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// ----------------------------------------------------------------------------

// The TAP state machine: 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/>.

// ----------------------------------------------------------------------------

// $Id$

#ifndef TAP_STATE_MACHINE__H

#define TAP_STATE_MACHINE__H

//! Enumeration of all the states in the TAP state machine.

//! Last entry is not a state, but a marker of the number of states. Useful

//! for state transition matrices.

enum TapState {

  TAP_TEST_LOGIC_RESET =  0,

  TAP_RUN_TEST_IDLE    =  1,

  TAP_SELECT_DR_SCAN   =  2,

  TAP_CAPTURE_DR       =  3,

  TAP_SHIFT_DR         =  4,

  TAP_EXIT1_DR         =  5,

  TAP_PAUSE_DR         =  6,

  TAP_EXIT2_DR         =  7,

  TAP_UPDATE_DR        =  8,

  TAP_SELECT_IR_SCAN   =  9,

  TAP_CAPTURE_IR       = 10,

  TAP_SHIFT_IR         = 11,

  TAP_EXIT1_IR         = 12,

  TAP_PAUSE_IR         = 13,

  TAP_EXIT2_IR         = 14,

  TAP_UPDATE_IR        = 15,

  TAP_SIZE             = 16

};      // enum TapState

//! Textual representation of all the TAP states.

//! Provided for debugging purposes

static const char *tapStateNames[TAP_SIZE] = {

  "Test-Logic-Reset",

  "Run-Test/Idle",

  "Select-DR-Scan",

  "Capture-DR",

  "Shift-DR",

  "Exit1-DR",

  "Pause-DR",

  "Exit2-DR",

  "Update-DR",

  "Select-IR-Scan",

  "Capture-IR",

  "Shift-IR",

  "Exit1-IR",

  "Pause-IR",

  "Exit2-IR",

  "Update-IR"

};      // tapStateNames

//! TAP state machine

//! Tracks the state of the TAP. This should mirror the state of the TAP in

//! the connected HW.

//! The state machine is created in the reset condition, but in truth we

//! cannot know what the state is. It is essential the TAP is reset before

//! first being used.

//! We cannot know for certain when the TAP state machine has been reset. 5

//! consecutive TMS=1 transitions will take you there, but a reset of the

//! target could undo this. It is the responsibility of the user of the TAP

//! state machine.

//! For convenience of users, this class provides a flag (resetDone::),

//! with accessors by which reset state can be recorded.

class TapStateMachine

{

public:

  friend class  JtagSC;

  friend class  TapAction;

  friend class  TapActionDRScan;

  friend class  TapActionIRScan;

  friend class  TapActionReset;

protected:

  //! The number of cycles of TMS=1 required to force reset

  static const int TAP_RESET_CYCLES = 5;

  // Constructor

  TapStateMachine();

  // Accessor for TAP state

  TapState  getState ();

  // Accessors for TAP reset state

  bool  getResetDone ();

  void  setResetDone (bool  _resetState);

  // Drive the TAP state machine

  void  nextState (bool tms);

  // Determine if we are in a particular target state

  bool  targetState (TapState  target,

                     bool     &tms);

private:

  //! The current TAP state

  TapState  state;

  //! True if the TAP state machine has been through a reset.

  //! The state can be sure to match that of the target. Responsibility of

  //! user classes to set this.

  bool  resetDone;

};      // class TapStateMachine

#endif  // TAP_STATE_MACHINE__H