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- Cache QueryPerformanceFrequency result

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This commit is contained in:
Ion Gaztañaga
2020-10-23 14:11:24 +02:00
parent 75eb880a56
commit ce209c4102
1 changed files with 26 additions and 16 deletions
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42
include/boost/move/detail/nsec_clock.hpp
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@ -25,6 +25,8 @@
#define BOOST_MOVE_DETAIL_NSEC_CLOCK_HPP
#include <boost/config.hpp>
#include <boost/cstdint.hpp>
#include <boost/cstdlib.hpp>
# if (defined(_WIN32) || defined(__WIN32__) || defined(WIN32))
@ -42,32 +44,40 @@
#include <boost/winapi/get_last_error.hpp>
#include <boost/winapi/error_codes.hpp>
#include <boost/assert.hpp>
#include <boost/core/ignore_unused.hpp>
namespace boost { namespace move_detail {
template<int Dummy>
struct QPFHolder
{
static inline double get_nsec_per_tic()
{
boost::winapi::LARGE_INTEGER_ freq;
boost::winapi::BOOL_ r = boost::winapi::QueryPerformanceFrequency( &freq );
boost::ignore_unused(r);
BOOST_ASSERT(r != 0 && "Boost::Move - get_nanosecs_per_tic Internal Error");
return double(1000000000.0L / freq.QuadPart);
}
static const double nanosecs_per_tic;
};
template<int Dummy>
const double QPFHolder<Dummy>::nanosecs_per_tic = get_nsec_per_tic();
inline boost::uint64_t nsec_clock() BOOST_NOEXCEPT
{
boost::winapi::LARGE_INTEGER_ freq;
if ( !boost::winapi::QueryPerformanceFrequency( &freq ) )
{
BOOST_ASSERT(0 && "Boost::Move - get_nanosecs_per_tic Internal Error");
return 0u;
}
double nanosecs_per_tic = double(1000000000.0L / freq.QuadPart);
double nanosecs_per_tic = QPFHolder<0>::nanosecs_per_tic;
boost::winapi::LARGE_INTEGER_ pcount;
if ( nanosecs_per_tic <= 0.0L )
{
BOOST_ASSERT(0 && "Boost::Move - get_nanosecs_per_tic Internal Error");
return 0u;
}
unsigned times=0;
while ( ! boost::winapi::QueryPerformanceCounter( &pcount ) )
while ( !boost::winapi::QueryPerformanceCounter( &pcount ) )
{
if ( ++times > 3 )
{
BOOST_ASSERT(0 && "Boost::Move - QueryPerformanceCounter Internal Error");
BOOST_ASSERT("Boost::Move - QueryPerformanceCounter Internal Error");
return 0u;
}
}