| author | sl@SLION-WIN7.fritz.box |
| Fri, 15 Jun 2012 03:10:57 +0200 | |
| changeset 0 | bde4ae8d615e |
| permissions | -rw-r--r-- |
| sl@0 | 1 |
// ------------------------------------- |
| sl@0 | 2 |
// lowest_bit.hpp |
| sl@0 | 3 |
// |
| sl@0 | 4 |
// Position of the lowest bit 'on' |
| sl@0 | 5 |
// |
| sl@0 | 6 |
// (C) Copyright Gennaro Prota 2003 - 2004. |
| sl@0 | 7 |
// |
| sl@0 | 8 |
// Distributed under the Boost Software License, Version 1.0. |
| sl@0 | 9 |
// (See accompanying file LICENSE_1_0.txt or copy at |
| sl@0 | 10 |
// http://www.boost.org/LICENSE_1_0.txt) |
| sl@0 | 11 |
// |
| sl@0 | 12 |
// ------------------------------------------------------ |
| sl@0 | 13 |
|
| sl@0 | 14 |
#ifndef BOOST_LOWEST_BIT_HPP_GP_20030301 |
| sl@0 | 15 |
#define BOOST_LOWEST_BIT_HPP_GP_20030301 |
| sl@0 | 16 |
|
| sl@0 | 17 |
#include <cassert> |
| sl@0 | 18 |
#include "boost/pending/integer_log2.hpp" |
| sl@0 | 19 |
|
| sl@0 | 20 |
|
| sl@0 | 21 |
namespace boost {
|
| sl@0 | 22 |
|
| sl@0 | 23 |
template <typename T> |
| sl@0 | 24 |
int lowest_bit(T x) {
|
| sl@0 | 25 |
|
| sl@0 | 26 |
assert(x >= 1); // PRE |
| sl@0 | 27 |
|
| sl@0 | 28 |
// clear all bits on except the rightmost one, |
| sl@0 | 29 |
// then calculate the logarithm base 2 |
| sl@0 | 30 |
// |
| sl@0 | 31 |
return boost::integer_log2<T>( x - ( x & (x-1) ) ); |
| sl@0 | 32 |
|
| sl@0 | 33 |
} |
| sl@0 | 34 |
|
| sl@0 | 35 |
|
| sl@0 | 36 |
} |
| sl@0 | 37 |
|
| sl@0 | 38 |
|
| sl@0 | 39 |
#endif // include guard |