/*

     File: ACSimpleCodec.cpp 

 Abstract:  ACSimpleCodec.h  

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*/

//=============================================================================

//  Includes

//=============================================================================

#include "ACSimpleCodec.h"

#include <string.h>

//=============================================================================

//  ACSimpleCodec

//=============================================================================

static const UInt32 kBufferPad = 64; // this is used to prevent end from passing start.

ACSimpleCodec::ACSimpleCodec(UInt32 inInputBufferByteSize, AudioComponentInstance inInstance)

:

    ACBaseCodec(inInstance),

    mInputBuffer(NULL),

    mInputBufferByteSize(inInputBufferByteSize+kBufferPad),

    mInputBufferStart(0),

    mInputBufferEnd(0)

{

}

ACSimpleCodec::~ACSimpleCodec()

{

    delete[] mInputBuffer;

}

void    ACSimpleCodec::Initialize(const AudioStreamBasicDescription* inInputFormat, const AudioStreamBasicDescription* inOutputFormat, const void* inMagicCookie, UInt32 inMagicCookieByteSize)

{

    ReallocateInputBuffer(mInputBufferByteSize - kBufferPad);

    // By definition CBR has this greater than 0. We must avoid a div by 0 error in AppendInputData()

    // Note this will cause us to fail initialization which is intended

    if (mInputFormat.mBytesPerPacket == 0)

    {

        CODEC_THROW(kAudioCodecUnsupportedFormatError);

    }   

    ACBaseCodec::Initialize(inInputFormat, inOutputFormat, inMagicCookie, inMagicCookieByteSize);

}

void    ACSimpleCodec::Uninitialize()

{

    //  get rid of the buffer

    delete[] mInputBuffer;

    mInputBuffer = NULL;

    //  reset the ring buffer state

    mInputBufferStart = 0;

    mInputBufferEnd = 0;

    ACBaseCodec::Uninitialize();

}

void    ACSimpleCodec::Reset()

{

    //  clear the entire input buffer

    if (mInputBuffer) { // could be called before allocated.

        memset(mInputBuffer, 0, mInputBufferByteSize);

    }

    //  reset the ring buffer state

    mInputBufferStart = 0;

    mInputBufferEnd = 0;

    ACBaseCodec::Reset();

}

UInt32  ACSimpleCodec::GetInputBufferByteSize() const

{

    return mInputBufferByteSize - kBufferPad; // minus kBufferPad to prevent end moving past start

}

UInt32  ACSimpleCodec::GetUsedInputBufferByteSize() const

{

    UInt32 theAnswer = 0;

    //  this object uses a ring buffer

    if(mInputBufferStart <= mInputBufferEnd)

    {

        //  the active region is contiguous

        theAnswer = mInputBufferEnd - mInputBufferStart;

    }

    else

    {

        //  the active region wraps around 

        theAnswer = (mInputBufferByteSize - mInputBufferStart) + mInputBufferEnd;

    }

    return theAnswer;

}

void    ACSimpleCodec::AppendInputData(const void* inInputData, UInt32& ioInputDataByteSize, UInt32& ioNumberPackets, const AudioStreamPacketDescription* inPacketDescription)

{

    //  this buffer handling code doesn't care about such things as the packet descriptions

    if(!mIsInitialized) CODEC_THROW(kAudioCodecStateError);

    //  this is a ring buffer we're dealing with, so we need to set up a few things

    UInt32 theUsedByteSize = GetUsedInputBufferByteSize();

    UInt32 theAvailableByteSize = GetInputBufferByteSize() - theUsedByteSize;

    UInt32 theMaxAvailableInputBytes = ioInputDataByteSize; // we can't consume more than we get

    const Byte* theInputData = static_cast<const Byte*>(inInputData);

    // >>jamesmcc: added this because ioNumberPackets was not being updated if less was taken than given.

    // THIS ASSUMES CBR!

    UInt32 bytesPerPacketOfInput = mInputFormat.mBytesPerPacket;

    UInt32 theAvailablePacketSize = theAvailableByteSize / bytesPerPacketOfInput;

    UInt32 minPacketSize = ioNumberPackets < theAvailablePacketSize ? ioNumberPackets : theAvailablePacketSize;

    UInt32 minByteSize = minPacketSize * bytesPerPacketOfInput;

    //  we can copy only as much data as there is or up to how much space is availiable

    ioNumberPackets = minPacketSize;

    ioInputDataByteSize = minByteSize;

    // ioInputDataByteSize had better be <= to theMaxAvailableInputBytes or we're screwed

    if (ioInputDataByteSize > theMaxAvailableInputBytes)

    {

        CODEC_THROW(kAudioCodecStateError);

    }

    // <<jamesmcc 

    //  now we have to copy the data taking into account the wrap around and where the start is

    if(mInputBufferEnd + ioInputDataByteSize < mInputBufferByteSize)

    {

        //  no wrap around here

        memcpy(mInputBuffer + mInputBufferEnd, theInputData, ioInputDataByteSize);

        //  adjust the end point

        mInputBufferEnd += ioInputDataByteSize;

    }

    else

    {

        //  the copy will wrap

        //  copy the first part

        UInt32 theBeforeWrapByteSize = mInputBufferByteSize - mInputBufferEnd;

        memcpy(mInputBuffer + mInputBufferEnd, theInputData, theBeforeWrapByteSize);

        //  and the rest

        UInt32 theAfterWrapByteSize = ioInputDataByteSize - theBeforeWrapByteSize;

        memcpy(mInputBuffer, theInputData + theBeforeWrapByteSize, theAfterWrapByteSize);

        //  adjust the end point

        mInputBufferEnd = theAfterWrapByteSize;

    }

}

void    ACSimpleCodec::ZeroPadInputData(UInt32& ioNumberPackets, const AudioStreamPacketDescription* inPacketDescription)

{

    //  this buffer handling code doesn't care about such things as the packet descriptions

    if(!mIsInitialized) CODEC_THROW(kAudioCodecStateError);

    //  this is a ring buffer we're dealing with, so we need to set up a few things

    UInt32 theUsedByteSize = GetUsedInputBufferByteSize();

    UInt32 theAvailableByteSize = GetInputBufferByteSize() - theUsedByteSize;

    // >>jamesmcc: added this because ioNumberPackets was not being updated if less was taken than given.

    // THIS ASSUMES CBR!

    UInt32 bytesPerPacketOfInput = mInputFormat.mBytesPerPacket;

    UInt32 theAvailablePacketSize = theAvailableByteSize / bytesPerPacketOfInput;

    UInt32 minPacketSize = ioNumberPackets < theAvailablePacketSize ? ioNumberPackets : theAvailablePacketSize;

    UInt32 minByteSize = minPacketSize * bytesPerPacketOfInput;

    //  we can copy only as much data as there is or up to how much space is availiable

    ioNumberPackets = minPacketSize;

    // <<jamesmcc 

    //  now we have to copy the data taking into account the wrap around and where the start is

    if(mInputBufferEnd + minByteSize < mInputBufferByteSize)

    {

        //  no wrap around here

        memset(mInputBuffer + mInputBufferEnd, 0, minByteSize);

        //  adjust the end point

        mInputBufferEnd += minByteSize;

    }

    else

    {

        //  the copy will wrap

        //  copy the first part

        UInt32 theBeforeWrapByteSize = mInputBufferByteSize - mInputBufferEnd;

        memset(mInputBuffer + mInputBufferEnd, 0, theBeforeWrapByteSize);

        //  and the rest

        UInt32 theAfterWrapByteSize = minByteSize - theBeforeWrapByteSize;

        memset(mInputBuffer, 0, theAfterWrapByteSize);

        //  adjust the end point

        mInputBufferEnd = theAfterWrapByteSize;

    }

}

void    ACSimpleCodec::ConsumeInputData(UInt32 inConsumedByteSize)

{

    //  this is a convenience routine to make maintaining the ring buffer state easy

    UInt32 theContiguousRange = GetInputBufferContiguousByteSize();

    if(inConsumedByteSize > GetUsedInputBufferByteSize()) CODEC_THROW(kAudioCodecUnspecifiedError);

    if(inConsumedByteSize <= theContiguousRange)

    {

        //  the region to consume doesn't wrap

        //  figure out how much to consume

        inConsumedByteSize = (theContiguousRange < inConsumedByteSize) ? theContiguousRange : inConsumedByteSize;

        //  clear the consumed bits

        memset(mInputBuffer + mInputBufferStart, 0, inConsumedByteSize);

        //  adjust the start

        mInputBufferStart += inConsumedByteSize;

    }

    else

    {

        //  the region to consume will wrap

        //  clear the bits to the end of the buffer

        memset(mInputBuffer + mInputBufferStart, 0, theContiguousRange);

        //  now clear the bits left from the start

        memset(mInputBuffer, 0, inConsumedByteSize - theContiguousRange);

        //  adjust the start

        mInputBufferStart = inConsumedByteSize - theContiguousRange;

    }

}

Byte* ACSimpleCodec::GetBytes(UInt32& ioNumberBytes) const

{

    // if a client's algorithm has to have contiguous data and mInputBuffer wraps, then someone has to make a copy.

    // I can do it more efficiently than the client. 

    if(!mIsInitialized) CODEC_THROW(kAudioCodecStateError);

    UInt32 theUsedByteSize = GetUsedInputBufferByteSize();

    //UInt32 theAvailableByteSize = GetInputBufferByteSize() - theUsedByteSize;

    if (ioNumberBytes > theUsedByteSize) ioNumberBytes = theUsedByteSize;

    SInt32 leftOver = mInputBufferStart + ioNumberBytes - mInputBufferByteSize;

    if(leftOver > 0)

    {

        // need to copy beginning of buffer to the end. 

        // We cleverly over allocated our buffer space to make this possible.

        memmove(mInputBuffer + mInputBufferByteSize, mInputBuffer, leftOver);

    }

    return GetInputBufferStart();

}

void    ACSimpleCodec::ReallocateInputBuffer(UInt32 inInputBufferByteSize)

{

    mInputBufferByteSize = inInputBufferByteSize + kBufferPad;

    //  toss the old buffer

    delete[] mInputBuffer;

    mInputBuffer = NULL;

    //  allocate the new one

    // allocate extra in order to allow making contiguous data.

    UInt32 allocSize = 2*inInputBufferByteSize + kBufferPad;

    mInputBuffer = new Byte[allocSize];

    memset(mInputBuffer, 0, allocSize);

    //  reset the ring buffer state

    mInputBufferStart = 0;

    mInputBufferEnd = 0;

}

void    ACSimpleCodec::GetPropertyInfo(AudioCodecPropertyID inPropertyID, UInt32& outPropertyDataSize, Boolean& outWritable)

{

    switch(inPropertyID)

    {

        case kAudioCodecPropertyInputBufferSize:

            outPropertyDataSize = SizeOf32(UInt32);

            outWritable = true;

            break;

        default:

            ACBaseCodec::GetPropertyInfo(inPropertyID, outPropertyDataSize, outWritable);

            break;

    }

}

void    ACSimpleCodec::SetProperty(AudioCodecPropertyID inPropertyID, UInt32 inPropertyDataSize, const void* inPropertyData)

{

    switch(inPropertyID)

    {

        case kAudioCodecPropertyInputBufferSize:

            if(inPropertyDataSize == sizeof(UInt32))

            {

                ReallocateInputBuffer(*reinterpret_cast<const UInt32*>(inPropertyData));

            }

            else

            {

                CODEC_THROW(kAudioCodecBadPropertySizeError);

            }

            break;

        default:

            ACBaseCodec::SetProperty(inPropertyID, inPropertyDataSize, inPropertyData);

            break;            

    }

}