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/*
Copyright (C) 2013 Tim Mayberry
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "pbd/ffs.h"
#ifndef COMPILER_MSVC
#include <strings.h>
#endif
namespace PBD {
int
ffs (int x)
{
#if defined (COMPILER_MINGW)
return __builtin_ffs(x);
#elif defined (COMPILER_MSVC)
unsigned long index;
#ifdef WIN64
if (0 != _BitScanForward64(&index, (__int64)x))
#else
if (0 != _BitScanForward(&index, (unsigned long)x))
#endif
index++; // Make the result 1-based
else
index = 0; // All bits were zero
return (int)index;
#else
return ::ffs(x);
#endif
}
}
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