OVR_Timer.cpp
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00001 /************************************************************************************
00002 
00003 Filename    :   OVR_Timer.cpp
00004 Content     :   Provides static functions for precise timing
00005 Created     :   September 19, 2012
00006 Notes       : 
00007 
00008 Copyright   :   Copyright 2012 Oculus VR, Inc. All Rights reserved.
00009 
00010 Use of this software is subject to the terms of the Oculus license
00011 agreement provided at the time of installation or download, or which
00012 otherwise accompanies this software in either electronic or hard copy form.
00013 
00014 ************************************************************************************/
00015 
00016 #include "OVR_Timer.h"
00017 
00018 #if defined (OVR_OS_WIN32)
00019 #include <windows.h>
00020 
00021 #else
00022 #include <sys/time.h>
00023 #endif
00024 
00025 namespace OVR {
00026 
00027 //-----------------------------------------------------------------------------------
00028 // ***** Timer Class
00029 
00030 UInt64 Timer::GetProfileTicks()
00031 {
00032     return (GetRawTicks() * MksPerSecond) / GetRawFrequency();
00033 }
00034 double Timer::GetProfileSeconds()
00035 {
00036     static UInt64 StartTime = GetProfileTicks();
00037     return TicksToSeconds(GetProfileTicks()-StartTime);
00038 }
00039 
00040 
00041 //------------------------------------------------------------------------
00042 // *** Win32 Specific Timer
00043 
00044 #if (defined (OVR_OS_WIN32))
00045 
00046 CRITICAL_SECTION WinAPI_GetTimeCS;
00047 volatile UInt32  WinAPI_OldTime = 0;
00048 volatile UInt32  WinAPI_WrapCounter = 0;
00049 
00050 
00051 UInt32 Timer::GetTicksMs()
00052 {
00053     return timeGetTime();
00054 }
00055 
00056 UInt64 Timer::GetTicks()
00057 {
00058     DWORD  ticks = timeGetTime();
00059     UInt64 result;
00060 
00061     // On Win32 QueryPerformanceFrequency is unreliable due to SMP and
00062     // performance levels, so use this logic to detect wrapping and track
00063     // high bits.
00064     ::EnterCriticalSection(&WinAPI_GetTimeCS);
00065 
00066     if (WinAPI_OldTime > ticks)
00067         WinAPI_WrapCounter++;
00068     WinAPI_OldTime = ticks;
00069 
00070     result = (UInt64(WinAPI_WrapCounter) << 32) | ticks;
00071     ::LeaveCriticalSection(&WinAPI_GetTimeCS);
00072 
00073     return result * MksPerMs;
00074 }
00075 
00076 UInt64 Timer::GetRawTicks()
00077 {
00078     LARGE_INTEGER li;
00079     QueryPerformanceCounter(&li);
00080     return li.QuadPart;
00081 }
00082 
00083 UInt64 Timer::GetRawFrequency()
00084 {
00085     static UInt64 perfFreq = 0;
00086     if (perfFreq == 0)
00087     {
00088         LARGE_INTEGER freq;
00089         QueryPerformanceFrequency(&freq);
00090         perfFreq = freq.QuadPart;
00091     }
00092     return perfFreq;
00093 }
00094 
00095 void Timer::initializeTimerSystem()
00096 {
00097     timeBeginPeriod(1);
00098     InitializeCriticalSection(&WinAPI_GetTimeCS);
00099 
00100 }
00101 void Timer::shutdownTimerSystem()
00102 {
00103     DeleteCriticalSection(&WinAPI_GetTimeCS);
00104     timeEndPeriod(1);
00105 }
00106 
00107 #else   // !OVR_OS_WIN32
00108 
00109 
00110 //------------------------------------------------------------------------
00111 // *** Standard OS Timer     
00112 
00113 UInt32 Timer::GetTicksMs()
00114 {
00115     return (UInt32)(GetProfileTicks() / 1000);
00116 }
00117 // The profile ticks implementation is just fine for a normal timer.
00118 UInt64 Timer::GetTicks()
00119 {
00120     return GetProfileTicks();
00121 }
00122 
00123 void Timer::initializeTimerSystem()
00124 {
00125 }
00126 void Timer::shutdownTimerSystem()
00127 {
00128 }
00129 
00130 UInt64  Timer::GetRawTicks()
00131 {
00132     // TODO: prefer rdtsc when available?
00133 
00134     // Return microseconds.
00135     struct timeval tv;
00136     UInt64 result;
00137 
00138     gettimeofday(&tv, 0);
00139 
00140     result = (UInt64)tv.tv_sec * 1000000;
00141     result += tv.tv_usec;
00142 
00143     return result;
00144 }
00145 
00146 UInt64 Timer::GetRawFrequency()
00147 {
00148     return MksPerSecond;
00149 }
00150 
00151 #endif  // !OVR_OS_WIN32
00152 
00153 
00154 
00155 } // OVR
00156 


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autogenerated on Fri Aug 28 2015 11:53:11