/* -*- Mode: Text -*-* */

/********************************************************************\
* File: sep.hs                                                       *
* Date: 11/25/1997                                                   *
* Author: Cem Unsal                                                  *
*         Robotics Institute, Carnegie-Mellon University             *
*         unsal@ri.cmu.edu                                           *
*                                                                    *
* Description:                                                       *
* Sensor Environment Processor (SEP) is part of the type Vehicle,    *
* and is used to provide:                                            *
*                                                                    *
*  (a) A subset of vehicles to be evaluated for the sensors          *
*      The output is 'current cell'; the sensor has an input         *
*      connected to this output, and the set of vehicles will be     *
*      read from the set 'Vehicles' of the current set               * 
*  (b) [Environment conditions for sensor operations]                *
*                                                                    *
* External C functions: -                                            *
*                                                                    *
*                                                                    *
* This file is distributed under the conditions described in the     *
* file 'CONDITIONS' which should accompany this file.                *
\********************************************************************/

#ifndef SAHS_SEP_HS
#define SAHS_SEP_HS

type SEP
{
  input number x, y;         // Vehicle position
  
  output Cell mycell;        // Current cell in which the vehicle travels
         
  state Vehicle myveh, sw;   // Ego-vehicle, switching vehicle

  discrete run, update;

  export cell_updated;

  transition
    run -> update {mycell:vehicle_leaving}
    // Current cell signals a vehicle is leaving
      do
      {
        sw := leavingvehicle(mycell);
      }, 

    update -> run {}
    // If leaving vehicle is not ego-vehicle, do nothing
    when sw /= myveh
      ,

    update -> run {cell_updated}
    // If leaving vehicle is ego-vehicle, update cell using global position
    when sw = myveh
      define
      {
        set(Cell) newcells := { nc : nc in NC(mycell)
                                   | x(nc) <= x and x(nc)+cs(nc) > x and
                                     y(nc) <= y and y(nc)+cs(nc) > y};
      }
      do
      {
        mycell := minel a in newcells : 1;   // Assuming the set 'newcells'
                                             // has only 1 element.
      };
}

#endif // SAHS_SEP_HS