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[/] [openrisc/] [trunk/] [orpsocv2/] [bench/] [sysc/] [src/] [TapActionIRScan.cpp] - Blame information for rev 197

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// ----------------------------------------------------------------------------
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// TAP IR-Scan action: implementation
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// Copyright (C) 2009  Embecosm Limited <info@embecosm.com>
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// Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>
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// This file is part of the Embecosm cycle accurate SystemC JTAG library.
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// This program is free software: you can redistribute it and/or modify it
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// under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or (at your
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// option) any later version.
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// This program is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
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// License for more details.
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// You should have received a copy of the GNU Lesser General Public License
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// along with this program.  If not, see <http://www.gnu.org/licenses/>.
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// The C/C++ parts of this program are commented throughout in a fashion
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// suitable for processing with Doxygen.
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// ----------------------------------------------------------------------------
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// $Id$
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#include "TapActionIRScan.h"
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#include "TapStateMachine.h"
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//! Constructor
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//! Sets up the superclass with the SystemC completion event and initializes
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//! our state as appropriate.
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//! @param[in] doneEvent  SystemC event to be signalled when this action is
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//!                       complete.
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//! @param[in] _iRegIn    The register to shift in.
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//! @param[in] _iRegSize  Size in bits of the register to shift in.
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TapActionIRScan::TapActionIRScan (sc_core::sc_event *_doneEvent,
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                                  uint32_t           _iRegIn,
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                                  int                _iRegSize) :
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  TapAction (_doneEvent),
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  iRegIn (_iRegIn),
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  iRegSize (_iRegSize),
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  iRegOut (0),
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  bitsShifted (0),
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  iRScanState (SHIFT_IR_PREPARING)
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{
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}       // TapActionIRScan ()
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//! Process the Shift-IR action
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//! This drives the IR-Scan state. We can only do this if we have the TAP
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//! state machine in a consistent state, which in turn is only possible if we
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//! have been through a reset cycle.
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//! If the state machine shows it has yet to be through a reset cycle, we
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//! drive that cycle, after issuing a warning. This functionality is provided
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//! by the parent class, TapAction::.
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//! @param[in]  tapStateMachine  The TAP state machine with which this action
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//!                              is associated. 
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//! @param[out] tdi              The value to drive on TDI
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//! @param[in]  tdo              The value currently on TDO
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//! @param[out] tms              The value to drive on TMS
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//! @return  True if the action is complete
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bool
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TapActionIRScan::process (TapStateMachine *tapStateMachine,
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                          bool            &tdi,
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                          bool             tdo,
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                          bool            &tms)
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{
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  // Ensure we are in a consistent state. If not then we'll have moved towards
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  // it and can return with the given tms
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  if (!checkResetDone (tapStateMachine, tms, true))
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    {
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      return false;
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    }
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  // We are consistent, so work through the IR-Scan process
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  switch (iRScanState)
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    {
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    case SHIFT_IR_PREPARING:
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      // Are we in the Shift-IR state yet?
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      if (!tapStateMachine->targetState (TAP_SHIFT_IR, tms))
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        {
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          return  false;                // Not there. Accept the TMS value
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        }
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      else
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        {
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          iRScanState = SHIFT_IR_SHIFTING;      // Drop through
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        }
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    case SHIFT_IR_SHIFTING:
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      // Are we still shifting stuff?
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      if (bitsShifted < iRegSize)
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        {
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          // We are in the Shift-IR state. Another bit about to be done, so
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          // increment the count
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          bitsShifted++;
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          // Shift out the TDI value from the bottom of the register
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          tdi       = iRegIn & 1;
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          iRegIn >>= 1;
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          // Record the TDO value. This is always a cycle late, so we ignore
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          // it the first time. The value shifts in from the top.
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          if (bitsShifted > 1)
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            {
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              iRegOut >>= 1;            // Move all the existing bits right
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              if (tdo)                  // OR any new bit in
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                {
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                  uint32_t tmpBit = 1 << (iRegSize - 1);
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                  iRegOut |= tmpBit;
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                }
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            }
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          // TMS is 0 to keep us here UNLESS this is the last bit, in which
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          // case it is 1 to move us into Exit1-IR.
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          tms = (bitsShifted == iRegSize);
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          return false;
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        }
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      else
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        {
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          // Capture the last TDO bit
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          iRegOut >>= 1;                // Move all the existing bits right
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          if (tdo)                      // OR any new bit in
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            {
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              uint32_t tmpBit = 1 << (iRegSize - 1);
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              iRegOut |= tmpBit;
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            }
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          iRScanState = SHIFT_IR_UPDATING;      // Drop through
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        }
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    case SHIFT_IR_UPDATING:
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      // Are we still trying to update?
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      if (!tapStateMachine->targetState (TAP_UPDATE_IR, tms))
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        {
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          return  false;                // Not there. Accept the TMS value
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        }
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      else
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        {
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          return  true;                 // All done
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        }
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    }
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}       // process ()
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//! Get the shifted out register
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//! @return  The value of the shifted our register
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uint32_t
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TapActionIRScan::getIRegOut ()
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{
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  return  iRegOut;
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}       // getIRegOut ()
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