CAHostTimeBase.h

/*	Copyright: 	© Copyright 2005 Apple Computer, Inc. All rights reserved.

	Disclaimer:	IMPORTANT:  This Apple software is supplied to you by Apple Computer, Inc.
			("Apple") in consideration of your agreement to the following terms, and your
			use, installation, modification or redistribution of this Apple software
			constitutes acceptance of these terms.  If you do not agree with these terms,
			please do not use, install, modify or redistribute this Apple software.

			In consideration of your agreement to abide by the following terms, and subject
			to these terms, Apple grants you a personal, non-exclusive license, under AppleÕs
			copyrights in this original Apple software (the "Apple Software"), to use,
			reproduce, modify and redistribute the Apple Software, with or without
			modifications, in source and/or binary forms; provided that if you redistribute
			the Apple Software in its entirety and without modifications, you must retain
			this notice and the following text and disclaimers in all such redistributions of
			the Apple Software.  Neither the name, trademarks, service marks or logos of
			Apple Computer, Inc. may be used to endorse or promote products derived from the
			Apple Software without specific prior written permission from Apple.  Except as
			expressly stated in this notice, no other rights or licenses, express or implied,
			are granted by Apple herein, including but not limited to any patent rights that
			may be infringed by your derivative works or by other works in which the Apple
			Software may be incorporated.

			The Apple Software is provided by Apple on an "AS IS" basis.  APPLE MAKES NO
			WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED
			WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
			PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND OPERATION ALONE OR IN
			COMBINATION WITH YOUR PRODUCTS.

			IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR
			CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
			GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
			ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION, MODIFICATION AND/OR DISTRIBUTION
			OF THE APPLE SOFTWARE, HOWEVER CAUSED AND WHETHER UNDER THEORY OF CONTRACT, TORT
			(INCLUDING NEGLIGENCE), STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN
			ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*=============================================================================
	CAHostTimeBase.h

=============================================================================*/
#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 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 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