c@225: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
c@225: 
c@225: /*
c@225:     QM DSP Library
c@225: 
c@225:     Centre for Digital Music, Queen Mary, University of London.
c@309:     This file 2005-2006 Christian Landone.
c@309: 
c@309:     This program is free software; you can redistribute it and/or
c@309:     modify it under the terms of the GNU General Public License as
c@309:     published by the Free Software Foundation; either version 2 of the
c@309:     License, or (at your option) any later version.  See the file
c@309:     COPYING included with this distribution for more information.
c@225: */
c@225: 
c@225: #include "FiltFilt.h"
c@225: 
c@417: FiltFilt::FiltFilt(Filter::Parameters parameters) :
c@417:     m_filter(parameters)
c@225: {
c@417:     m_ord = m_filter.getOrder();
c@225: }
c@225: 
c@225: FiltFilt::~FiltFilt()
c@225: {
c@225: }
c@225: 
cannam@506: void FiltFilt::process(const double *const QM_R__ src,
cannam@506:                        double *const QM_R__ dst,
cannam@506:                        const int length)
cannam@483: {       
cannam@503:     int i;
c@225: 
c@283:     if (length == 0) return;
c@283: 
cannam@503:     int nFilt = m_ord + 1;
cannam@503:     int nFact = 3 * (nFilt - 1);
cannam@503:     int nExt = length + 2 * nFact;
c@225: 
c@417:     double *filtScratchIn = new double[ nExt ];
c@417:     double *filtScratchOut = new double[ nExt ];
cannam@483:         
cannam@503:     for (i = 0; i < nExt; i++) {
cannam@483:         filtScratchIn[ i ] = 0.0;
cannam@483:         filtScratchOut[ i ] = 0.0;
c@225:     }
c@225: 
c@225:     // Edge transients reflection
c@225:     double sample0 = 2 * src[ 0 ];
c@225:     double sampleN = 2 * src[ length - 1 ];
c@225: 
cannam@503:     int index = 0;
cannam@503:     for (i = nFact; i > 0; i--) {
cannam@506:         if (i < length) {
cannam@506:             filtScratchIn[index] = sample0 - src[ i ];
cannam@506:         }
cannam@506:         ++index;
c@225:     }
c@225:     index = 0;
cannam@503:     for (i = 0; i < nFact; i++) {
cannam@507:         if (i + 1 < length) {
cannam@506:             filtScratchIn[(nExt - nFact) + index] =
cannam@506:                 sampleN - src[ (length - 2) - i ];
cannam@506:         }
cannam@506:         ++index;
c@225:     }
c@225: 
cannam@503:     for (i = 0; i < length; i++) {
cannam@483:         filtScratchIn[ i + nFact ] = src[ i ];
c@225:     }
cannam@506:     
c@225:     ////////////////////////////////
cannam@503:     // Do 0Ph filtering
cannam@503:     m_filter.process(filtScratchIn, filtScratchOut, nExt);
cannam@483:         
c@225:     // reverse the series for FILTFILT 
cannam@503:     for (i = 0; i < nExt; i++) { 
cannam@483:         filtScratchIn[ i ] = filtScratchOut[ nExt - i - 1];
c@225:     }
c@225: 
cannam@506:     // clear filter state
cannam@506:     m_filter.reset();
cannam@506:     
c@225:     // do FILTER again 
cannam@503:     m_filter.process(filtScratchIn, filtScratchOut, nExt);
cannam@506: 
cannam@508:     // reverse the series to output
cannam@508:     for (i = 0; i < length; i++) {
cannam@508:         dst[ i ] = filtScratchOut[ nExt - nFact - i - 1 ];
c@225:     }
c@225: 
c@417:     delete [] filtScratchIn;
c@417:     delete [] filtScratchOut;
c@225: }
c@225: