diff -r 000000000000 -r a41df078684a kernel/eka/nkern/win32/ncutilf.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/kernel/eka/nkern/win32/ncutilf.cpp Mon Oct 19 15:55:17 2009 +0100 @@ -0,0 +1,80 @@ +// 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(); + }