45 lines
825 B
C++
45 lines
825 B
C++
#ifndef OSRM_UTIL_MSB_HPP
|
|
#define OSRM_UTIL_MSB_HPP
|
|
|
|
#include <boost/assert.hpp>
|
|
|
|
#include <cstdint>
|
|
#include <utility>
|
|
|
|
namespace osrm
|
|
{
|
|
namespace util
|
|
{
|
|
|
|
// get the msb of an integer
|
|
// return 0 for integers without msb
|
|
template <typename T> std::size_t msb(T value)
|
|
{
|
|
static_assert(std::is_integral<T>::value && !std::is_signed<T>::value, "Integer required.");
|
|
std::size_t msb = 0;
|
|
while (value > 0)
|
|
{
|
|
value >>= 1u;
|
|
msb++;
|
|
}
|
|
BOOST_ASSERT(msb > 0);
|
|
return msb - 1;
|
|
}
|
|
|
|
#if (defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)) && __x86_64__
|
|
inline std::size_t msb(std::uint64_t v)
|
|
{
|
|
BOOST_ASSERT(v > 0);
|
|
return 63UL - __builtin_clzl(v);
|
|
}
|
|
inline std::size_t msb(std::uint32_t v)
|
|
{
|
|
BOOST_ASSERT(v > 0);
|
|
return 31UL - __builtin_clz(v);
|
|
}
|
|
#endif
|
|
}
|
|
}
|
|
|
|
#endif
|