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1 /************************************************************************************
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2
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3 PublicHeader: OVR
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4 Filename : OVR_Timer.h
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5 Content : Provides static functions for precise timing
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6 Created : September 19, 2012
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7 Notes :
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8
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9 Copyright : Copyright 2012 Oculus VR, Inc. All Rights reserved.
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10
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11 Use of this software is subject to the terms of the Oculus license
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12 agreement provided at the time of installation or download, or which
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13 otherwise accompanies this software in either electronic or hard copy form.
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14
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15 ************************************************************************************/
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16
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17 #ifndef OVR_Timer_h
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18 #define OVR_Timer_h
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19
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20 #include "OVR_Types.h"
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21
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22 namespace OVR {
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23
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24 //-----------------------------------------------------------------------------------
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25 // ***** Timer
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26
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27 // Timer class defines a family of static functions used for application
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28 // timing and profiling.
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29
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30 class Timer
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31 {
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32 public:
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33 enum {
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34 MsPerSecond = 1000, // Milliseconds in one second.
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35 MksPerMs = 1000, // Microseconds in one millisecond.
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36 MksPerSecond = MsPerSecond * MksPerMs
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37 };
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38
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39
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40 // ***** Timing APIs for Application
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41 // These APIs should be used to guide animation and other program functions
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42 // that require precision.
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43
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44 // Returns ticks in milliseconds, as a 32-bit number. May wrap around every
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45 // 49.2 days. Use either time difference of two values of GetTicks to avoid
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46 // wrap-around. GetTicksMs may perform better then GetTicks.
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47 static UInt32 OVR_STDCALL GetTicksMs();
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48
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49 // GetTicks returns general-purpose high resolution application timer value,
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50 // measured in microseconds (mks, or 1/1000000 of a second). The actual precision
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51 // is system-specific and may be much lower, such as 1 ms.
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52 static UInt64 OVR_STDCALL GetTicks();
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53
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54
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55 // ***** Profiling APIs.
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56 // These functions should be used for profiling, but may have system specific
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57 // artifacts that make them less appropriate for general system use.
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58 // On Win32, for example these rely on QueryPerformanceConter may have
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59 // problems with thread-core switching and power modes.
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60
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61 // Return a hi-res timer value in mks (1/1000000 of a sec).
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62 // Generally you want to call this at the start and end of an
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63 // operation, and pass the difference to
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64 // TicksToSeconds() to find out how long the operation took.
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65 static UInt64 OVR_STDCALL GetProfileTicks();
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66
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67 // More convenient zero-based profile timer in seconds. First call initializes
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68 // the "zero" value; future calls return the difference. Not thread safe for first call.
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69 // Due to low precision of Double, may malfunction after long runtime.
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70 static double OVR_STDCALL GetProfileSeconds();
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71
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72 // Get the raw cycle counter value, providing the maximum possible timer resolution.
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73 static UInt64 OVR_STDCALL GetRawTicks();
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74 static UInt64 OVR_STDCALL GetRawFrequency();
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75
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76
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77 // ***** Tick and time unit conversion.
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78
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79 // Convert micro-second ticks value into seconds value.
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80 static inline double TicksToSeconds(UInt64 ticks)
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81 {
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82 return static_cast<double>(ticks) * (1.0 / (double)MksPerSecond);
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83 }
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84 // Convert Raw or frequency-unit ticks to seconds based on specified frequency.
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85 static inline double RawTicksToSeconds(UInt64 rawTicks, UInt64 rawFrequency)
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86 {
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87 return static_cast<double>(rawTicks) * rawFrequency;
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88 }
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89
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90 private:
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91 friend class System;
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92 // System called during program startup/shutdown.
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93 static void initializeTimerSystem();
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94 static void shutdownTimerSystem();
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95 };
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96
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97
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98 } // Scaleform::Timer
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99
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100 #endif
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