/* -*- c++ -*- */

/*

 * Copyright 2002,2006 Free Software Foundation, Inc.

 * 

 * This file is part of GNU Radio

 * 

 * GNU Radio 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 3, or (at your option)

 * any later version.

 * 

 * GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to

 * the Free Software Foundation, Inc., 51 Franklin Street,

 * Boston, MA 02110-1301, USA.

 */

#ifndef _GRI_AGC2_FF_H_

#define _GRI_AGC2_FF_H_

#include <gr_core_api.h>

#include <math.h>

/*!

 * \brief high performance Automatic Gain Control class with attack and decay rate

 *

 * Power is approximated by absolute value

 */

class GR_CORE_API gri_agc2_ff {

 public:

  gri_agc2_ff (float attack_rate = 1e-1, float decay_rate = 1e-2, float reference = 1.0, 

               float gain = 1.0, float max_gain = 0.0)

    : _attack_rate(attack_rate), _decay_rate(decay_rate), _reference(reference), 

      _gain(gain), _max_gain(max_gain) {};

  float attack_rate () const { return _attack_rate; }

  float decay_rate () const  { return _decay_rate; }

  float reference () const   { return _reference; }

  float gain () const              { return _gain;  }

  float max_gain () const    { return _max_gain; }

  void set_attack_rate (float rate) { _attack_rate = rate; }

  void set_decay_rate (float rate) { _decay_rate = rate; }

  void set_reference (float reference) { _reference = reference; }

  void set_gain (float gain) { _gain = gain; }

  void set_max_gain (float max_gain) { _max_gain = max_gain; }

  float scale (float input){

    float output = input * _gain;

    float tmp = (fabsf(output)) - _reference;

    float rate = _decay_rate;

    if(fabsf(tmp) > _gain)

            rate = _attack_rate;

    _gain -= tmp*rate;

#if 0

    fprintf(stdout, "rate = %f\ttmp = %f\t gain = %f\n", rate, tmp, _gain);

#endif

    // Not sure about this

    if (_gain < 0.0)

        _gain = 10e-5;

    if (_max_gain > 0.0 && _gain > _max_gain)

       _gain = _max_gain;

    return output;

  }

  void scaleN (float output[], const float input[], unsigned n){

    for (unsigned i = 0; i < n; i++)

      output[i] = scale (input[i]);

  }

 protected:

  float _attack_rate;           // attack_rate for fast changing signals

  float _decay_rate;                // decay rate for slow changing signals

  float        _reference;                // reference value

  float        _gain;                        // current gain

  float _max_gain;                // maximum gain

};

#endif /* _GRI_AGC2_FF_H_ */