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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
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terms, and your use, installation, modification or redistribution of
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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
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