compat/ffsll.c

   1 /*****************************************************************************
   2  * ffsll.c: GNU ffsll() replacement
   3  *****************************************************************************
   4  * Copyright © 2015 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 #include <limits.h>
  26
  27 int ffsll(long long x)
  28 {
  29     for (unsigned i = 0; i < sizeof (x) * CHAR_BIT; i++)
  30         if ((x >> i) & 1)
  31             return i + 1;
  32     return 0;
  33 }