mirror of
https://sourceware.org/git/glibc.git
synced 2025-07-30 22:43:12 +03:00
2.5-18.1
This commit is contained in:
55
string/ffs.c
Normal file
55
string/ffs.c
Normal file
@ -0,0 +1,55 @@
|
||||
/* 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
|
Reference in New Issue
Block a user