mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-17 02:20:10 +00:00
56 lines
1.9 KiB
C
56 lines
1.9 KiB
C
/* Copyright (C) 1991, 1992, 1997, 1998, 2004 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by Torbjorn Granlund (tege@sics.se).
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, write to the Free
|
|
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
|
|
02111-1307 USA. */
|
|
|
|
#include <limits.h>
|
|
#define ffsl __something_else
|
|
#include <string.h>
|
|
|
|
#undef ffs
|
|
|
|
/* Find the first bit set in I. */
|
|
int
|
|
__ffs (i)
|
|
int i;
|
|
{
|
|
static const unsigned char table[] =
|
|
{
|
|
0,1,2,2,3,3,3,3,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,
|
|
6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,
|
|
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
|
|
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
|
|
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,
|
|
8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8
|
|
};
|
|
unsigned int a;
|
|
unsigned int x = i & -i;
|
|
|
|
a = x <= 0xffff ? (x <= 0xff ? 0 : 8) : (x <= 0xffffff ? 16 : 24);
|
|
|
|
return table[x >> a] + a;
|
|
}
|
|
weak_alias (__ffs, ffs)
|
|
libc_hidden_builtin_def (ffs)
|
|
|
|
#if ULONG_MAX == UINT_MAX
|
|
#undef ffsl
|
|
weak_alias (__ffs, ffsl)
|
|
#endif
|