sim/eventq.hh

   1 /*
   2  * Copyright (c) 2003 The Regents of The University of Michigan
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions are
   7  * met: redistributions of source code must retain the above copyright
   8  * notice, this list of conditions and the following disclaimer;
   9  * redistributions in binary form must reproduce the above copyright
  10  * notice, this list of conditions and the following disclaimer in the
  11  * documentation and/or other materials provided with the distribution;
  12  * neither the name of the copyright holders nor the names of its
  13  * contributors may be used to endorse or promote products derived from
  14  * this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  17  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  18  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  19  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  20  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  21  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  22  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  26  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 /* @file
  30  * EventQueue interfaces
  31  */
  32
  33 #ifndef __EVENTQ_HH__
  34 #define __EVENTQ_HH__
  35
  36 #include <assert.h>
  37
  38 #include <algorithm>
  39 #include <map>
  40 #include <string>
  41 #include <vector>
  42
  43 #include "sim/host.hh"  // for Tick
  44
  45 #include "base/fast_alloc.hh"
  46 #include "sim/serialize.hh"
  47 #include "base/trace.hh"
  48
  49 class EventQueue;       // forward declaration
  50
  51 /*
  52  * An item on an event queue.  The action caused by a given
  53  * event is specified by deriving a subclass and overriding the
  54  * process() member function.
  55  */
  56 class Event : public Serializeable, public FastAlloc
  57 {
  58     friend class EventQueue;
  59
  60   private:
  61     /// queue to which this event belongs (though it may or may not be
  62     /// scheduled on this queue yet)
  63     EventQueue *queue;
  64
  65     Event *next;
  66
  67     Tick _when; //!< timestamp when event should be processed
  68     int _priority;      //!< event priority
  69     char _flags;
  70
  71   protected:
  72     enum Flags {
  73         None = 0x0,
  74         Squashed = 0x1,
  75         Scheduled = 0x2,
  76         AutoDelete = 0x4
  77     };
  78
  79     bool getFlags(Flags f) const { return (_flags & f) == f; }
  80     void setFlags(Flags f) { _flags |= f; }
  81     void clearFlags(Flags f) { _flags &= ~f; }
  82
  83   protected:
  84     EventQueue *theQueue() const { return queue; }
  85
  86 #if TRACING_ON
  87     Tick when_created;  //!< Keep track of creation time For debugging
  88     Tick when_scheduled;        //!< Keep track of creation time For debugging
  89
  90     virtual void trace(const char *action);     //!< trace event activity
  91 #else
  92     void trace(const char *) {}
  93 #endif
  94
  95     unsigned annotated_value;
  96
  97   public:
  98
  99     static const std::string defaultName;
 100
 101     /*
 102      * Event constructor
 103      * @param queue that the event gets scheduled on
 104      */
 105     Event(EventQueue *q, int p = 0)
 106         : Serializeable(defaultName), queue(q), next(NULL),
 107           _priority(p), _flags(None),
 108 #if TRACING_ON
 109           when_created(curTick), when_scheduled(0),
 110 #endif
 111           annotated_value(0)
 112     {
 113     }
 114
 115     ~Event() {}
 116
 117     /// Determine if the current event is scheduled
 118     bool scheduled() const { return getFlags(Scheduled); }
 119
 120     /// Schedule the event with the current priority or default priority
 121     void schedule(Tick t);
 122
 123     /// Schedule the event with a specific priority
 124     void schedule(Tick t, int priority);
 125
 126     /// Reschedule the event with the current priority
 127     void reschedule(Tick t);
 128
 129     /// Reschedule the event with a specific priority
 130     void reschedule(Tick t, int priority);
 131
 132     /// Remove the event from the current schedule
 133     void deschedule();
 134
 135     /// Return a C string describing the event.  This string should
 136     /// *not* be dynamically allocated; just a const char array
 137     /// describing the event class.
 138     virtual const char *description();
 139
 140     /// Dump the current event data
 141     void dump();
 142
 143     /*
 144      * This member function is invoked when the event is processed
 145      * (occurs).  There is no default implementation; each subclass
 146      * must provide its own implementation.  The event is not
 147      * automatically deleted after it is processed (to allow for
 148      * statically allocated event objects).
 149      *
 150      * If the AutoDestroy flag is set, the object is deleted once it
 151      * is processed.
 152      */
 153     virtual void process() = 0;
 154
 155     void annotate(unsigned value) { annotated_value = value; };
 156     unsigned annotation() { return annotated_value; }
 157
 158     /// Squash the current event
 159     void squash() { setFlags(Squashed); }
 160
 161     /// Check whether the event is squashed
 162     bool squashed() { return getFlags(Squashed); }
 163
 164     /// Get the time that the event is scheduled
 165     Tick when() const { return _when; }
 166
 167     /// Get the event priority
 168     int priority() const { return _priority; }
 169
 170     struct priority_compare :
 171     public std::binary_function<Event *, Event *, bool>
 172     {
 173         bool operator()(const Event *l, const Event *r) const {
 174             return l->when() >= r->when() || l->priority() >= r->priority();
 175         }
 176     };
 177 };
 178
 179 template <class T, void (T::* F)()>
 180 void
 181 DelayFunction(Tick when, T *object)
 182 {
 183     class DelayEvent : public Event
 184     {
 185       private:
 186         T *object;
 187
 188       public:
 189         DelayEvent(Tick when, T *o)
 190             : Event(&mainEventQueue), object(o)
 191             { setFlags(AutoDestroy); schedule(when); }
 192         void process() { (object->*F)(); }
 193         const char *description() { return "delay"; }
 194     };
 195
 196     new DelayEvent(when, object);
 197 }
 198
 199 /*
 200  * Queue of events sorted in time order
 201  */
 202 class EventQueue : public Serializeable
 203 {
 204   private:
 205     Event *head;
 206
 207     void insert(Event *event);
 208     void remove(Event *event);
 209
 210   public:
 211
 212     // constructor
 213     EventQueue(const std::string &n)
 214         : Serializeable(n), head(NULL)
 215     {}
 216
 217     // schedule the given event on this queue
 218     void schedule(Event *ev);
 219     void deschedule(Event *ev);
 220     void reschedule(Event *ev);
 221
 222     Tick nextTick() { return head->when(); }
 223     void serviceOne();
 224
 225     // process all events up to the given timestamp.  we inline a
 226     // quick test to see if there are any events to process; if so,
 227     // call the internal out-of-line version to process them all.
 228     void serviceEvents(Tick when) {
 229         while (!empty()) {
 230             if (nextTick() > when)
 231                 break;
 232
 233             assert(head->when() >= when && "event scheduled in the past");
 234             serviceOne();
 235         }
 236     }
 237
 238     // default: process all events up to 'now' (curTick)
 239     void serviceEvents() { serviceEvents(curTick); }
 240
 241     // return true if no events are queued
 242     bool empty() { return head == NULL; }
 243
 244     void dump();
 245
 246     Tick nextEventTime() { return empty() ? curTick : head->when(); }
 247
 248     virtual void nameChildren();
 249     virtual void serialize();
 250 };
 251
 252
 253 //////////////////////
 254 //
 255 // inline functions
 256 //
 257 // can't put these inside declaration due to circular dependence
 258 // between Event and EventQueue classes.
 259 //
 260 //////////////////////
 261
 262 // schedule at specified time (place on event queue specified via
 263 // constructor)
 264 inline void
 265 Event::schedule(Tick t)
 266 {
 267     assert(!scheduled());
 268     setFlags(Scheduled);
 269 #if TRACING_ON
 270     when_scheduled = curTick;
 271 #endif
 272     _when = t;
 273     queue->schedule(this);
 274 }
 275
 276 inline void
 277 Event::schedule(Tick t, int p)
 278 {
 279     _priority = p;
 280     schedule(t);
 281 }
 282
 283 inline void
 284 Event::deschedule()
 285 {
 286     assert(scheduled());
 287
 288     clearFlags(Squashed);
 289     clearFlags(Scheduled);
 290     queue->deschedule(this);
 291 }
 292
 293 inline void
 294 Event::reschedule(Tick t)
 295 {
 296     assert(scheduled());
 297     clearFlags(Squashed);
 298
 299 #if TRACING_ON
 300     when_scheduled = curTick;
 301 #endif
 302     _when = t;
 303     queue->reschedule(this);
 304 }
 305
 306 inline void
 307 Event::reschedule(Tick t, int p)
 308 {
 309     _priority = p;
 310     reschedule(t);
 311 }
 312
 313 inline void
 314 EventQueue::schedule(Event *event)
 315 {
 316     insert(event);
 317     if (DTRACE(Event))
 318         event->trace("scheduled");
 319 }
 320
 321 inline void
 322 EventQueue::deschedule(Event *event)
 323 {
 324     remove(event);
 325     if (DTRACE(Event))
 326         event->trace("descheduled");
 327 }
 328
 329 inline void
 330 EventQueue::reschedule(Event *event)
 331 {
 332     remove(event);
 333     insert(event);
 334     if (DTRACE(Event))
 335         event->trace("rescheduled");
 336 }
 337
 338
 339 //////////////////////
 340 //
 341 // Main Event Queue
 342 //
 343 // Events on this queue are processed at the *beginning* of each
 344 // cycle, before the pipeline simulation is performed.
 345 //
 346 // defined in eventq.cc
 347 //
 348 //////////////////////
 349 extern EventQueue mainEventQueue;
 350
 351 #endif // __EVENTQ_HH__