/***************************************************************************
 *   Copyright (C) 2003-2005 by David Saxton                               *
 *   david@bluehaze.org                                                    *
 *                                                                         *
 *   This program 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 2 of the License, or     *
 *   (at your option) any later version.                                   *
 ***************************************************************************/

#ifndef BJT_H
#define BJT_H

#include "matrix.h"
#include "nonlinear.h"

class BJTState
{
	public:
		BJTState();
		void reset();
		
		BJTState operator-( const BJTState & s ) const;
	
		double A[3][3];
		double I[3];
};


class BJTSettings
{
	public:
		BJTSettings();
		
		double I_S; ///< saturation current
		double N_F; ///< forward emission coefficient
		double N_R; ///< reverse emission coefficient
		double B_F; ///< forward beta
		double B_R; ///< reverse beta
};


/**
@author David Saxton
*/
class BJT : public NonLinear
{
	public:
		BJT( bool isNPN );
		virtual ~BJT();
	
		virtual Type type() const { return Element_BJT; }
		virtual void update_dc();
		virtual void add_initial_dc();
		BJTSettings settings() const { return m_bjtSettings; }
		void setBJTSettings( const BJTSettings & settings );
	
	protected:
		virtual void updateCurrents();
		/**
		 * Calculates the new BJTState from the voltages on the nodes.
		 */
		void calc_eq();
		void calcIg( double V_BE, double V_BC,
					 double * I_BE, double * I_BC,
					 double * I_T,
					 double * g_BE, double * g_BC,
					 double * g_IF, double * g_IR ) const;
		void updateLim();

		BJTState m_os;
		BJTState m_ns;
		int m_pol;
		double V_BE_prev, V_BC_prev;
		double V_BE_lim, V_BC_lim;
		BJTSettings m_bjtSettings;
};

#endif
