clocked_object.hh

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/*
 * Copyright (c) 2012-2013, 2015-2016 ARM Limited
 * Copyright (c) 2013 Cornell University
 * All rights reserved
 *
 * The license below extends only to copyright in the software and shall
 * not be construed as granting a license to any other intellectual
 * property including but not limited to intellectual property relating
 * to a hardware implementation of the functionality of the software
 * licensed hereunder.  You may use the software subject to the license
 * terms below provided that you ensure that this notice is replicated
 * unmodified and in its entirety in all distributions of the software,
 * modified or unmodified, in source code or in binary form.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Andreas Hansson
 *          Christopher Torng
 *          Akash Bagdia
 *          David Guillen Fandos
 */

#ifndef __SIM_CLOCKED_OBJECT_HH__
#define __SIM_CLOCKED_OBJECT_HH__

#include "base/callback.hh"
#include "base/intmath.hh"
#include "enums/PwrState.hh"
#include "params/ClockedObject.hh"
#include "sim/core.hh"
#include "sim/clock_domain.hh"
#include "sim/sim_object.hh"

class Clocked
{

  private:
    // the tick value of the next clock edge (>= curTick()) at the
    // time of the last call to update()
    mutable Tick tick;

    // The cycle counter value corresponding to the current value of
    // 'tick'
    mutable Cycles cycle;

    void
    update() const
    {
        // both tick and cycle are up-to-date and we are done, note
        // that the >= is important as it captures cases where tick
        // has already passed curTick()
        if (tick >= curTick())
            return;

        // optimise for the common case and see if the tick should be
        // advanced by a single clock period
        tick += clockPeriod();
        ++cycle;

        // see if we are done at this point
        if (tick >= curTick())
            return;

        // if not, we have to recalculate the cycle and tick, we
        // perform the calculations in terms of relative cycles to
        // allow changes to the clock period in the future
        Cycles elapsedCycles(divCeil(curTick() - tick, clockPeriod()));
        cycle += elapsedCycles;
        tick += elapsedCycles * clockPeriod();
    }

    ClockDomain &clockDomain;

  protected:

    Clocked(ClockDomain &clk_domain)
        : tick(0), cycle(0), clockDomain(clk_domain)
    {
        // Register with the clock domain, so that if the clock domain
        // frequency changes, we can update this object's tick.
        clockDomain.registerWithClockDomain(this);
    }

    Clocked(Clocked &) = delete;
    Clocked &operator=(Clocked &) = delete;

    virtual ~Clocked() { }

    void
    resetClock() const
    {
        Cycles elapsedCycles(divCeil(curTick(), clockPeriod()));
        cycle = elapsedCycles;
        tick = elapsedCycles * clockPeriod();
    }

    virtual void clockPeriodUpdated() {}

  public:

    void
    updateClockPeriod()
    {
        update();
        clockPeriodUpdated();
    }

    Tick
    clockEdge(Cycles cycles=Cycles(0)) const
    {
        // align tick to the next clock edge
        update();

        // figure out when this future cycle is
        return tick + clockPeriod() * cycles;
    }

    Cycles
    curCycle() const
    {
        // align cycle to the next clock edge.
        update();

        return cycle;
    }

    Tick nextCycle() const { return clockEdge(Cycles(1)); }

    uint64_t frequency() const { return SimClock::Frequency / clockPeriod(); }

    Tick clockPeriod() const { return clockDomain.clockPeriod(); }

    double voltage() const { return clockDomain.voltage(); }

    Cycles
    ticksToCycles(Tick t) const
    {
        return Cycles(divCeil(t, clockPeriod()));
    }

    Tick cyclesToTicks(Cycles c) const { return clockPeriod() * c; }
};

class ClockedObject : public SimObject, public Clocked
{
  public:
    ClockedObject(const ClockedObjectParams *p);

    typedef ClockedObjectParams Params;
    const Params *
    params() const
    {
        return reinterpret_cast<const Params*>(_params);
    }

    void serialize(CheckpointOut &cp) const override;
    void unserialize(CheckpointIn &cp) override;

    Enums::PwrState pwrState() const { return _currPwrState; }

    std::string
    pwrStateName() const
    {
        return Enums::PwrStateStrings[_currPwrState];
    }

    std::vector<double> pwrStateWeights() const;

    void computeStats();

    void pwrState(Enums::PwrState);

  protected:

    Enums::PwrState _currPwrState;

    Tick prvEvalTick;

    struct ClockedObjectStats : public Stats::Group
    {
        ClockedObjectStats(ClockedObject &co);

        void regStats() override;
        void preDumpStats() override;

        ClockedObject &clockedObject;
        Stats::Scalar numPwrStateTransitions;
        Stats::Distribution pwrStateClkGateDist;
        Stats::Vector pwrStateResidencyTicks;
    } stats;
};

#endif //__SIM_CLOCKED_OBJECT_HH__