blob: dd6e6e8c9ecdaa59d413779a19c56a816df6ede0 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
|
// -----------------------------------------------------------
// lowest_bit.hpp
//
// Position of the lowest bit 'on'
//
// Copyright (c) 2003-2004, 2008 Gennaro Prota
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// -----------------------------------------------------------
#ifndef BOOST_LOWEST_BIT_HPP_GP_20030301
#define BOOST_LOWEST_BIT_HPP_GP_20030301
#include <assert.h>
#include "boost/pending/integer_log2.hpp"
namespace boost {
template <typename T>
int lowest_bit(T x) {
assert(x >= 1); // PRE
// clear all bits on except the rightmost one,
// then calculate the logarithm base 2
//
return boost::integer_log2<T>( x - ( x & (x-1) ) );
}
}
#endif // include guard
|
