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inverse_echofilter_generic.cpp

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/*
        $Id: inverse_echofilter_generic.cpp,v 1.1 2001/03/06 15:09:26 mbn Exp $

        ------------------------------------------------------------------------
        ClanLib, the platform independent game SDK.

        This library is distributed under the GNU LIBRARY GENERAL PUBLIC LICENSE
        version 2. See COPYING for details.

        For a total list of contributers see CREDITS.

        ------------------------------------------------------------------------
*/

#ifdef WIN32
#pragma warning (disable:4786)
#endif

#include "inverse_echofilter_generic.h"
#include <memory>

CL_InverseEchoFilter::CL_InverseEchoFilter(int buffer_size)
{
        impl = new CL_InverseEchoFilter_Generic;
        impl->buffer_size = buffer_size;
        impl->pos = 0;

        impl->buffer = new int[buffer_size*2];
        memset(impl->buffer, 0, sizeof(int)*buffer_size*2);
}

CL_InverseEchoFilter::~CL_InverseEchoFilter()
{
        delete[] impl->buffer;
        delete impl;
}

void CL_InverseEchoFilter::filter(int *data, int size)
{
        int *buffer = impl->buffer;
        int &pos = impl->pos;
        int &buffer_size = impl->buffer_size;

        int delay = buffer_size / 4;
        for (int i=0; i<size*2; i++)
        {
                buffer[pos] = data[i];

                int res = 0;
                for (int j=0; j<4; j++)
                {
                        int p = pos+delay*j;
                        if (p > buffer_size) p -= buffer_size;

                        res += buffer[p]*2 / (5-j);
                }

                data[i] = res;

                pos++;
                if (pos == buffer_size) pos = 0;
        }
}

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