cvAlign Question

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Short version: Hello, I was wondering what cvAlign does in the inner functions.

Long version: I've been looking at cvCalcOpticalFlowPyrLK code and there's a function

pyrA = cvGetMat( pyrA, &pstubA );

if( pyrA->step*pyrA->height < icvMinimalPyramidSize( imgSize ) )
    CV_Error( CV_StsBadArg, "pyramid A has insufficient size" );

which then leads to this:

static int icvMinimalPyramidSize( CvSize imgSize )
{
    return cvAlign(imgSize.width,8) * imgSize.height / 3;
}

can anyone tell me what cvAlign does (is it bit alignment)?