diff options
Diffstat (limited to 'libs/pbd/ffs.cc')
-rw-r--r-- | libs/pbd/ffs.cc | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/libs/pbd/ffs.cc b/libs/pbd/ffs.cc new file mode 100644 index 0000000000..557504f14e --- /dev/null +++ b/libs/pbd/ffs.cc @@ -0,0 +1,49 @@ +/* + 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 +} + +} |