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@225:     This file copyright 2005-2006 Christian Landone.
c@225:     All rights reserved.
c@225: */
c@225: 
c@225: #include "Decimator.h"
c@225: 
c@225: //////////////////////////////////////////////////////////////////////
c@225: // Construction/Destruction
c@225: //////////////////////////////////////////////////////////////////////
c@225: 
c@225: Decimator::Decimator( unsigned int inLength, unsigned int decFactor )
c@225: {
c@225: 
c@225:     m_inputLength = 0;
c@225:     m_outputLength = 0;
c@225:     m_decFactor = 1;
c@225: 
c@225:     initialise( inLength, decFactor );
c@225: }
c@225: 
c@225: Decimator::~Decimator()
c@225: {
c@225:     deInitialise();
c@225: }
c@225: 
c@225: void Decimator::initialise( unsigned int inLength, unsigned int decFactor)
c@225: {
c@225:     m_inputLength = inLength;
c@225:     m_decFactor = decFactor;
c@225:     m_outputLength = m_inputLength / m_decFactor;
c@225: 
c@225:     decBuffer = new double[ m_inputLength ];
c@225: 
c@225:     if( m_decFactor == 4 )
c@225:     {
c@225: 	//////////////////////////////////////////////////
c@225: 	b[ 0 ] = 0.10133306904918619;
c@225: 	b[ 1 ] = -0.2447523353702363;
c@225: 	b[ 2 ] = 0.33622528590120965;
c@225: 	b[ 3 ] = -0.13936581560633518;
c@225: 	b[ 4 ] = -0.13936581560633382;
c@225: 	b[ 5 ] = 0.3362252859012087;
c@225: 	b[ 6 ] = -0.2447523353702358;
c@225: 	b[ 7 ] = 0.10133306904918594;
c@225: 
c@225: 	a[ 0 ] = 1;
c@225: 	a[ 1 ] = -3.9035590278139427;
c@225: 	a[ 2 ] = 7.5299379980621133;
c@225: 	a[ 3 ] = -8.6890803793177511;
c@225: 	a[ 4 ] = 6.4578667096099176;
c@225: 	a[ 5 ] = -3.0242979431223631;
c@225: 	a[ 6 ] = 0.83043385136748382;
c@225: 	a[ 7 ] = -0.094420800837809335;
c@225: 	//////////////////////////////////////////////////
c@225:     }
c@225:     else if( m_decFactor == 2 )
c@225:     {
c@225: 	//////////////////////////////////////////////////
c@225: 	b[ 0 ] = 0.20898944260075727;
c@225: 	b[ 1 ] = 0.40011234879814367;
c@225: 	b[ 2 ] = 0.819741973072733;
c@225: 	b[ 3 ] = 1.0087419911682323;
c@225: 	b[ 4 ] = 1.0087419911682325;
c@225: 	b[ 5 ] = 0.81974197307273156;
c@225: 	b[ 6 ] = 0.40011234879814295;
c@225: 	b[ 7 ] = 0.20898944260075661;
c@225: 
c@225: 	a[ 0 ] = 1;
c@225: 	a[ 1 ] = 0.0077331184208358217;
c@225: 	a[ 2 ] = 1.9853971155964376;
c@225: 	a[ 3 ] = 0.19296739275341004;
c@225: 	a[ 4 ] = 1.2330748872852182;
c@225: 	a[ 5 ] = 0.18705341389316466;
c@225: 	a[ 6 ] = 0.23659265908013868;
c@225: 	a[ 7 ] = 0.032352924250533946;
c@225:     }
c@225:     else
c@225:     {
c@225: 	//////////////////////////////////////////////////
c@225: 	b[ 0 ] = 1;
c@225: 	b[ 1 ] = 0;
c@225: 	b[ 2 ] = 0;
c@225: 	b[ 3 ] = 0;
c@225: 	b[ 4 ] = 0;
c@225: 	b[ 5 ] = 0;
c@225: 	b[ 6 ] = 0;
c@225: 	b[ 7 ] = 0;
c@225: 
c@225: 	a[ 0 ] = 1;
c@225: 	a[ 1 ] = 0;
c@225: 	a[ 2 ] = 0;
c@225: 	a[ 3 ] = 0;
c@225: 	a[ 4 ] = 0;
c@225: 	a[ 5 ] = 0;
c@225: 	a[ 6 ] = 0;
c@225: 	a[ 7 ] = 0;
c@225:     }
c@225: 
c@225:     resetFilter();
c@225: }
c@225: 
c@225: void Decimator::deInitialise()
c@225: {
c@225:     delete [] decBuffer;
c@225: }
c@225: 
c@225: void Decimator::resetFilter()
c@225: {
c@225:     Input = Output = 0;
c@225: 
c@225:     o1=o2=o3=o4=o5=o6=o7=0;
c@225: }
c@225: 
c@225: void Decimator::doAntiAlias(double *src, double *dst, unsigned int length)
c@225: {
c@225: 
c@225:     for( unsigned int i = 0; i < length; i++ )
c@225:     {
c@225: 	Input = (double)src[ i ];
c@225: 
c@225: 	Output = Input * b[ 0 ] + o1;
c@225: 
c@225: 	o1 = Input * b[ 1 ] - Output * a[ 1 ] + o2;
c@225: 	o2 = Input * b[ 2 ] - Output * a[ 2 ] + o3;
c@225: 	o3 = Input * b[ 3 ] - Output * a[ 3 ] + o4;
c@225: 	o4 = Input * b[ 4 ] - Output * a[ 4 ] + o5;
c@225: 	o5 = Input * b[ 5 ] - Output * a[ 5 ] + o6;
c@225: 	o6 = Input * b[ 6 ] - Output * a[ 6 ] + o7;
c@225: 	o7 = Input * b[ 7 ] - Output * a[ 7 ] ;
c@225: 
c@225: 	dst[ i ] = Output;
c@225:     }
c@225: 
c@225: }
c@225: 
c@225: void Decimator::process(double *src, double *dst)
c@225: {
c@225:     if( m_decFactor != 1 )
c@225:     {
c@225: 	doAntiAlias( src, decBuffer, m_inputLength );
c@225:     }
c@225:     unsigned idx = 0;
c@225: 
c@225:     for( unsigned int i = 0; i < m_outputLength; i++ )
c@225:     {
c@225: 	dst[ idx++ ] = decBuffer[ m_decFactor * i ];
c@225:     }
c@225: }