dither.h

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#ifndef CONTROL_TOOLBOX__DITHER_H
#define CONTROL_TOOLBOX__DITHER_H

#include <cstdlib>
#include <ctime>
#include <math.h>
#include <ros/ros.h>

namespace control_toolbox {

/***************************************************/
class Dither
{
public:

  Dither();

  ~Dither();

  double update();

   /*
   *\brief Dither gets an amplitude, must be >0 to initialize
   *
   *\param amplitude Amplitude of white noise output
   *\param seed Random seed for white noise
   */
  bool init(const double &amplitude, const double &seed)
  {
    if (amplitude < 0.0)
    {
      ROS_ERROR("Dither amplitude not set properly. Amplitude must be >0.");
      return false;
    }
    
    amplitude_ = amplitude;

    // Somewhat mimics the old code.  A given seed gives a
    // reproducible sequence of random numbers, and that's what
    // matters.
    unsigned long s = (unsigned long)seed;
    seed_[0] = (s) ^ 45213;
    seed_[1] = (s >> 16) ^ 39204;
    seed_[2] = (s >> 32) ^ 5598;
    
    return true;
  }


private:
  double amplitude_;   
  double saved_value_;
  bool has_saved_value_;
  double s_;
  double x_;
  unsigned short seed_[3];
};
}

#endif