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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
/*
QM DSP Library
Centre for Digital Music, Queen Mary, University of London.
This file 2005-2006 Christian Landone.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version. See the file
COPYING included with this distribution for more information.
*/
#include "FiltFilt.h"
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////
FiltFilt::FiltFilt(Filter::Parameters parameters) :
m_filter(parameters)
{
m_ord = m_filter.getOrder();
}
FiltFilt::~FiltFilt()
{
}
void FiltFilt::process(double *src, double *dst, unsigned int length)
{
unsigned int i;
if (length == 0) return;
if (length < 2) {
for( i = 0; i < length; i++ ) {
dst[i] = src [i];
}
return;
}
unsigned int nFilt = m_ord + 1;
unsigned int nFact = 3 * ( nFilt - 1);
unsigned int nExt = length + 2 * nFact;
double *filtScratchIn = new double[ nExt ];
double *filtScratchOut = new double[ nExt ];
for( i = 0; i< nExt; i++ )
{
filtScratchIn[ i ] = 0.0;
filtScratchOut[ i ] = 0.0;
}
// Edge transients reflection
double sample0 = 2 * src[ 0 ];
double sampleN = 2 * src[ length - 1 ];
unsigned int index = 0;
for( i = nFact; i > 0; i-- )
{
filtScratchIn[ index++ ] = sample0 - src[ i ];
}
index = 0;
for( i = 0; i < nFact && i + 2 < length; i++ )
{
filtScratchIn[ (nExt - nFact) + index++ ] = sampleN - src[ (length - 2) - i ];
}
for(; i < nFact; i++ )
{
filtScratchIn[ (nExt - nFact) + index++ ] = 0;
}
index = 0;
for( i = 0; i < length; i++ )
{
filtScratchIn[ i + nFact ] = src[ i ];
}
////////////////////////////////
// Do 0Ph filtering
m_filter.process( filtScratchIn, filtScratchOut, nExt);
// reverse the series for FILTFILT
for ( i = 0; i < nExt; i++)
{
filtScratchIn[ i ] = filtScratchOut[ nExt - i - 1];
}
// do FILTER again
m_filter.process( filtScratchIn, filtScratchOut, nExt);
// reverse the series back
for ( i = 0; i < nExt; i++)
{
filtScratchIn[ i ] = filtScratchOut[ nExt - i - 1 ];
}
for ( i = 0;i < nExt; i++)
{
filtScratchOut[ i ] = filtScratchIn[ i ];
}
index = 0;
for( i = 0; i < length; i++ )
{
dst[ index++ ] = filtScratchOut[ i + nFact ];
}
delete [] filtScratchIn;
delete [] filtScratchOut;
}
void FiltFilt::reset()
{
}
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