// Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies).

 // All rights reserved.

 // This component and the accompanying materials are made available

 // under the terms of the License "Eclipse Public License v1.0"

 // which accompanies this distribution, and is available

 // at the URL "http://www.eclipse.org/legal/epl-v10.html".

 //

 // Initial Contributors:

 // Nokia Corporation - initial contribution.

 //

 // Contributors:

 //

 // Description:

 // e32\nkern\win32\ncutilf.cpp

 // 

 //

 #include "nk_priv.h"

 // Win32 fast counter implementation

 static TBool FastCounterSupported = FALSE;

 static TInt FastCounterShift;

 static TInt FastCounterAdjustedFreq;

 /** Initialise the fast counter.

     Check whether a high performance counter is available and determine its

     frequency.  Work out a scaling that allows a 32 bit counter value that wraps

     at most every 16 seconds.

 */

 void FastCounterInit()

 	{

 	// Test support by getting count - QueryPerformanceFrequency can succeed

 	// even if not supported

 	LARGE_INTEGER count;

 	count.QuadPart = 0;

 	if (!QueryPerformanceCounter(&count) || count.QuadPart == 0)

 		return;  // not supported

 	LARGE_INTEGER freq;

 	freq.QuadPart = 0;

 	if (!QueryPerformanceFrequency(&freq) || freq.QuadPart == 0)

 		return;  // not supported

 	TInt mso = __e32_find_ms1_32(freq.LowPart);

 	FastCounterShift = (mso > 27) ? mso - 27 : 0;

 	FastCounterSupported = TRUE;

 	FastCounterAdjustedFreq = freq.LowPart >> FastCounterShift;	

 	}

 /** Get the current value of the high performance counter.

     If a high performance counter is not available, this uses the millisecond

     tick count instead.

 */

 EXPORT_C TUint32 NKern::FastCounter()

 	{

 	if (FastCounterSupported)

 		{

 		LARGE_INTEGER count;

 		count.QuadPart = 0;

 		QueryPerformanceCounter(&count);

 		return (TUint32)(count.QuadPart >> FastCounterShift);

 		}

 	else

 		return NTickCount();

 	}

 /** Get the frequency of counter queried by NKern::FastCounter().

 */

 EXPORT_C TInt NKern::FastCounterFrequency()

 	{

 	if (FastCounterSupported)

 		return FastCounterAdjustedFreq;

 	else

 		return 1000000 / TickPeriod();

 	}