OVR_Timer.h
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00001 /************************************************************************************
00002 
00003 PublicHeader:   OVR
00004 Filename    :   OVR_Timer.h
00005 Content     :   Provides static functions for precise timing
00006 Created     :   September 19, 2012
00007 Notes       : 
00008 
00009 Copyright   :   Copyright 2012 Oculus VR, Inc. All Rights reserved.
00010 
00011 Use of this software is subject to the terms of the Oculus license
00012 agreement provided at the time of installation or download, or which
00013 otherwise accompanies this software in either electronic or hard copy form.
00014 
00015 ************************************************************************************/
00016 
00017 #ifndef OVR_Timer_h
00018 #define OVR_Timer_h
00019 
00020 #include "OVR_Types.h"
00021 
00022 namespace OVR {
00023     
00024 //-----------------------------------------------------------------------------------
00025 // ***** Timer
00026 
00027 // Timer class defines a family of static functions used for application
00028 // timing and profiling.
00029 
00030 class Timer
00031 {
00032 public:
00033     enum {
00034         MsPerSecond     = 1000, // Milliseconds in one second.
00035         MksPerMs        = 1000, // Microseconds in one millisecond.
00036         MksPerSecond    = MsPerSecond * MksPerMs
00037     };
00038 
00039 
00040     // ***** Timing APIs for Application    
00041     // These APIs should be used to guide animation and other program functions
00042     // that require precision.
00043 
00044     // Returns ticks in milliseconds, as a 32-bit number. May wrap around every
00045     // 49.2 days. Use either time difference of two values of GetTicks to avoid
00046     // wrap-around.  GetTicksMs may perform better then GetTicks.
00047     static UInt32  OVR_STDCALL GetTicksMs();
00048 
00049     // GetTicks returns general-purpose high resolution application timer value,
00050     // measured in microseconds (mks, or 1/1000000 of a second). The actual precision
00051     // is system-specific and may be much lower, such as 1 ms.
00052     static UInt64  OVR_STDCALL GetTicks();
00053 
00054     
00055     // ***** Profiling APIs.
00056     // These functions should be used for profiling, but may have system specific
00057     // artifacts that make them less appropriate for general system use.
00058     // On Win32, for example these rely on QueryPerformanceConter  may have
00059     // problems with thread-core switching and power modes.
00060 
00061     // Return a hi-res timer value in mks (1/1000000 of a sec).
00062     // Generally you want to call this at the start and end of an
00063     // operation, and pass the difference to
00064     // TicksToSeconds() to find out how long the operation took. 
00065     static UInt64  OVR_STDCALL GetProfileTicks();
00066 
00067     // More convenient zero-based profile timer in seconds. First call initializes 
00068     // the "zero" value; future calls return the difference. Not thread safe for first call.
00069     // Due to low precision of Double, may malfunction after long runtime.
00070     static double  OVR_STDCALL GetProfileSeconds();
00071 
00072     // Get the raw cycle counter value, providing the maximum possible timer resolution.
00073     static UInt64  OVR_STDCALL GetRawTicks();
00074     static UInt64  OVR_STDCALL GetRawFrequency();
00075 
00076     
00077     // ***** Tick and time unit conversion.
00078 
00079     // Convert micro-second ticks value into seconds value.
00080     static inline double TicksToSeconds(UInt64 ticks)
00081     {
00082         return static_cast<double>(ticks) * (1.0 / (double)MksPerSecond);
00083     }
00084     // Convert Raw or frequency-unit ticks to seconds based on specified frequency.
00085     static inline double RawTicksToSeconds(UInt64 rawTicks, UInt64 rawFrequency)
00086     {
00087         return static_cast<double>(rawTicks) * rawFrequency;
00088     }
00089 
00090 private:
00091     friend class System;
00092     // System called during program startup/shutdown.
00093     static void initializeTimerSystem();
00094     static void shutdownTimerSystem();
00095 };
00096 
00097 
00098 } // Scaleform::Timer
00099 
00100 #endif


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autogenerated on Fri Aug 28 2015 11:53:11