RmsHelper.h

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/*
 * RmsHelper.h - helper class for calculating RMS
 *
 * Copyright (c) 2014 Vesa Kivimäki <contact/dot/diizy/at/nbl/dot/fi>
 * Copyright (c) 2008 Tobias Doerffel <tobydox/at/users.sourceforge.net>
 *
 * This file is part of LMMS - https://lmms.io
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program (see COPYING); if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301 USA.
 *
 */
 
#ifndef LMMS_RMS_HELPER_H
#define LMMS_RMS_HELPER_H
 
#include "lmms_math.h"
 
 
namespace lmms
{
 
 
class RmsHelper
{
public:
    RmsHelper(std::size_t size) :
        m_buffer( nullptr )
    {
        setSize( size );
    }
    virtual ~RmsHelper() 
    {
        if( m_buffer ) delete[] m_buffer;
    }
 
    void setSize(std::size_t size)
    {
        if( m_buffer )
        {
            if( m_size < size )
            {
                delete m_buffer;
                m_buffer = new float[ size ];
                m_size = size;
                reset();
            }
            else
            {
                m_size = size;
                reset();
            }
        }
        else
        {
            m_buffer = new float[ size ];
            m_size = size;
            reset();
        }
    }
 
    inline void reset()
    {
        m_sizef = 1.0f / (float) m_size;
        m_pos = 0;
        m_sum = 0.0f;
        memset( m_buffer, 0, m_size * sizeof( float ) );
    }
 
    inline float update( const float in )
    {
        m_sum -= m_buffer[ m_pos ];
        m_sum += m_buffer[ m_pos ] = in * in;
        ++m_pos %= m_size;
        return std::sqrt(m_sum * m_sizef);
    }
 
private:
    float * m_buffer;
    float m_sum;
    std::size_t m_pos;
    std::size_t m_size;
    float m_sizef;
};
 
 
} // namespace lmms
 
#endif // LMMS_RMS_HELPER_H