/* -*- 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 "Filter.h"

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

Filter::Filter( FilterConfig Config )
{
    m_ord = 0;
    m_outBuffer = NULL;
    m_inBuffer = NULL;

    initialise( Config );
}

Filter::~Filter()
{
    deInitialise();
}

void Filter::initialise( FilterConfig Config )
{
    m_ord = Config.ord;
    m_ACoeffs = Config.ACoeffs;
    m_BCoeffs = Config.BCoeffs;

    m_inBuffer = new double[ m_ord + 1 ];
    m_outBuffer = new double[ m_ord + 1 ];

    reset();
}

void Filter::deInitialise()
{
    delete[] m_inBuffer;
    delete[] m_outBuffer;
}

void Filter::reset()
{
    for( unsigned int i = 0; i < m_ord+1; i++ ){ m_inBuffer[ i ] = 0.0; }
    for(unsigned int  i = 0; i < m_ord+1; i++ ){ m_outBuffer[ i ] = 0.0; }
}

void Filter::process( double *src, double *dst, unsigned int length )
{
    unsigned int SP,i,j;

    double xin,xout;

    for (SP=0;SP<length;SP++)
    {
        xin=src[SP];
        /* move buffer */
        for ( i = 0; i < m_ord; i++) {m_inBuffer[ m_ord - i ]=m_inBuffer[ m_ord - i - 1 ];}
        m_inBuffer[0]=xin;

        xout=0.0;
        for (j=0;j< m_ord + 1; j++)
	    xout = xout + m_BCoeffs[ j ] * m_inBuffer[ j ];
        for (j = 0; j < m_ord; j++)
	    xout= xout - m_ACoeffs[ j + 1 ] * m_outBuffer[ j ];

        dst[ SP ] = xout;
        for ( i = 0; i < m_ord - 1; i++ ) { m_outBuffer[ m_ord - i - 1 ] = m_outBuffer[ m_ord - i - 2 ];}
        m_outBuffer[0]=xout;

    } /* end of SP loop */
}