL_BUILTIN
  30   return __builtin_ffsll (i);
  31 #else
  32   unsigned long long int x = i & -i;
  33
  34   if (x <= 0xffffffff)
  35     return ffs (i);
  36   else
  37     return 32 + ffs (i >> 32);
  38 #endif
  39 }
  40 weak_alias (__ffsll, ffsll)
  41
  42 #if ULONG_MAX != UINT_MAX
  43 #undef ffsl
  44 weak_alias (ffsll, ffsl)
  45 #endif