libs/port/ffs.c

   1 /*
   2  * ffs function
   3  *
   4  * Copyright 2004 Hans Leidekker
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library 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 GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  19  */
  20
  21 #include "config.h"
  22 #include "wine/port.h"
  23
  24 #ifndef HAVE_FFS
  25 int ffs( int x )
  26 {
  27     unsigned int y = (unsigned int)x;
  28
  29     if (y & 0x00000001) return 1;
  30     if (y & 0x00000002) return 2;
  31     if (y & 0x00000004) return 3;
  32     if (y & 0x00000008) return 4;
  33     if (y & 0x00000010) return 5;
  34     if (y & 0x00000020) return 6;
  35     if (y & 0x00000040) return 7;
  36     if (y & 0x00000080) return 8;
  37     if (y & 0x00000100) return 9;
  38     if (y & 0x00000200) return 10;
  39     if (y & 0x00000400) return 11;
  40     if (y & 0x00000800) return 12;
  41     if (y & 0x00001000) return 13;
  42     if (y & 0x00002000) return 14;
  43     if (y & 0x00004000) return 15;
  44     if (y & 0x00008000) return 16;
  45     if (y & 0x00010000) return 17;
  46     if (y & 0x00020000) return 18;
  47     if (y & 0x00040000) return 19;
  48     if (y & 0x00080000) return 20;
  49     if (y & 0x00100000) return 21;
  50     if (y & 0x00200000) return 22;
  51     if (y & 0x00400000) return 23;
  52     if (y & 0x00800000) return 24;
  53     if (y & 0x01000000) return 25;
  54     if (y & 0x02000000) return 26;
  55     if (y & 0x04000000) return 27;
  56     if (y & 0x08000000) return 28;
  57     if (y & 0x10000000) return 29;
  58     if (y & 0x20000000) return 30;
  59     if (y & 0x40000000) return 31;
  60     if (y & 0x80000000) return 32;
  61
  62     return 0;
  63 }
  64 #endif /* HAVE_FFS */