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// Copyright Oliver Kowalke 2009.
// 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 CYCLE_X86_64_H
#define CYCLE_X86_64_H
#include <algorithm>
#include <numeric>
#include <cstddef>
#include <vector>
#include <boost/assert.hpp>
#include <boost/bind.hpp>
#include <boost/cstdint.hpp>
#define BOOST_CONTEXT_CYCLE
typedef boost::uint64_t cycle_type;
#if _MSC_VER >= 1400
# include <intrin.h>
# pragma intrinsic(__rdtsc)
inline
cycle_type cycles()
{ return __rdtsc(); }
#elif defined(__INTEL_COMPILER) || defined(__ICC) || defined(_ECC) || defined(__ICL)
inline
cycle_type cycles()
{ return __rdtsc(); }
#elif defined(__GNUC__) || defined(__SUNPRO_C)
inline
cycle_type cycles()
{
boost::uint32_t lo, hi;
__asm__ __volatile__ (
"xorl %%eax, %%eax\n"
"cpuid\n"
::: "%rax", "%rbx", "%rcx", "%rdx"
);
__asm__ __volatile__ ("rdtsc" : "=a" (lo), "=d" (hi) );
__asm__ __volatile__ (
"xorl %%eax, %%eax\n"
"cpuid\n"
::: "%rax", "%rbx", "%rcx", "%rdx"
);
return ( cycle_type)hi << 32 | lo;
}
#else
# error "this compiler is not supported"
#endif
struct cycle_overhead
{
cycle_type operator()()
{
cycle_type start( cycles() );
return cycles() - start;
}
};
inline
cycle_type overhead_cycle()
{
std::size_t iterations( 10);
std::vector< cycle_type > overhead( iterations, 0);
for ( std::size_t i( 0); i < iterations; ++i)
std::generate(
overhead.begin(), overhead.end(),
cycle_overhead() );
BOOST_ASSERT( overhead.begin() != overhead.end() );
return std::accumulate( overhead.begin(), overhead.end(), 0) / iterations;
}
#endif // CYCLE_X86_64_H
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