RMS.h

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/*
        dsp/RMS.h
        
        Copyright 2004 Tim Goetze <tim@quitte.de>
        
        http://quitte.de/dsp/
 
        root-mean-square accumulator.
 
*/
/*
        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; if not, write to the Free Software
        Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
        02111-1307, USA or point your web browser to http://www.gnu.org.
*/
 
#ifndef _DSP_RMS_H_
#define _DSP_RMS_H_
 
namespace DSP {
 
class RMS
{
        protected:
                sample_t buffer[64];
                int write;
 
        public:
                double sum;
 
                RMS()
                        {
                                write = 0;
                                reset();
                        }
 
                void reset()
                        {
                                sum = 0.;
                                memset (buffer, 0, sizeof (buffer));
                        }
 
                /* caution: pass in the *squared* sample value */
                void store (sample_t x)
                        {
                                sum -= buffer[write];
                                sum += (buffer[write] = x);
                                write = (write + 1) & 63;
                        }
 
                sample_t process (sample_t x)
                        {
                                store (x);
                                return rms();
                        }
 
                sample_t rms()
                        {
                                /* fabs it before sqrt, just in case ... */
                                return sqrt (fabs (sum) / 64);
                        }
};
 
} /* namespace DSP */
 
#endif /* _DSP_RMS_H_ */