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

     2 // All rights reserved.

     3 // This component and the accompanying materials are made available

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

     5 // which accompanies this distribution, and is available

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

     7 //

     8 // Initial Contributors:

     9 // Nokia Corporation - initial contribution.

    10 //

    11 // Contributors:

    12 //

    13 // Description:

    14 // e32\nkern\win32\ncutilf.cpp

    15 // 

    16 //

    17 

    18 #include "nk_priv.h"

    19 

    20 // Win32 fast counter implementation

    21 

    22 static TBool FastCounterSupported = FALSE;

    23 static TInt FastCounterShift;

    24 static TInt FastCounterAdjustedFreq;

    25 

    26 /** Initialise the fast counter.

    27 

    28     Check whether a high performance counter is available and determine its

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

    30     at most every 16 seconds.

    31 */

    32 void FastCounterInit()

    33 	{

    34 	// Test support by getting count - QueryPerformanceFrequency can succeed

    35 	// even if not supported

    36 	LARGE_INTEGER count;

    37 	count.QuadPart = 0;

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

    39 		return;  // not supported

    40 	

    41 	LARGE_INTEGER freq;

    42 	freq.QuadPart = 0;

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

    44 		return;  // not supported

    45 

    46 	TInt mso = __e32_find_ms1_32(freq.LowPart);

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

    48 	

    49 	FastCounterSupported = TRUE;

    50 	FastCounterAdjustedFreq = freq.LowPart >> FastCounterShift;	

    51 	}

    52     

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

    54 

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

    56     tick count instead.

    57 */

    58 EXPORT_C TUint32 NKern::FastCounter()

    59 	{

    60 	if (FastCounterSupported)

    61 		{

    62 		LARGE_INTEGER count;

    63 		count.QuadPart = 0;

    64 		QueryPerformanceCounter(&count);

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

    66 		}

    67 	else

    68 		return NTickCount();

    69 	}

    70 

    71 

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

    73 */

    74 EXPORT_C TInt NKern::FastCounterFrequency()

    75 	{

    76 	if (FastCounterSupported)

    77 		return FastCounterAdjustedFreq;

    78 	else

    79 		return 1000000 / TickPeriod();

    80 	}