#include "StdAfx.h"
#include ".\Chronometer.h"
#include <windows.h>
#using <mscorlib.dll>

double TChronometer::Time1 = 0.0;
double TChronometer::Time2 = 0.0;
double TChronometer::CPUFrequence = 0.0;
bool   TChronometer::Initialized = false;

TChronometer::TChronometer(void)
{
}

TChronometer::~TChronometer(void)
{
}

double TChronometer::RDTSC()
{
	unsigned long a;
	unsigned long b;
	double x;

  __asm __emit 0x0F;
  __asm __emit 0x31; 

	__asm
	{
//		db   $0F , $31
		mov  [a] , eax
		mov  [b] , edx
	};

	x = b;
	x *= 4294967296;
	x += a;

	return x;
}

void TChronometer::Start()
{
	TChronometer::Time1 = TChronometer::RDTSC();
}

double TChronometer::Stop()
{
	TChronometer::Time2 = TChronometer::RDTSC();

	return 1000.0 * (TChronometer::Time2 - TChronometer::Time1) / TChronometer::CPUFrequence;
}

int TChronometer::Initialize()
{
	TChronometer::Initialized = false;

	unsigned __int64 Fwin;
	unsigned __int64 Twin_avant, Twin_apres;
	double Tcpu_avant;
	double Tcpu_apres;
	double Fcpu;

	// Lit la frequence du chronometre Windows
	if (!QueryPerformanceFrequency((LARGE_INTEGER*)&Fwin))
		return 0;

	// Avant
	Tcpu_avant = RDTSC();
	QueryPerformanceCounter((LARGE_INTEGER*)&Twin_avant);

	// Pause de 500 ms
	Sleep(500);

	// Apres
	Tcpu_apres = RDTSC();
	QueryPerformanceCounter((LARGE_INTEGER*)&Twin_apres);

	// Calcule la fréquence en MHz
	Fcpu = (Tcpu_apres - Tcpu_avant);
	Fcpu *= Fwin;
	Fcpu /= (double)(Twin_apres - Twin_avant);
	CPUFrequence = Fcpu;

	TChronometer::Initialized = true;

	return 1;
}