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