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// ----------------------------------------------------------------------------
 
// Main module providing the JTAG interface: definition
 
// Copyright (C) 2009  Embecosm Limited <info@embecosm.com>
 
// Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>
 
// This file is part of the Embecosm cycle accurate SystemC JTAG library.
 
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or (at your
// option) any later version.
 
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
// License for more details.
 
// You should have received a copy of the GNU Lesser General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
// The C/C++ parts of this program are commented throughout in a fashion
// suitable for processing with Doxygen.
 
// ----------------------------------------------------------------------------
 
// $Id$
 
#ifndef JTAG_SC__H
#define JTAG_SC__H
 
#include "systemc"
#include "TapAction.h"
 
 
//! Default size of the FIFO queuing TAP actions
#define DEFAULT_TAP_FIFO_SIZE  256
 
//! The main JTAG interface module
 
//! This provides a pin interface on one side (to drive JTAG ports on a chip)
//! and a FIFO on the other, allowing the user to queue JTAG actions.
 
//! The pin interface is:
//! - sysReset (input)  The system reset. When this is asserted, the interface
//!                     will do nothing except drive TRST low.
//! - tck (input)       The JTAG clock (supplied externally)
//! - tdi (output)      Drives the TDI pin
//! - tdo (input)       Receives the TDO pin
//! - tms (output)      Drives the TMS pin
//! - trst (output)     Drives the TRST pin
 
//! @note The JTAG pins are reversed, because this module is @b driving the
//!       pins.
 
//! The FIFO allows the user to queue actions, which are of abstract type
//! TapAction::. This is subclassed to provide specific actions for reset
//! (TapActionReset::), DR-scan (TapActionDRScan::) and IR-scan
//! (TapActionIRScan::).
 
//! The size of the FIFO can optionally be specified in the constructor.
 
//! The class provides a method, sensitive to the clock, which reads actions
//! from the FIFO and processes them, issuing the requisite sequence of
//! changes of the JTAG pins until the action is complete. It then notifies
//! the action owner of completion, through an sc_event, which is part of the
//! ::TapAction class.
//! 
class JtagSC
  : public sc_core::sc_module
{
public:
 
  // The ports. Note that the naming of the low level JTAG ports is reversed,
  // because we are driving the inputs! */
  sc_core::sc_in<bool>   sysReset;	//!< The system reset (active high)
 
  sc_core::sc_in<bool>	 tck;		//!< External JTAG TCK
  sc_core::sc_out<bool>  tdi;		//!< JTAG TDI pin
  sc_core::sc_in<bool>   tdo;		//!< JTAG TDO pin
  sc_core::sc_out<bool>  tms;		//!< JTAG TMS pin
  sc_core::sc_out<bool>  trst;		//!< JTAG TRST pin
 
  //! JTAG action queue
  sc_core::sc_fifo<TapAction *> *tapActionQueue;
 
  // Constructor and destructor
  JtagSC (sc_core::sc_module_name  name,
	  int                      fifo_size = DEFAULT_TAP_FIFO_SIZE);
  ~JtagSC ();
 
 
protected:
 
  // Method to process the actions
  void  processActions();
 
 
private:
 
  //! The TAP state machine
  TapStateMachine *stateMachine;
 
  //! The next TAP action
  TapAction *currentTapAction;
 
};	// JtagSC ()
 
#endif	// JTAG_SC__H