C / C++ / MFC

<br />
#include <mmsystem.h><br />
#pragma comment(lib, "winmm.lib")<br />
<br />
DWORD GetCPUSpeed() <br />
{<br />
	LARGE_INTEGER ulFreq, ulTicks, ulValue, ulStartCounter, ulEAX_EDX;<br />
<br />
	// Query for high-resolution counter frequency (this is not the CPU frequency):<br />
	if (QueryPerformanceFrequency(&ulFreq)) <br />
	{<br />
		// Query current value:<br />
		QueryPerformanceCounter(&ulTicks);<br />
		// Calculate end value (one second interval); this is (current + frequency)<br />
		ulValue.QuadPart = ulTicks.QuadPart + ulFreq.QuadPart;<br />
		// Read CPU time-stamp counter:<br />
		__asm RDTSC<br />
		// And save in ulEAX_EDX:<br />
		__asm mov ulEAX_EDX.LowPart, EAX<br />
		__asm mov ulEAX_EDX.HighPart, EDX<br />
		// Store starting counter value:<br />
		ulStartCounter.QuadPart = ulEAX_EDX.QuadPart;<br />
		// Loop for one second (measured with the high-resolution counter):<br />
		do <br />
		{<br />
			QueryPerformanceCounter(&ulTicks);<br />
		} while (ulTicks.QuadPart <= ulValue.QuadPart);<br />
		// Now again read CPU time-stamp counter:<br />
		__asm RDTSC<br />
		// And save:<br />
		__asm mov ulEAX_EDX.LowPart, EAX<br />
		__asm mov ulEAX_EDX.HighPart, EDX<br />
		<br />
		DWORD tmp = (DWORD) ((ulEAX_EDX.QuadPart - ulStartCounter.QuadPart) / 1000000);<br />
		timediff = tmp/10000000.0*0.001;<br />
		// Calculate number of cycles done in interval; 1000000 Hz = 1 MHz<br />
		return tmp;<br />
	} else {<br />
		// No high-resolution counter present:<br />
		return 0;<br />
	}<br />
}