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"
 
namespace gem5
{
 
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 sim_clock::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);
 
    using Params = ClockedObjectParams;
 
    void serialize(CheckpointOut &cp) const override;
    void unserialize(CheckpointIn &cp) override;
 
    PowerState *powerState;
};
 
} // namespace gem5
 
#endif //__SIM_CLOCKED_OBJECT_HH__