clocked_object.hh

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#ifndef __SIM_CLOCKED_OBJECT_HH__
#define __SIM_CLOCKED_OBJECT_HH__


#include "params/ClockedObject.hh"
#include "sim/core.hh"
#include "sim/clock_domain.hh"
#include "sim/power_state.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;

    PowerState *powerState;
};

#endif //__SIM_CLOCKED_OBJECT_HH__