sl@0: // Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0: // All rights reserved.
sl@0: // This component and the accompanying materials are made available
sl@0: // under the terms of the License "Eclipse Public License v1.0"
sl@0: // which accompanies this distribution, and is available
sl@0: // at the URL "http://www.eclipse.org/legal/epl-v10.html".
sl@0: //
sl@0: // Initial Contributors:
sl@0: // Nokia Corporation - initial contribution.
sl@0: //
sl@0: // Contributors:
sl@0: //
sl@0: // Description:
sl@0: // e32\nkern\win32\ncutilf.cpp
sl@0: // 
sl@0: //
sl@0: 
sl@0: #include "nk_priv.h"
sl@0: 
sl@0: // Win32 fast counter implementation
sl@0: 
sl@0: static TBool FastCounterSupported = FALSE;
sl@0: static TInt FastCounterShift;
sl@0: static TInt FastCounterAdjustedFreq;
sl@0: 
sl@0: /** Initialise the fast counter.
sl@0: 
sl@0:     Check whether a high performance counter is available and determine its
sl@0:     frequency.  Work out a scaling that allows a 32 bit counter value that wraps
sl@0:     at most every 16 seconds.
sl@0: */
sl@0: void FastCounterInit()
sl@0: 	{
sl@0: 	// Test support by getting count - QueryPerformanceFrequency can succeed
sl@0: 	// even if not supported
sl@0: 	LARGE_INTEGER count;
sl@0: 	count.QuadPart = 0;
sl@0: 	if (!QueryPerformanceCounter(&count) || count.QuadPart == 0)
sl@0: 		return;  // not supported
sl@0: 	
sl@0: 	LARGE_INTEGER freq;
sl@0: 	freq.QuadPart = 0;
sl@0: 	if (!QueryPerformanceFrequency(&freq) || freq.QuadPart == 0)
sl@0: 		return;  // not supported
sl@0: 
sl@0: 	TInt mso = __e32_find_ms1_32(freq.LowPart);
sl@0: 	FastCounterShift = (mso > 27) ? mso - 27 : 0;
sl@0: 	
sl@0: 	FastCounterSupported = TRUE;
sl@0: 	FastCounterAdjustedFreq = freq.LowPart >> FastCounterShift;	
sl@0: 	}
sl@0:     
sl@0: /** Get the current value of the high performance counter.
sl@0: 
sl@0:     If a high performance counter is not available, this uses the millisecond
sl@0:     tick count instead.
sl@0: */
sl@0: EXPORT_C TUint32 NKern::FastCounter()
sl@0: 	{
sl@0: 	if (FastCounterSupported)
sl@0: 		{
sl@0: 		LARGE_INTEGER count;
sl@0: 		count.QuadPart = 0;
sl@0: 		QueryPerformanceCounter(&count);
sl@0: 		return (TUint32)(count.QuadPart >> FastCounterShift);
sl@0: 		}
sl@0: 	else
sl@0: 		return NTickCount();
sl@0: 	}
sl@0: 
sl@0: 
sl@0: /** Get the frequency of counter queried by NKern::FastCounter().
sl@0: */
sl@0: EXPORT_C TInt NKern::FastCounterFrequency()
sl@0: 	{
sl@0: 	if (FastCounterSupported)
sl@0: 		return FastCounterAdjustedFreq;
sl@0: 	else
sl@0: 		return 1000000 / TickPeriod();
sl@0: 	}