/*

     File: CARingBuffer.h 

 Abstract:  Part of CoreAudio Utility Classes  

  Version: 1.2.2 

 Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple 

 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 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) 2013 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