boostorg/intrusive
1
0
Fork 1
mirror of https://github.com/boostorg/intrusive.git synced 2025-08-05 15:34:35 +02:00
Code Issues Packages Projects Releases Wiki Activity

Added is_pow2/static_is_pow2/ceil_pow2/previous_or_equal_pow2

Browse Source
This commit is contained in:
Ion Gaztañaga
2015-09-07 18:25:08 +02:00
parent 0f2714b8e8
commit 79272de8ba
1 changed files with 21 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

22
include/boost/intrusive/detail/math.hpp
View File

@@ -23,6 +23,7 @@
#include <cstddef> #include <cstddef>
#include <climits> #include <climits>
#include <boost/intrusive/detail/mpl.hpp>
namespace boost { namespace boost {
namespace intrusive { namespace intrusive {
@@ -227,9 +228,28 @@ inline float fast_log2 (float val)
return val + static_cast<float>(log_2); return val + static_cast<float>(log_2);
} }
inline bool is_pow2(std::size_t x)
{ return (x & (x-1)) == 0; }
template<std::size_t N>
struct static_is_pow2
{
static const bool value = (N & (N-1)) == 0;
};
inline std::size_t ceil_log2 (std::size_t x) inline std::size_t ceil_log2 (std::size_t x)
{ {
return static_cast<std::size_t>((x & (x-1)) != 0) + floor_log2(x); return static_cast<std::size_t>(!(is_pow2)(x)) + floor_log2(x);
}
inline std::size_t ceil_pow2 (std::size_t x)
{
return std::size_t(1u) << (ceil_log2)(x);
}
inline std::size_t previous_or_equal_pow2(std::size_t x)
{
return std::size_t(1u) << floor_log2(x);
} }
template<class SizeType, std::size_t N> template<class SizeType, std::size_t N>