Subversion Repositories openrisc_2011-10-31

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

// 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