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+/*
+     File: CARingBuffer.h
+ Abstract: Part of CoreAudio Utility Classes
+  Version: 1.1
+ 
+ Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple
+ Inc. ("Apple") in consideration of your agreement to the following
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+ 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 Apple's 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 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.
+ 
+ Copyright (C) 2014 Apple Inc. All Rights Reserved.
+ 
+*/
+#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__)
+	#include <CoreAudio/CoreAudioTypes.h>
+#else
+	#include <CoreAudioTypes.h>
+#endif
+
+
+#ifndef CARingBuffer_Header
+#define CARingBuffer_Header
+
+enum {
+	kCARingBufferError_OK = 0,
+	kCARingBufferError_TooMuch = 3, // fetch start time is earlier than buffer start time and fetch end time is later than buffer end time
+	kCARingBufferError_CPUOverload = 4 // the reader is unable to get enough CPU cycles to capture a consistent snapshot of the time bounds
+};
+
+typedef SInt32 CARingBufferError;
+
+const UInt32 kGeneralRingTimeBoundsQueueSize = 32;
+const UInt32 kGeneralRingTimeBoundsQueueMask = kGeneralRingTimeBoundsQueueSize - 1;
+
+class CARingBuffer {
+public:
+	typedef SInt64 SampleTime;
+
+	CARingBuffer();
+	~CARingBuffer();
+	
+	void					Allocate(int nChannels, UInt32 bytesPerFrame, UInt32 capacityFrames);
+								// capacityFrames will be rounded up to a power of 2
+	void					Deallocate();
+	
+	CARingBufferError	Store(const AudioBufferList *abl, UInt32 nFrames, SampleTime frameNumber);
+							// Copy nFrames of data into the ring buffer at the specified sample time.
+							// The sample time should normally increase sequentially, though gaps
+							// are filled with zeroes. A sufficiently large gap effectively empties
+							// the buffer before storing the new data. 
+							
+							// If frameNumber is less than the previous frame number, the behavior is undefined.
+							
+							// Return false for failure (buffer not large enough).
+				
+	CARingBufferError	Fetch(AudioBufferList *abl, UInt32 nFrames, SampleTime frameNumber);
+								// will alter mNumDataBytes of the buffers
+	
+	CARingBufferError	GetTimeBounds(SampleTime &startTime, SampleTime &endTime);
+	
+protected:
+
+	int						FrameOffset(SampleTime frameNumber) { return (frameNumber & mCapacityFramesMask) * mBytesPerFrame; }
+
+	CARingBufferError		ClipTimeBounds(SampleTime& startRead, SampleTime& endRead);
+	
+	// these should only be called from Store.
+	SampleTime				StartTime() const { return mTimeBoundsQueue[mTimeBoundsQueuePtr & kGeneralRingTimeBoundsQueueMask].mStartTime; }
+	SampleTime				EndTime()   const { return mTimeBoundsQueue[mTimeBoundsQueuePtr & kGeneralRingTimeBoundsQueueMask].mEndTime; }
+	void					SetTimeBounds(SampleTime startTime, SampleTime endTime);
+	
+protected:
+	Byte **					mBuffers;				// allocated in one chunk of memory
+	int						mNumberChannels;
+	UInt32					mBytesPerFrame;			// within one deinterleaved channel
+	UInt32					mCapacityFrames;		// per channel, must be a power of 2
+	UInt32					mCapacityFramesMask;
+	UInt32					mCapacityBytes;			// per channel
+	
+	// range of valid sample time in the buffer
+	typedef struct {
+		volatile SampleTime		mStartTime;
+		volatile SampleTime		mEndTime;
+		volatile UInt32			mUpdateCounter;
+	} TimeBounds;
+	
+	CARingBuffer::TimeBounds mTimeBoundsQueue[kGeneralRingTimeBoundsQueueSize];
+	UInt32 mTimeBoundsQueuePtr;
+};
+
+
+
+#endif