AUOutputBL.cpp

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#include "AUOutputBL.h"
#if !defined(__COREAUDIO_USE_FLAT_INCLUDES__)
    #include <AudioUnit/AUComponent.h>
#else
    #include <AUComponent.h>
#endif
/*
struct AudioBufferList
{
    UInt32      mNumberBuffers;
    AudioBuffer mBuffers[1];
};
struct AudioBuffer
{
    UInt32  mNumberChannels;    //  number of interleaved channels in the buffer
    UInt32  mDataByteSize;      //  the size of the buffer pointed to by mData
    void*   mData;              //  the pointer to the buffer
};
*/

AUOutputBL::AUOutputBL (const CAStreamBasicDescription &inDesc, UInt32 inDefaultNumFrames) 
        : mFormat (inDesc),
          mBufferMemory(NULL),
          mBufferList (NULL),
          mNumberBuffers (0), // keep this here, so can ensure integrity of ABL
          mBufferSize (0),
          mFrames(inDefaultNumFrames)
{
    mNumberBuffers = mFormat.IsInterleaved() ? 1 : mFormat.NumberChannels();
    mBufferList = reinterpret_cast<AudioBufferList*>(new Byte[offsetof(AudioBufferList, mBuffers) + (mNumberBuffers * sizeof(AudioBuffer))]);
}

AUOutputBL::~AUOutputBL()
{
    if (mBufferMemory)
        delete[] mBufferMemory;

    if (mBufferList)
        delete [] (Byte *)mBufferList;
}

void    AUOutputBL::Prepare (UInt32 inNumFrames, bool inWantNullBufferIfAllocated) 
{
    UInt32 channelsPerBuffer = mFormat.IsInterleaved() ? mFormat.NumberChannels() : 1;
    
    if (mBufferMemory == NULL || inWantNullBufferIfAllocated)
    {
        mBufferList->mNumberBuffers = mNumberBuffers;
        AudioBuffer *buf = &mBufferList->mBuffers[0];
        for (UInt32 i = 0; i < mNumberBuffers; ++i, ++buf) {
            buf->mNumberChannels = channelsPerBuffer;
            buf->mDataByteSize = mFormat.FramesToBytes (inNumFrames);
            buf->mData = NULL;
        }
    }
    else
    {
        UInt32 nBytes = mFormat.FramesToBytes (inNumFrames);
        if ((nBytes * mNumberBuffers) > AllocatedBytes())
            throw OSStatus(kAudioUnitErr_TooManyFramesToProcess);
            
        mBufferList->mNumberBuffers = mNumberBuffers;
        AudioBuffer *buf = &mBufferList->mBuffers[0];
        Byte* p = mBufferMemory;
        for (UInt32 i = 0; i < mNumberBuffers; ++i, ++buf) {
            buf->mNumberChannels = channelsPerBuffer;
            buf->mDataByteSize = nBytes;
            buf->mData = p;
            p += mBufferSize;
        }
    }
}


void    AUOutputBL::Allocate (UInt32 inNumFrames)
{
    if (inNumFrames) 
    {
        UInt32 nBytes = mFormat.FramesToBytes (inNumFrames);
        
        if (nBytes <= AllocatedBytes()) 
            return;
        
            // align successive buffers for Altivec and to take alternating
            // cache line hits by spacing them by odd multiples of 16
        if (mNumberBuffers > 1)
            nBytes = (nBytes + (0x10 - (nBytes & 0xF))) | 0x10;
        
        mBufferSize = nBytes;
        
        UInt32 memorySize = mBufferSize * mNumberBuffers;
        Byte *newMemory = new Byte[memorySize];
        memset(newMemory, 0, memorySize);   // make buffer "hot"
        
        Byte *oldMemory = mBufferMemory;
        mBufferMemory = newMemory;
        delete[] oldMemory;
        
        mFrames = inNumFrames;
    } 
    else 
    {
        if (mBufferMemory) {
            delete [] mBufferMemory;
            mBufferMemory = NULL;
        }
        mBufferSize = 0;
        mFrames = 0;
    }
}

#if DEBUG
void            AUOutputBL::Print()
{
    printf ("AUOutputBL::Print\n");
    mFormat.Print();
    printf ("Num Buffers:%d, mFrames:%d, allocatedMemory:%c\n", (int)mBufferList->mNumberBuffers, (int)mFrames, (mBufferMemory != NULL ? 'T' : 'F'));
    AudioBuffer *buf = &mBufferList->mBuffers[0];
    for (UInt32 i = 0; i < mBufferList->mNumberBuffers; ++i, ++buf)
        printf ("\tBuffer:%d, Size:%d, Chans:%d, Buffer:%p\n", (int)i, (int)buf->mDataByteSize, (int)buf->mNumberChannels, buf->mData);
}
#endif