text: /****************************************************************************
   *
   *   Copyright (C) 2012 PX4 Development Team. All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   * 3. Neither the name PX4 nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
   * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   ****************************************************************************/
  
  /**
   * @file blocks.h
   *
   * Controller library code
   */
  
  #pragma once
  
  #include <px4_defines.h>
  #include <assert.h>
  #include <time.h>
  #include <stdlib.h>
  #include <math.h>
  #include <float.h>
  #include <mathlib/math/test/test.hpp>
  #include <mathlib/math/filter/LowPassFilter2p.hpp>
  
  #include "block/Block.hpp"
  #include "block/BlockParam.hpp"
  
  #include "matrix/math.hpp"
  
  namespace control
  {
  
  /**
   * A low pass filter as described here:
   * http://en.wikipedia.org/wiki/Low-pass_filter.
   */
  class __EXPORT BlockLowPass : public Block
  {
  public:
  // methods
  	BlockLowPass(SuperBlock *parent, const char *name) :
  		Block(parent, name),
  		_state(NAN /* initialize to invalid val, force into is_finite() check on first call */),
  		_fCut(this, "") // only one parameter, no need to name
  	{}
  	virtual ~BlockLowPass() {}
  	float update(float input);
  // accessors
  	float getState() { return _state; }
  	float getFCut() { return _fCut.get(); }
  	void setState(float state) { _state = state; }
  protected:
  // attributes
  	float _state;
  	control::BlockParamFloat _fCut;
  };
  
  } // namespace control
  