PublicUtility/CAHostTimeBase.h

/*
     File: CAHostTimeBase.h 
 Abstract:  Part of CoreAudio Utility Classes  
  Version: 1.01 
  
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*/
#if !defined(__CAHostTimeBase_h__)
#define __CAHostTimeBase_h__
 
//=============================================================================
//  Includes
//=============================================================================
 
#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__)
    #include <CoreAudio/CoreAudioTypes.h>
#else
    #include <CoreAudioTypes.h>
#endif
 
#if TARGET_OS_MAC
    #include <mach/mach_time.h>
#elif TARGET_OS_WIN32
    #include <windows.h>
#else
    #error  Unsupported operating system
#endif
 
#include "CADebugMacros.h"
 
//=============================================================================
//  CAHostTimeBase
//
//  This class provides platform independent access to the host's time base.
//=============================================================================
 
#if CoreAudio_Debug
//  #define Log_Host_Time_Base_Parameters   1
//  #define Track_Host_TimeBase             1
#endif
 
class   CAHostTimeBase
{
 
public:
    static UInt64   ConvertToNanos(UInt64 inHostTime);
    static UInt64   ConvertFromNanos(UInt64 inNanos);
 
    static UInt64   GetTheCurrentTime();
#if TARGET_OS_MAC
    static UInt64   GetCurrentTime() { return GetTheCurrentTime(); }
#endif
    static UInt64   GetCurrentTimeInNanos();
 
    static Float64  GetFrequency() { if(!sIsInited) { Initialize(); } return sFrequency; }
    static Float64  GetInverseFrequency() { if(!sIsInited) { Initialize(); } return sInverseFrequency; }
    static UInt32   GetMinimumDelta() { if(!sIsInited) { Initialize(); } return sMinDelta; }
 
    static UInt64   AbsoluteHostDeltaToNanos(UInt64 inStartTime, UInt64 inEndTime);
    static SInt64   HostDeltaToNanos(UInt64 inStartTime, UInt64 inEndTime);
 
private:
    static void     Initialize();
    
    static bool     sIsInited;
    
    static Float64  sFrequency;
    static Float64  sInverseFrequency;
    static UInt32   sMinDelta;
    static UInt32   sToNanosNumerator;
    static UInt32   sToNanosDenominator;
    static UInt32   sFromNanosNumerator;
    static UInt32   sFromNanosDenominator;
    static bool     sUseMicroseconds;
#if Track_Host_TimeBase
    static UInt64   sLastTime;
#endif
};
 
inline UInt64   CAHostTimeBase::GetTheCurrentTime()
{
    UInt64 theTime = 0;
 
    #if TARGET_OS_MAC
        theTime = mach_absolute_time();
    #elif TARGET_OS_WIN32
        LARGE_INTEGER theValue;
        QueryPerformanceCounter(&theValue);
        theTime = *((UInt64*)&theValue);
    #endif
    
    #if Track_Host_TimeBase
        if(sLastTime != 0)
        {
            if(theTime <= sLastTime)
            {
                DebugMessageN2("CAHostTimeBase::GetTheCurrentTime: the current time is earlier than the last time, now: %qd, then: %qd", theTime, sLastTime);
            }
            sLastTime = theTime;
        }
        else
        {
            sLastTime = theTime;
        }
    #endif
 
    return theTime;
}
 
inline UInt64   CAHostTimeBase::ConvertToNanos(UInt64 inHostTime)
{
    if(!sIsInited)
    {
        Initialize();
    }
    
    Float64 theNumerator = static_cast<Float64>(sToNanosNumerator);
    Float64 theDenominator = static_cast<Float64>(sToNanosDenominator);
    Float64 theHostTime = static_cast<Float64>(inHostTime);
 
    Float64 thePartialAnswer = theHostTime / theDenominator;
    Float64 theFloatAnswer = thePartialAnswer * theNumerator;
    UInt64 theAnswer = static_cast<UInt64>(theFloatAnswer);
 
    //Assert(!((theNumerator > theDenominator) && (theAnswer < inHostTime)), "CAHostTimeBase::ConvertToNanos: The conversion wrapped");
    //Assert(!((theDenominator > theNumerator) && (theAnswer > inHostTime)), "CAHostTimeBase::ConvertToNanos: The conversion wrapped");
 
    return theAnswer;
}
 
inline UInt64   CAHostTimeBase::ConvertFromNanos(UInt64 inNanos)
{
    if(!sIsInited)
    {
        Initialize();
    }
 
    Float64 theNumerator = static_cast<Float64>(sToNanosNumerator);
    Float64 theDenominator = static_cast<Float64>(sToNanosDenominator);
    Float64 theNanos = static_cast<Float64>(inNanos);
 
    Float64 thePartialAnswer = theNanos / theNumerator;
    Float64 theFloatAnswer = thePartialAnswer * theDenominator;
    UInt64 theAnswer = static_cast<UInt64>(theFloatAnswer);
 
    //Assert(!((theDenominator > theNumerator) && (theAnswer < inNanos)), "CAHostTimeBase::ConvertToNanos: The conversion wrapped");
    //Assert(!((theNumerator > theDenominator) && (theAnswer > inNanos)), "CAHostTimeBase::ConvertToNanos: The conversion wrapped");
 
    return theAnswer;
}
 
 
inline UInt64   CAHostTimeBase::GetCurrentTimeInNanos()
{
    return ConvertToNanos(GetTheCurrentTime());
}
 
inline UInt64   CAHostTimeBase::AbsoluteHostDeltaToNanos(UInt64 inStartTime, UInt64 inEndTime)
{
    UInt64 theAnswer;
    
    if(inStartTime <= inEndTime)
    {
        theAnswer = inEndTime - inStartTime;
    }
    else
    {
        theAnswer = inStartTime - inEndTime;
    }
    
    return ConvertToNanos(theAnswer);
}
 
inline SInt64   CAHostTimeBase::HostDeltaToNanos(UInt64 inStartTime, UInt64 inEndTime)
{
    SInt64 theAnswer;
    SInt64 theSign = 1;
    
    if(inStartTime <= inEndTime)
    {
        theAnswer = inEndTime - inStartTime;
    }
    else
    {
        theAnswer = inStartTime - inEndTime;
        theSign = -1;
    }
    
    return theSign * ConvertToNanos(theAnswer);
}
 
#endif