root/trunk/ACPublic/ACSimpleCodec.cpp

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/*=============================================================================
        ACSimpleCodec.cpp

=============================================================================*/

//=============================================================================
//      Includes
//=============================================================================

#include "ACSimpleCodec.h"
#include <string.h>

//=============================================================================
//      ACSimpleCodec
//=============================================================================

static const UInt32 kBufferPad = 3840; // this is used to prevent end from passing start.

ACSimpleCodec::ACSimpleCodec(UInt32 inInputBufferByteSize)
:
        ACBaseCodec(),
        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);
        
        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::AppendInputBuffer(const void* inInputData, UInt32 inOffset, UInt32& ioInputDataByteSize)
{
        //      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;
        
        const Byte* theInputData = static_cast<const Byte*>(inInputData) + inOffset;
        
        if(ioInputDataByteSize > theAvailableByteSize) {
                ioInputDataByteSize = theAvailableByteSize;
        }
        
        //      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::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::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.
                memcpy(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;
}