pa_process.c

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        if( bp->hostOutputChannels[0] == 0 )
        {                                                                     
            result = paInsufficientMemory;
            goto error;
        }

        bp->hostOutputChannels[1] = &bp->hostOutputChannels[0][outputChannelCount];
    }

    PaUtil_InitializeTriangularDitherState( &bp->ditherGenerator );

    bp->samplePeriod = 1. / sampleRate;

    bp->streamCallback = streamCallback;
    bp->userData = userData;

    return result;

error:
    if( bp->tempInputBuffer )
        PaUtil_FreeMemory( bp->tempInputBuffer );

    if( bp->tempInputBufferPtrs )
        PaUtil_FreeMemory( bp->tempInputBufferPtrs );

    if( bp->hostInputChannels[0] )
        PaUtil_FreeMemory( bp->hostInputChannels[0] );

    if( bp->tempOutputBuffer )
        PaUtil_FreeMemory( bp->tempOutputBuffer );

    if( bp->tempOutputBufferPtrs )
        PaUtil_FreeMemory( bp->tempOutputBufferPtrs );

    if( bp->hostOutputChannels[0] )
        PaUtil_FreeMemory( bp->hostOutputChannels[0] );

    return result;
}


void PaUtil_TerminateBufferProcessor( PaUtilBufferProcessor* bp )
{
    if( bp->tempInputBuffer )
        PaUtil_FreeMemory( bp->tempInputBuffer );

    if( bp->tempInputBufferPtrs )
        PaUtil_FreeMemory( bp->tempInputBufferPtrs );

    if( bp->hostInputChannels[0] )
        PaUtil_FreeMemory( bp->hostInputChannels[0] );
        
    if( bp->tempOutputBuffer )
        PaUtil_FreeMemory( bp->tempOutputBuffer );

    if( bp->tempOutputBufferPtrs )
        PaUtil_FreeMemory( bp->tempOutputBufferPtrs );

    if( bp->hostOutputChannels[0] )
        PaUtil_FreeMemory( bp->hostOutputChannels[0] );
}


void PaUtil_ResetBufferProcessor( PaUtilBufferProcessor* bp )
{
    unsigned long tempInputBufferSize, tempOutputBufferSize;

    bp->framesInTempInputBuffer = bp->initialFramesInTempInputBuffer;
    bp->framesInTempOutputBuffer = bp->initialFramesInTempOutputBuffer;

    if( bp->framesInTempInputBuffer > 0 )
    {
        tempInputBufferSize =
            bp->framesPerTempBuffer * bp->bytesPerUserInputSample * bp->inputChannelCount;
        memset( bp->tempInputBuffer, 0, tempInputBufferSize );
    }

    if( bp->framesInTempOutputBuffer > 0 )
    {      
        tempOutputBufferSize =
            bp->framesPerTempBuffer * bp->bytesPerUserOutputSample * bp->outputChannelCount;
        memset( bp->tempOutputBuffer, 0, tempOutputBufferSize );
    }
}


unsigned long PaUtil_GetBufferProcessorInputLatency( PaUtilBufferProcessor* bp )
{
    return bp->initialFramesInTempInputBuffer;
}


unsigned long PaUtil_GetBufferProcessorOutputLatency( PaUtilBufferProcessor* bp )
{
    return bp->initialFramesInTempOutputBuffer;
}


void PaUtil_SetInputFrameCount( PaUtilBufferProcessor* bp,
        unsigned long frameCount )
{
    if( frameCount == 0 )
        bp->hostInputFrameCount[0] = bp->framesPerHostBuffer;
    else
        bp->hostInputFrameCount[0] = frameCount;
}
        

void PaUtil_SetNoInput( PaUtilBufferProcessor* bp )
{
    assert( bp->inputChannelCount > 0 );

    bp->hostInputChannels[0][0].data = 0;
}


void PaUtil_SetInputChannel( PaUtilBufferProcessor* bp,
        unsigned int channel, void *data, unsigned int stride )
{
    assert( channel < bp->inputChannelCount );
    
    bp->hostInputChannels[0][channel].data = data;
    bp->hostInputChannels[0][channel].stride = stride;
}


void PaUtil_SetInterleavedInputChannels( PaUtilBufferProcessor* bp,
        unsigned int firstChannel, void *data, unsigned int channelCount )
{
    unsigned int i;
    unsigned int channel = firstChannel;
    unsigned char *p = (unsigned char*)data;

    if( channelCount == 0 )
        channelCount = bp->inputChannelCount;

    assert( firstChannel < bp->inputChannelCount );
    assert( firstChannel + channelCount <= bp->inputChannelCount );

    for( i=0; i< channelCount; ++i )
    {
        bp->hostInputChannels[0][channel+i].data = p;
        p += bp->bytesPerHostInputSample;
        bp->hostInputChannels[0][channel+i].stride = channelCount;
    }
}


void PaUtil_SetNonInterleavedInputChannel( PaUtilBufferProcessor* bp,
        unsigned int channel, void *data )
{
    assert( channel < bp->inputChannelCount );
    
    bp->hostInputChannels[0][channel].data = data;
    bp->hostInputChannels[0][channel].stride = 1;
}


void PaUtil_Set2ndInputFrameCount( PaUtilBufferProcessor* bp,
        unsigned long frameCount )
{
    bp->hostInputFrameCount[1] = frameCount;
}


void PaUtil_Set2ndInputChannel( PaUtilBufferProcessor* bp,
        unsigned int channel, void *data, unsigned int stride )
{
    assert( channel < bp->inputChannelCount );

    bp->hostInputChannels[1][channel].data = data;
    bp->hostInputChannels[1][channel].stride = stride;
}


void PaUtil_Set2ndInterleavedInputChannels( PaUtilBufferProcessor* bp,
        unsigned int firstChannel, void *data, unsigned int channelCount )
{
    unsigned int i;
    unsigned int channel = firstChannel;
    unsigned char *p = (unsigned char*)data;

    if( channelCount == 0 )
        channelCount = bp->inputChannelCount;

    assert( firstChannel < bp->inputChannelCount );
    assert( firstChannel + channelCount <= bp->inputChannelCount );
    
    for( i=0; i< channelCount; ++i )
    {
        bp->hostInputChannels[1][channel+i].data = p;
        p += bp->bytesPerHostInputSample;
        bp->hostInputChannels[1][channel+i].stride = channelCount;
    }
}

        
void PaUtil_Set2ndNonInterleavedInputChannel( PaUtilBufferProcessor* bp,
        unsigned int channel, void *data )
{
    assert( channel < bp->inputChannelCount );
    
    bp->hostInputChannels[1][channel].data = data;
    bp->hostInputChannels[1][channel].stride = 1;
}


void PaUtil_SetOutputFrameCount( PaUtilBufferProcessor* bp,
        unsigned long frameCount )
{
    if( frameCount == 0 )
        bp->hostOutputFrameCount[0] = bp->framesPerHostBuffer;
    else
        bp->hostOutputFrameCount[0] = frameCount;
}


void PaUtil_SetOutputChannel( PaUtilBufferProcessor* bp,
        unsigned int channel, void *data, unsigned int stride )
{
    assert( channel < bp->outputChannelCount );
    
    bp->hostOutputChannels[0][channel].data = data;
    bp->hostOutputChannels[0][channel].stride = stride;
}


void PaUtil_SetInterleavedOutputChannels( PaUtilBufferProcessor* bp,
        unsigned int firstChannel, void *data, unsigned int channelCount )
{
    unsigned int i;
    unsigned int channel = firstChannel;
    unsigned char *p = (unsigned char*)data;

    if( channelCount == 0 )
        channelCount = bp->outputChannelCount;

    assert( firstChannel < bp->outputChannelCount );
    assert( firstChannel + channelCount <= bp->outputChannelCount );
    
    for( i=0; i< channelCount; ++i )
    {
        bp->hostOutputChannels[0][channel+i].data = p;
        p += bp->bytesPerHostOutputSample;
        bp->hostOutputChannels[0][channel+i].stride = channelCount;
    }
}


void PaUtil_SetNonInterleavedOutputChannel( PaUtilBufferProcessor* bp,
        unsigned int channel, void *data )
{
    assert( channel < bp->outputChannelCount );

    bp->hostOutputChannels[0][channel].data = data;
    bp->hostOutputChannels[0][channel].stride = 1;
}


void PaUtil_Set2ndOutputFrameCount( PaUtilBufferProcessor* bp,
        unsigned long frameCount )
{
    bp->hostOutputFrameCount[1] = frameCount;
}


void PaUtil_Set2ndOutputChannel( PaUtilBufferProcessor* bp,
        unsigned int channel, void *data, unsigned int stride )
{
    assert( channel < bp->outputChannelCount );

    bp->hostOutputChannels[1][channel].data = data;
    bp->hostOutputChannels[1][channel].stride = stride;
}


void PaUtil_Set2ndInterleavedOutputChannels( PaUtilBufferProcessor* bp,
        unsigned int firstChannel, void *data, unsigned int channelCount )
{
    unsigned int i;
    unsigned int channel = firstChannel;
    unsigned char *p = (unsigned char*)data;

    if( channelCount == 0 )
        channelCount = bp->outputChannelCount;

    assert( firstChannel < bp->outputChannelCount );
    assert( firstChannel + channelCount <= bp->outputChannelCount );
    
    for( i=0; i< channelCount; ++i )
    {
        bp->hostOutputChannels[1][channel+i].data = p;
        p += bp->bytesPerHostOutputSample;
        bp->hostOutputChannels[1][channel+i].stride = channelCount;
    }
}

        
void PaUtil_Set2ndNonInterleavedOutputChannel( PaUtilBufferProcessor* bp,
        unsigned int channel, void *data )
{
    assert( channel < bp->outputChannelCount );
    
    bp->hostOutputChannels[1][channel].data = data;
    bp->hostOutputChannels[1][channel].stride = 1;
}


void PaUtil_BeginBufferProcessing( PaUtilBufferProcessor* bp,
        PaStreamCallbackTimeInfo* timeInfo, PaStreamCallbackFlags callbackStatusFlags )
{
    bp->timeInfo = timeInfo;

    /* the first streamCallback will be called to process samples which are
        currently in the input buffer before the ones starting at the timeInfo time */
        
    bp->timeInfo->inputBufferAdcTime -= bp->framesInTempInputBuffer * bp->samplePeriod;
    
    bp->timeInfo->currentTime = 0; /** FIXME: @todo time info currentTime not implemented */

    /* the first streamCallback will be called to generate samples which will be
        outputted after the frames currently in the output buffer have been
        outputted. */
    bp->timeInfo->outputBufferDacTime += bp->framesInTempOutputBuffer * bp->samplePeriod;

    bp->callbackStatusFlags = callbackStatusFlags;

    bp->hostInputFrameCount[1] = 0;
    bp->hostOutputFrameCount[1] = 0;
}


/*
    NonAdaptingProcess() is a simple buffer copying adaptor that can handle
    both full and half duplex copies. It processes framesToProcess frames,
    broken into blocks bp->framesPerTempBuffer long.
    This routine can be used when the streamCallback doesn't care what length
    the buffers are, or when framesToProcess is an integer multiple of
    bp->framesPerTempBuffer, in which case streamCallback will always be called
    with bp->framesPerTempBuffer samples.
*/
static unsigned long NonAdaptingProcess( PaUtilBufferProcessor *bp,