src/sim/eventq.hh - arm/gem5 - Git at Google

 /*
  * Copyright (c) 2000-2005 The Regents of The University of Michigan
  * All rights reserved.
  *
  * 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
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * Authors: Steve Reinhardt
  *          Nathan Binkert
  */

 /* @file
  * EventQueue interfaces
  */

 #ifndef __SIM_EVENTQ_HH__
 #define __SIM_EVENTQ_HH__

 #include <algorithm>
 #include <cassert>
 #include <climits>
 #include <iosfwd>
 #include <string>

 #include "base/flags.hh"
 #include "base/misc.hh"
 #include "base/trace.hh"
 #include "base/types.hh"
 #include "debug/Event.hh"
 #include "sim/serialize.hh"

 class EventQueue;       // forward declaration

 extern EventQueue mainEventQueue;

 /*
  * An item on an event queue.  The action caused by a given
  * event is specified by deriving a subclass and overriding the
  * process() member function.
  *
  * Caution, the order of members is chosen to maximize data packing.
  */
 class Event : public Serializable
 {
     friend class EventQueue;

   protected:
     typedef unsigned short FlagsType;
     typedef ::Flags<FlagsType> Flags;

     static const FlagsType PublicRead    = 0x003f; // public readable flags
     static const FlagsType PublicWrite   = 0x001d; // public writable flags
     static const FlagsType Squashed      = 0x0001; // has been squashed
     static const FlagsType Scheduled     = 0x0002; // has been scheduled
     static const FlagsType AutoDelete    = 0x0004; // delete after dispatch
     static const FlagsType AutoSerialize = 0x0008; // must be serialized
     static const FlagsType IsExitEvent   = 0x0010; // special exit event
     static const FlagsType IsMainQueue   = 0x0020; // on main event queue
     static const FlagsType Initialized   = 0x7a40; // somewhat random bits
     static const FlagsType InitMask      = 0xffc0; // mask for init bits

     bool
     initialized() const
     {
         return this && (flags & InitMask) == Initialized;
     }

   public:
     typedef int8_t Priority;

   private:
     // The event queue is now a linked list of linked lists.  The
     // 'nextBin' pointer is to find the bin, where a bin is defined as
     // when+priority.  All events in the same bin will be stored in a
     // second linked list (a stack) maintained by the 'nextInBin'
     // pointer.  The list will be accessed in LIFO order.  The end
     // result is that the insert/removal in 'nextBin' is
     // linear/constant, and the lookup/removal in 'nextInBin' is
     // constant/constant.  Hopefully this is a significant improvement
     // over the current fully linear insertion.
     Event *nextBin;
     Event *nextInBin;

     static Event *insertBefore(Event *event, Event *curr);
     static Event *removeItem(Event *event, Event *last);

     Tick _when;         //!< timestamp when event should be processed
     Priority _priority; //!< event priority
     Flags flags;

 #ifndef NDEBUG
     /// Global counter to generate unique IDs for Event instances
     static Counter instanceCounter;

     /// This event's unique ID.  We can also use pointer values for
     /// this but they're not consistent across runs making debugging
     /// more difficult.  Thus we use a global counter value when
     /// debugging.
     Counter instance;

     /// queue to which this event belongs (though it may or may not be
     /// scheduled on this queue yet)
     EventQueue *queue;
 #endif

 #ifdef EVENTQ_DEBUG
     Tick whenCreated;   //!< time created
     Tick whenScheduled; //!< time scheduled
 #endif

     void
     setWhen(Tick when, EventQueue *q)
     {
         _when = when;
 #ifndef NDEBUG
         queue = q;
 #endif
 #ifdef EVENTQ_DEBUG
         whenScheduled = curTick();
 #endif
     }

   protected:
     /// Accessor for flags.
     Flags
     getFlags() const
     {
         return flags & PublicRead;
     }

     bool
     isFlagSet(Flags _flags) const
     {
         assert(_flags.noneSet(~PublicRead));
         return flags.isSet(_flags);
     }

     /// Accessor for flags.
     void
     setFlags(Flags _flags)
     {
         assert(_flags.noneSet(~PublicWrite));
         flags.set(_flags);
     }

     void
     clearFlags(Flags _flags)
     {
         assert(_flags.noneSet(~PublicWrite));
         flags.clear(_flags);
     }

     void
     clearFlags()
     {
         flags.clear(PublicWrite);
     }

     // This function isn't really useful if TRACING_ON is not defined
     virtual void trace(const char *action);     //!< trace event activity

   public:
     /// Event priorities, to provide tie-breakers for events scheduled
     /// at the same cycle.  Most events are scheduled at the default
     /// priority; these values are used to control events that need to
     /// be ordered within a cycle.

     /// Minimum priority
     static const Priority Minimum_Pri =          SCHAR_MIN;

     /// If we enable tracing on a particular cycle, do that as the
     /// very first thing so we don't miss any of the events on
     /// that cycle (even if we enter the debugger).
     static const Priority Trace_Enable_Pri =          -101;

     /// Breakpoints should happen before anything else (except
     /// enabling trace output), so we don't miss any action when
     /// debugging.
     static const Priority Debug_Break_Pri =           -100;

     /// CPU switches schedule the new CPU's tick event for the
     /// same cycle (after unscheduling the old CPU's tick event).
     /// The switch needs to come before any tick events to make
     /// sure we don't tick both CPUs in the same cycle.
     static const Priority CPU_Switch_Pri =             -31;

     /// For some reason "delayed" inter-cluster writebacks are
     /// scheduled before regular writebacks (which have default
     /// priority).  Steve?
     static const Priority Delayed_Writeback_Pri =       -1;

     /// Default is zero for historical reasons.
     static const Priority Default_Pri =                  0;

     /// Serailization needs to occur before tick events also, so
     /// that a serialize/unserialize is identical to an on-line
     /// CPU switch.
     static const Priority Serialize_Pri =               32;

     /// CPU ticks must come after other associated CPU events
     /// (such as writebacks).
     static const Priority CPU_Tick_Pri =                50;

     /// Statistics events (dump, reset, etc.) come after
     /// everything else, but before exit.
     static const Priority Stat_Event_Pri =              90;

     /// Progress events come at the end.
     static const Priority Progress_Event_Pri =          95;

     /// If we want to exit on this cycle, it's the very last thing
     /// we do.
     static const Priority Sim_Exit_Pri =               100;

     /// Maximum priority
     static const Priority Maximum_Pri =          SCHAR_MAX;

     /*
      * Event constructor
      * @param queue that the event gets scheduled on
      */
     Event(Priority p = Default_Pri, Flags f = 0)
         : nextBin(NULL), nextInBin(NULL), _priority(p),
           flags(Initialized | f)
     {
         assert(f.noneSet(~PublicWrite));
 #ifndef NDEBUG
         instance = ++instanceCounter;
         queue = NULL;
 #endif
 #ifdef EVENTQ_DEBUG
         whenCreated = curTick();
         whenScheduled = 0;
 #endif
     }

     virtual ~Event();
     virtual const std::string name() const;

     /// Return a C string describing the event.  This string should
     /// *not* be dynamically allocated; just a const char array
     /// describing the event class.
     virtual const char *description() const;

     /// Dump the current event data
     void dump() const;

   public:
     /*
      * This member function is invoked when the event is processed
      * (occurs).  There is no default implementation; each subclass
      * must provide its own implementation.  The event is not
      * automatically deleted after it is processed (to allow for
      * statically allocated event objects).
      *
      * If the AutoDestroy flag is set, the object is deleted once it
      * is processed.
      */
     virtual void process() = 0;

     /// Determine if the current event is scheduled
     bool scheduled() const { return flags.isSet(Scheduled); }

     /// Squash the current event
     void squash() { flags.set(Squashed); }

     /// Check whether the event is squashed
     bool squashed() const { return flags.isSet(Squashed); }

     /// See if this is a SimExitEvent (without resorting to RTTI)
     bool isExitEvent() const { return flags.isSet(IsExitEvent); }

     /// Get the time that the event is scheduled
     Tick when() const { return _when; }

     /// Get the event priority
     Priority priority() const { return _priority; }

 #ifndef SWIG
     struct priority_compare
         : public std::binary_function<Event *, Event *, bool>
     {
         bool
         operator()(const Event *l, const Event *r) const
         {
             return l->when() >= r->when() || l->priority() >= r->priority();
         }
     };

     virtual void serialize(std::ostream &os);
     virtual void unserialize(Checkpoint *cp, const std::string &section);
 #endif
 };

 #ifndef SWIG
 inline bool
 operator<(const Event &l, const Event &r)
 {
     return l.when() < r.when() ||
         (l.when() == r.when() && l.priority() < r.priority());
 }

 inline bool
 operator>(const Event &l, const Event &r)
 {
     return l.when() > r.when() ||
         (l.when() == r.when() && l.priority() > r.priority());
 }

 inline bool
 operator<=(const Event &l, const Event &r)
 {
     return l.when() < r.when() ||
         (l.when() == r.when() && l.priority() <= r.priority());
 }
 inline bool
 operator>=(const Event &l, const Event &r)
 {
     return l.when() > r.when() ||
         (l.when() == r.when() && l.priority() >= r.priority());
 }

 inline bool
 operator==(const Event &l, const Event &r)
 {
     return l.when() == r.when() && l.priority() == r.priority();
 }

 inline bool
 operator!=(const Event &l, const Event &r)
 {
     return l.when() != r.when() || l.priority() != r.priority();
 }
 #endif

 /*
  * Queue of events sorted in time order
  */
 class EventQueue : public Serializable
 {
   private:
     std::string objName;
     Event *head;

     void insert(Event *event);
     void remove(Event *event);

     EventQueue(const EventQueue &);
     const EventQueue &operator=(const EventQueue &);

   public:
     EventQueue(const std::string &n);

     virtual const std::string name() const { return objName; }

     // schedule the given event on this queue
     void schedule(Event *event, Tick when);
     void deschedule(Event *event);
     void reschedule(Event *event, Tick when, bool always = false);

     Tick nextTick() const { return head->when(); }
     Event *serviceOne();

     // process all events up to the given timestamp.  we inline a
     // quick test to see if there are any events to process; if so,
     // call the internal out-of-line version to process them all.
     void
     serviceEvents(Tick when)
     {
         while (!empty()) {
             if (nextTick() > when)
                 break;

             /**
              * @todo this assert is a good bug catcher.  I need to
              * make it true again.
              */
             //assert(head->when() >= when && "event scheduled in the past");
             serviceOne();
         }
     }

     // return true if no events are queued
     bool empty() const { return head == NULL; }

     void dump() const;

     bool debugVerify() const;

     /**
      *  function for replacing the head of the event queue, so that a
      *  different set of events can run without disturbing events that have
      *  already been scheduled. Already scheduled events can be processed
      *  by replacing the original head back.
      *  USING THIS FUNCTION CAN BE DANGEROUS TO THE HEALTH OF THE SIMULATOR.
      *  NOT RECOMMENDED FOR USE.
      */
     Event* replaceHead(Event* s);

 #ifndef SWIG
     virtual void serialize(std::ostream &os);
     virtual void unserialize(Checkpoint *cp, const std::string &section);
 #endif
 };

 #ifndef SWIG
 class EventManager
 {
   protected:
     /** A pointer to this object's event queue */
     EventQueue *eventq;

   public:
     EventManager(EventManager &em) : eventq(em.queue()) {}
     EventManager(EventManager *em) : eventq(em ? em->queue() : NULL) {}
     EventManager(EventQueue *eq) : eventq(eq) {}

     EventQueue *
     queue() const
     {
         return eventq;
     }

     operator EventQueue *() const
     {
         return eventq;
     }

     void
     schedule(Event &event, Tick when)
     {
         eventq->schedule(&event, when);
     }

     void
     deschedule(Event &event)
     {
         eventq->deschedule(&event);
     }

     void
     reschedule(Event &event, Tick when, bool always = false)
     {
         eventq->reschedule(&event, when, always);
     }

     void
     schedule(Event *event, Tick when)
     {
         eventq->schedule(event, when);
     }

     void
     deschedule(Event *event)
     {
         eventq->deschedule(event);
     }

     void
     reschedule(Event *event, Tick when, bool always = false)
     {
         eventq->reschedule(event, when, always);
     }
 };

 inline void
 EventQueue::schedule(Event *event, Tick when)
 {
     // Typecasting Tick->Utick here since gcc
     // complains about signed overflow
     assert((UTick)when >= (UTick)curTick());
     assert(!event->scheduled());
     assert(event->initialized());

     event->setWhen(when, this);
     insert(event);
     event->flags.set(Event::Scheduled);
     if (this == &mainEventQueue)
         event->flags.set(Event::IsMainQueue);
     else
         event->flags.clear(Event::IsMainQueue);

     if (DTRACE(Event))
         event->trace("scheduled");
 }

 inline void
 EventQueue::deschedule(Event *event)
 {
     assert(event->scheduled());
     assert(event->initialized());

     remove(event);

     event->flags.clear(Event::Squashed);
     event->flags.clear(Event::Scheduled);

     if (DTRACE(Event))
         event->trace("descheduled");

     if (event->flags.isSet(Event::AutoDelete))
         delete event;
 }

 inline void
 EventQueue::reschedule(Event *event, Tick when, bool always)
 {
     // Typecasting Tick->Utick here since gcc
     // complains about signed overflow
     assert((UTick)when >= (UTick)curTick());
     assert(always || event->scheduled());
     assert(event->initialized());

     if (event->scheduled())
         remove(event);

     event->setWhen(when, this);
     insert(event);
     event->flags.clear(Event::Squashed);
     event->flags.set(Event::Scheduled);
     if (this == &mainEventQueue)
         event->flags.set(Event::IsMainQueue);
     else
         event->flags.clear(Event::IsMainQueue);

     if (DTRACE(Event))
         event->trace("rescheduled");
 }

 template <class T, void (T::* F)()>
 void
 DelayFunction(EventQueue *eventq, Tick when, T *object)
 {
     class DelayEvent : public Event
     {
       private:
         T *object;

       public:
         DelayEvent(T *o)
             : Event(Default_Pri, AutoDelete), object(o)
         { }
         void process() { (object->*F)(); }
         const char *description() const { return "delay"; }
     };

     eventq->schedule(new DelayEvent(object), when);
 }

 template <class T, void (T::* F)()>
 class EventWrapper : public Event
 {
   private:
     T *object;

   public:
     EventWrapper(T *obj, bool del = false, Priority p = Default_Pri)
         : Event(p), object(obj)
     {
         if (del)
             setFlags(AutoDelete);
     }

     EventWrapper(T &obj, bool del = false, Priority p = Default_Pri)
         : Event(p), object(&obj)
     {
         if (del)
             setFlags(AutoDelete);
     }

     void process() { (object->*F)(); }

     const std::string
     name() const
     {
         return object->name() + ".wrapped_event";
     }

     const char *description() const { return "EventWrapped"; }
 };
 #endif

 #endif // __SIM_EVENTQ_HH__
	/*
	* Copyright (c) 2000-2005 The Regents of The University of Michigan
	* All rights reserved.
	*
	* 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
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	* Authors: Steve Reinhardt
	* Nathan Binkert
	*/

	/* @file
	* EventQueue interfaces
	*/

	#ifndef __SIM_EVENTQ_HH__
	#define __SIM_EVENTQ_HH__

	#include <algorithm>
	#include <cassert>
	#include <climits>
	#include <iosfwd>
	#include <string>

	#include "base/flags.hh"
	#include "base/misc.hh"
	#include "base/trace.hh"
	#include "base/types.hh"
	#include "debug/Event.hh"
	#include "sim/serialize.hh"

	class EventQueue; // forward declaration

	extern EventQueue mainEventQueue;

	/*
	* An item on an event queue. The action caused by a given
	* event is specified by deriving a subclass and overriding the
	* process() member function.
	*
	* Caution, the order of members is chosen to maximize data packing.
	*/
	class Event : public Serializable
	{
	friend class EventQueue;

	protected:
	typedef unsigned short FlagsType;
	typedef ::Flags<FlagsType> Flags;

	static const FlagsType PublicRead = 0x003f; // public readable flags
	static const FlagsType PublicWrite = 0x001d; // public writable flags
	static const FlagsType Squashed = 0x0001; // has been squashed
	static const FlagsType Scheduled = 0x0002; // has been scheduled
	static const FlagsType AutoDelete = 0x0004; // delete after dispatch
	static const FlagsType AutoSerialize = 0x0008; // must be serialized
	static const FlagsType IsExitEvent = 0x0010; // special exit event
	static const FlagsType IsMainQueue = 0x0020; // on main event queue
	static const FlagsType Initialized = 0x7a40; // somewhat random bits
	static const FlagsType InitMask = 0xffc0; // mask for init bits

	bool
	initialized() const
	{
	return this && (flags & InitMask) == Initialized;
	}

	public:
	typedef int8_t Priority;

	private:
	// The event queue is now a linked list of linked lists. The
	// 'nextBin' pointer is to find the bin, where a bin is defined as
	// when+priority. All events in the same bin will be stored in a
	// second linked list (a stack) maintained by the 'nextInBin'
	// pointer. The list will be accessed in LIFO order. The end
	// result is that the insert/removal in 'nextBin' is
	// linear/constant, and the lookup/removal in 'nextInBin' is
	// constant/constant. Hopefully this is a significant improvement
	// over the current fully linear insertion.
	Event *nextBin;
	Event *nextInBin;

	static Event insertBefore(Event event, Event *curr);
	static Event removeItem(Event event, Event *last);

	Tick _when; //!< timestamp when event should be processed
	Priority _priority; //!< event priority
	Flags flags;

	#ifndef NDEBUG
	/// Global counter to generate unique IDs for Event instances
	static Counter instanceCounter;

	/// This event's unique ID. We can also use pointer values for
	/// this but they're not consistent across runs making debugging
	/// more difficult. Thus we use a global counter value when
	/// debugging.
	Counter instance;

	/// queue to which this event belongs (though it may or may not be
	/// scheduled on this queue yet)
	EventQueue *queue;
	#endif

	#ifdef EVENTQ_DEBUG
	Tick whenCreated; //!< time created
	Tick whenScheduled; //!< time scheduled
	#endif

	void
	setWhen(Tick when, EventQueue *q)
	{
	_when = when;
	#ifndef NDEBUG
	queue = q;
	#endif
	#ifdef EVENTQ_DEBUG
	whenScheduled = curTick();
	#endif
	}

	protected:
	/// Accessor for flags.
	Flags
	getFlags() const
	{
	return flags & PublicRead;
	}

	bool
	isFlagSet(Flags _flags) const
	{
	assert(_flags.noneSet(~PublicRead));
	return flags.isSet(_flags);
	}

	/// Accessor for flags.
	void
	setFlags(Flags _flags)
	{
	assert(_flags.noneSet(~PublicWrite));
	flags.set(_flags);
	}

	void
	clearFlags(Flags _flags)
	{
	assert(_flags.noneSet(~PublicWrite));
	flags.clear(_flags);
	}

	void
	clearFlags()
	{
	flags.clear(PublicWrite);
	}

	// This function isn't really useful if TRACING_ON is not defined
	virtual void trace(const char *action); //!< trace event activity

	public:
	/// Event priorities, to provide tie-breakers for events scheduled
	/// at the same cycle. Most events are scheduled at the default
	/// priority; these values are used to control events that need to
	/// be ordered within a cycle.

	/// Minimum priority
	static const Priority Minimum_Pri = SCHAR_MIN;

	/// If we enable tracing on a particular cycle, do that as the
	/// very first thing so we don't miss any of the events on
	/// that cycle (even if we enter the debugger).
	static const Priority Trace_Enable_Pri = -101;

	/// Breakpoints should happen before anything else (except
	/// enabling trace output), so we don't miss any action when
	/// debugging.
	static const Priority Debug_Break_Pri = -100;

	/// CPU switches schedule the new CPU's tick event for the
	/// same cycle (after unscheduling the old CPU's tick event).
	/// The switch needs to come before any tick events to make
	/// sure we don't tick both CPUs in the same cycle.
	static const Priority CPU_Switch_Pri = -31;

	/// For some reason "delayed" inter-cluster writebacks are
	/// scheduled before regular writebacks (which have default
	/// priority). Steve?
	static const Priority Delayed_Writeback_Pri = -1;

	/// Default is zero for historical reasons.
	static const Priority Default_Pri = 0;

	/// Serailization needs to occur before tick events also, so
	/// that a serialize/unserialize is identical to an on-line
	/// CPU switch.
	static const Priority Serialize_Pri = 32;

	/// CPU ticks must come after other associated CPU events
	/// (such as writebacks).
	static const Priority CPU_Tick_Pri = 50;

	/// Statistics events (dump, reset, etc.) come after
	/// everything else, but before exit.
	static const Priority Stat_Event_Pri = 90;

	/// Progress events come at the end.
	static const Priority Progress_Event_Pri = 95;

	/// If we want to exit on this cycle, it's the very last thing
	/// we do.
	static const Priority Sim_Exit_Pri = 100;

	/// Maximum priority
	static const Priority Maximum_Pri = SCHAR_MAX;

	/*
	* Event constructor
	* @param queue that the event gets scheduled on
	*/
	Event(Priority p = Default_Pri, Flags f = 0)
	: nextBin(NULL), nextInBin(NULL), _priority(p),
	flags(Initialized \| f)
	{
	assert(f.noneSet(~PublicWrite));
	#ifndef NDEBUG
	instance = ++instanceCounter;
	queue = NULL;
	#endif
	#ifdef EVENTQ_DEBUG
	whenCreated = curTick();
	whenScheduled = 0;
	#endif
	}

	virtual ~Event();
	virtual const std::string name() const;

	/// Return a C string describing the event. This string should
	/// not be dynamically allocated; just a const char array
	/// describing the event class.
	virtual const char *description() const;

	/// Dump the current event data
	void dump() const;

	public:
	/*
	* This member function is invoked when the event is processed
	* (occurs). There is no default implementation; each subclass
	* must provide its own implementation. The event is not
	* automatically deleted after it is processed (to allow for
	* statically allocated event objects).
	*
	* If the AutoDestroy flag is set, the object is deleted once it
	* is processed.
	*/
	virtual void process() = 0;

	/// Determine if the current event is scheduled
	bool scheduled() const { return flags.isSet(Scheduled); }

	/// Squash the current event
	void squash() { flags.set(Squashed); }

	/// Check whether the event is squashed
	bool squashed() const { return flags.isSet(Squashed); }

	/// See if this is a SimExitEvent (without resorting to RTTI)
	bool isExitEvent() const { return flags.isSet(IsExitEvent); }

	/// Get the time that the event is scheduled
	Tick when() const { return _when; }

	/// Get the event priority
	Priority priority() const { return _priority; }

	#ifndef SWIG
	struct priority_compare
	: public std::binary_function<Event , Event , bool>
	{
	bool
	operator()(const Event l, const Event r) const
	{
	return l->when() >= r->when() \|\| l->priority() >= r->priority();
	}
	};

	virtual void serialize(std::ostream &os);
	virtual void unserialize(Checkpoint *cp, const std::string &section);
	#endif
	};

	#ifndef SWIG
	inline bool
	operator<(const Event &l, const Event &r)
	{
	return l.when() < r.when() \|\|
	(l.when() == r.when() && l.priority() < r.priority());
	}

	inline bool
	operator>(const Event &l, const Event &r)
	{
	return l.when() > r.when() \|\|
	(l.when() == r.when() && l.priority() > r.priority());
	}

	inline bool
	operator<=(const Event &l, const Event &r)
	{
	return l.when() < r.when() \|\|
	(l.when() == r.when() && l.priority() <= r.priority());
	}
	inline bool
	operator>=(const Event &l, const Event &r)
	{
	return l.when() > r.when() \|\|
	(l.when() == r.when() && l.priority() >= r.priority());
	}

	inline bool
	operator==(const Event &l, const Event &r)
	{
	return l.when() == r.when() && l.priority() == r.priority();
	}

	inline bool
	operator!=(const Event &l, const Event &r)
	{
	return l.when() != r.when() \|\| l.priority() != r.priority();
	}
	#endif

	/*
	* Queue of events sorted in time order
	*/
	class EventQueue : public Serializable
	{
	private:
	std::string objName;
	Event *head;

	void insert(Event *event);
	void remove(Event *event);

	EventQueue(const EventQueue &);
	const EventQueue &operator=(const EventQueue &);

	public:
	EventQueue(const std::string &n);

	virtual const std::string name() const { return objName; }

	// schedule the given event on this queue
	void schedule(Event *event, Tick when);
	void deschedule(Event *event);
	void reschedule(Event *event, Tick when, bool always = false);

	Tick nextTick() const { return head->when(); }
	Event *serviceOne();

	// process all events up to the given timestamp. we inline a
	// quick test to see if there are any events to process; if so,
	// call the internal out-of-line version to process them all.
	void
	serviceEvents(Tick when)
	{
	while (!empty()) {
	if (nextTick() > when)
	break;

	/**
	* @todo this assert is a good bug catcher. I need to
	* make it true again.
	*/
	//assert(head->when() >= when && "event scheduled in the past");
	serviceOne();
	}
	}

	// return true if no events are queued
	bool empty() const { return head == NULL; }

	void dump() const;

	bool debugVerify() const;

	/**
	* function for replacing the head of the event queue, so that a
	* different set of events can run without disturbing events that have
	* already been scheduled. Already scheduled events can be processed
	* by replacing the original head back.
	* USING THIS FUNCTION CAN BE DANGEROUS TO THE HEALTH OF THE SIMULATOR.
	* NOT RECOMMENDED FOR USE.
	*/
	Event* replaceHead(Event* s);

	#ifndef SWIG
	virtual void serialize(std::ostream &os);
	virtual void unserialize(Checkpoint *cp, const std::string &section);
	#endif
	};

	#ifndef SWIG
	class EventManager
	{
	protected:
	/** A pointer to this object's event queue */
	EventQueue *eventq;

	public:
	EventManager(EventManager &em) : eventq(em.queue()) {}
	EventManager(EventManager *em) : eventq(em ? em->queue() : NULL) {}
	EventManager(EventQueue *eq) : eventq(eq) {}

	EventQueue *
	queue() const
	{
	return eventq;
	}

	operator EventQueue *() const
	{
	return eventq;
	}

	void
	schedule(Event &event, Tick when)
	{
	eventq->schedule(&event, when);
	}

	void
	deschedule(Event &event)
	{
	eventq->deschedule(&event);
	}

	void
	reschedule(Event &event, Tick when, bool always = false)
	{
	eventq->reschedule(&event, when, always);
	}

	void
	schedule(Event *event, Tick when)
	{
	eventq->schedule(event, when);
	}

	void
	deschedule(Event *event)
	{
	eventq->deschedule(event);
	}

	void
	reschedule(Event *event, Tick when, bool always = false)
	{
	eventq->reschedule(event, when, always);
	}
	};

	inline void
	EventQueue::schedule(Event *event, Tick when)
	{
	// Typecasting Tick->Utick here since gcc
	// complains about signed overflow
	assert((UTick)when >= (UTick)curTick());
	assert(!event->scheduled());
	assert(event->initialized());

	event->setWhen(when, this);
	insert(event);
	event->flags.set(Event::Scheduled);
	if (this == &mainEventQueue)
	event->flags.set(Event::IsMainQueue);
	else
	event->flags.clear(Event::IsMainQueue);

	if (DTRACE(Event))
	event->trace("scheduled");
	}

	inline void
	EventQueue::deschedule(Event *event)
	{
	assert(event->scheduled());
	assert(event->initialized());

	remove(event);

	event->flags.clear(Event::Squashed);
	event->flags.clear(Event::Scheduled);

	if (DTRACE(Event))
	event->trace("descheduled");

	if (event->flags.isSet(Event::AutoDelete))
	delete event;
	}

	inline void
	EventQueue::reschedule(Event *event, Tick when, bool always)
	{
	// Typecasting Tick->Utick here since gcc
	// complains about signed overflow
	assert((UTick)when >= (UTick)curTick());
	assert(always \|\| event->scheduled());
	assert(event->initialized());

	if (event->scheduled())
	remove(event);

	event->setWhen(when, this);
	insert(event);
	event->flags.clear(Event::Squashed);
	event->flags.set(Event::Scheduled);
	if (this == &mainEventQueue)
	event->flags.set(Event::IsMainQueue);
	else
	event->flags.clear(Event::IsMainQueue);

	if (DTRACE(Event))
	event->trace("rescheduled");
	}

	template <class T, void (T::* F)()>
	void
	DelayFunction(EventQueue eventq, Tick when, T object)
	{
	class DelayEvent : public Event
	{
	private:
	T *object;

	public:
	DelayEvent(T *o)
	: Event(Default_Pri, AutoDelete), object(o)
	{ }
	void process() { (object->*F)(); }
	const char *description() const { return "delay"; }
	};

	eventq->schedule(new DelayEvent(object), when);
	}

	template <class T, void (T::* F)()>
	class EventWrapper : public Event
	{
	private:
	T *object;

	public:
	EventWrapper(T *obj, bool del = false, Priority p = Default_Pri)
	: Event(p), object(obj)
	{
	if (del)
	setFlags(AutoDelete);
	}

	EventWrapper(T &obj, bool del = false, Priority p = Default_Pri)
	: Event(p), object(&obj)
	{
	if (del)
	setFlags(AutoDelete);
	}

	void process() { (object->*F)(); }

	const std::string
	name() const
	{
	return object->name() + ".wrapped_event";
	}

	const char *description() const { return "EventWrapped"; }
	};
	#endif

	#endif // __SIM_EVENTQ_HH__