--- /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();
+ }