libs/qm-dsp/dsp/signalconditioning/Filter.cpp

   1 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
   2
   3 /*
   4     QM DSP Library
   5
   6     Centre for Digital Music, Queen Mary, University of London.
   7     This file 2005-2006 Christian Landone.
   8
   9     This program is free software; you can redistribute it and/or
  10     modify it under the terms of the GNU General Public License as
  11     published by the Free Software Foundation; either version 2 of the
  12     License, or (at your option) any later version.  See the file
  13     COPYING included with this distribution for more information.
  14 */
  15
  16 #include "Filter.h"
  17
  18 //////////////////////////////////////////////////////////////////////
  19 // Construction/Destruction
  20 //////////////////////////////////////////////////////////////////////
  21
  22 Filter::Filter( FilterConfig Config )
  23 {
  24     m_ord = 0;
  25     m_outBuffer = NULL;
  26     m_inBuffer = NULL;
  27
  28     initialise( Config );
  29 }
  30
  31 Filter::~Filter()
  32 {
  33     deInitialise();
  34 }
  35
  36 void Filter::initialise( FilterConfig Config )
  37 {
  38     m_ord = Config.ord;
  39     m_ACoeffs = Config.ACoeffs;
  40     m_BCoeffs = Config.BCoeffs;
  41
  42     m_inBuffer = new double[ m_ord + 1 ];
  43     m_outBuffer = new double[ m_ord + 1 ];
  44
  45     reset();
  46 }
  47
  48 void Filter::deInitialise()
  49 {
  50     delete[] m_inBuffer;
  51     delete[] m_outBuffer;
  52 }
  53
  54 void Filter::reset()
  55 {
  56     for( unsigned int i = 0; i < m_ord+1; i++ ){ m_inBuffer[ i ] = 0.0; }
  57     for(unsigned int  i = 0; i < m_ord+1; i++ ){ m_outBuffer[ i ] = 0.0; }
  58 }
  59
  60 void Filter::process( double *src, double *dst, unsigned int length )
  61 {
  62     unsigned int SP,i,j;
  63
  64     double xin,xout;
  65
  66     for (SP=0;SP<length;SP++)
  67     {
  68         xin=src[SP];
  69         /* move buffer */
  70         for ( i = 0; i < m_ord; i++) {m_inBuffer[ m_ord - i ]=m_inBuffer[ m_ord - i - 1 ];}
  71         m_inBuffer[0]=xin;
  72
  73         xout=0.0;
  74         for (j=0;j< m_ord + 1; j++)
  75             xout = xout + m_BCoeffs[ j ] * m_inBuffer[ j ];
  76         for (j = 0; j < m_ord; j++)
  77             xout= xout - m_ACoeffs[ j + 1 ] * m_outBuffer[ j ];
  78
  79         dst[ SP ] = xout;
  80         for ( i = 0; i < m_ord - 1; i++ ) { m_outBuffer[ m_ord - i - 1 ] = m_outBuffer[ m_ord - i - 2 ];}
  81         m_outBuffer[0]=xout;
  82
  83     } /* end of SP loop */
  84 }
  85
  86
  87