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/**
 * @author Aaron Berk
 *
 * @section LICENSE
 *
 * Copyright (c) 2010 ARM Limited
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * @section DESCRIPTION
 * 
 * A PID controller is a widely used feedback controller commonly found in
 * industry.
 *
 * This library is a port of Brett Beauregard's Arduino PID library:
 *
 *  http://www.arduino.cc/playground/Code/PIDLibrary
 *
 * The wikipedia article on PID controllers is a good place to start on
 * understanding how they work:
 *
 *  http://en.wikipedia.org/wiki/PID_controller
 *
 * For a clear and elegant explanation of how to implement and tune a
 * controller, the controlguru website by Douglas J. Cooper (who also happened
 * to be Brett's controls professor) is an excellent reference:
 *
 *  http://www.controlguru.com/
 */

/**
 * Includes
 */
#include "mbed.h"

class PID
{


  public:

  //Constants used in some of the functions below
  #define AUTOMATIC 1
  #define MANUAL  0
  #define DIRECT  0
  #define REVERSE  1

    
  //commonly used functions **************************************************************************
    PID(double*, double*, double*,        // * constructor.  links the PID to the Input, Output, and 
        double, double, double, int, float*, float*);     //   Setpoint.  Initial tuning parameters are also set here
  
    void SetMode(int Mode);               // * sets PID to either Manual (0) or Auto (non-0)

    double Compute(float*);                       // * performs the PID calculation.  it should be
                                          //   called every time loop() cycles. ON/OFF and
                                          //   calculation frequency can be set using SetMode
                                          //   SetSampleTime respectively

    void SetOutputLimits(double, double); //clamps the output to a specific range. 0-255 by default, but
                      //it's likely the user will want to change this depending on
                      //the application
  


  //available but not commonly used functions ********************************************************
    void SetTunings(double, double,       // * While most users will set the tunings once in the 
                    double);            //   constructor, this function gives the user the option
                                          //   of changing tunings during runtime for Adaptive control
  void SetControllerDirection(int);   // * Sets the Direction, or "Action" of the controller. DIRECT
                      //   means the output will increase when error is positive. REVERSE
                      //   means the opposite.  it's very unlikely that this will be needed
                      //   once it is set in the constructor.
    void SetSampleTime(int);              // * sets the frequency, in Milliseconds, with which 
                                          //   the PID calculation is performed.  default is 100
                      
                      
                      
  //Display functions ****************************************************************
  double GetKp();             // These functions query the pid for interal values.
  double GetKi();             //  they were created mainly for the pid front-end,
  double GetKd();             // where it's important to know what is actually 
  int GetMode();              //  inside the PID.
  int GetDirection();           //

  private:
  void Initialize();
  
  double dispKp;        // * we'll hold on to the tuning parameters in user-entered 
  double dispKi;        //   format for display purposes
  double dispKd;        //
    
  double kp;                  // * (P)roportional Tuning Parameter
    double ki;                  // * (I)ntegral Tuning Parameter
    double kd;                  // * (D)erivative Tuning Parameter

  int controllerDirection;

    double *myInput;              // * Pointers to the Input, Output, and Setpoint variables
    double *myOutput;             //   This creates a hard link between the variables and the 
    double *mySetpoint;           //   PID, freeing the user from having to constantly tell us
                                  //   what these values are.  with pointers we'll just know.
        
  float lastTime;
  double ITerm, lastInput;

  float SampleTime;
  double outMin, outMax;
  bool inAuto;
};