如何求一条语句或一段代码的cpu执行时间？

[itti]

Hi，
早上好。
如何求一条语句或一段代码的cpu执行时间？
谢谢

[无敌魔仙]

如果是 汇编指令 可以查表，但是如果是API函数我就不晓得了

[itti]

那
汇编指令 怎么用呢？

[aspnetwuxueyou]

// Timer.h
#pragma once

inline unsigned __int64 GetCycleCount(void)
{
_asm _emit 0x0F
_asm _emit 0x31
}

class KTimer
{
unsigned __int64 m_startcycle;
public:
unsigned __int64 m_overhead;

KTimer(void)
{
m_overhead = 0;
Start();
m_overhead = Stop();
}

void Start(void)
{
m_startcycle = GetCycleCount();
}

unsigned __int64 Stop(void)
{
return GetCycleCount() - m_startcycle - m_overhead;
}
};

[aspnetwuxueyou]

// Timer.h
#pragma once

inline unsigned __int64 GetCycleCount(void)
{
_asm _emit 0x0F
_asm _emit 0x31
}

class KTimer
{
unsigned __int64 m_startcycle;
public:
unsigned __int64 m_overhead;

KTimer(void)
{
m_overhead = 0;
Start();
m_overhead = Stop();
}

void Start(void)
{
m_startcycle = GetCycleCount();
}

unsigned __int64 Stop(void)
{
return GetCycleCount() - m_startcycle - m_overhead;
}
};

[aspnetwuxueyou]

//cpp file
#define STRICT
#define WIN32_LEAN_AND_MEAN

#include <windows.h>
#include <tchar.h>

#include "timer.h"

int WINAPI WinMain(HINSTANCE hInst, HINSTANCE, LPSTR lpCmd, int nShow)
{
KTimer timer;
TCHAR mess[128];

timer.Start();
Sleep(1000);
unsigned cpuspeed10 = (unsigned)( timer.Stop() / 100000 );

timer.Start();
CreateSolidBrush(RGB(0xAA, 0xAA, 0xAA));
unsigned time = (unsigned)timer.Stop();

wsprintf(mess, _T("CPU speed %d.%d mhz\n")
_T("KTimer overhead %d clock cycles\n")
_T("CreateSolidBrush %d clock cycles %d ns"),
cpuspeed10 / 10, cpuspeed10 % 10,
(unsigned) timer.m_overhead,
time, time * 10000 / cpuspeed10);

MessageBox(NULL, mess, _T("How fast is GDI?"), MB_OK);

return 0;
}