1/*
2 * Copyright (c) 2000-2005 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;

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31
32/* @file
33 * EventQueue interfaces
34 */
35
36#ifndef __SIM_EVENTQ_HH__
37#define __SIM_EVENTQ_HH__
38
39#include <algorithm>
40#include <cassert>
41#include <map>
42#include <string>
43#include <vector>
44
45#include "base/fast_alloc.hh"
46#include "base/misc.hh"
47#include "base/trace.hh"
48#include "sim/serialize.hh"
49#include "sim/host.hh"
50
51class EventQueue; // forward declaration
52
53//////////////////////
54//
55// Main Event Queue
56//
57// Events on this queue are processed at the *beginning* of each
58// cycle, before the pipeline simulation is performed.
59//
60// defined in eventq.cc
61//
62//////////////////////
63extern EventQueue mainEventQueue;
64
65/*
66 * An item on an event queue. The action caused by a given
67 * event is specified by deriving a subclass and overriding the
68 * process() member function.
69 *
70 * Caution, the order of members is chosen to maximize data packing.
71 */
72class Event : public Serializable, public FastAlloc
73{
74 friend class EventQueue;
75
76 private:
77 Event *next;
78
79 /// queue to which this event belongs (though it may or may not be
80 /// scheduled on this queue yet)
81 EventQueue *_queue;
82
83 Tick _when; //!< timestamp when event should be processed
84 short _priority; //!< event priority
85 short _flags;
86
87#ifndef NDEBUG
88 /// Global counter to generate unique IDs for Event instances
89 static Counter instanceCounter;
90
91 /// This event's unique ID. We can also use pointer values for
92 /// this but they're not consistent across runs making debugging
93 /// more difficult. Thus we use a global counter value when
94 /// debugging.
95 Counter instance;
96#endif
97
98#ifdef DEBUG_EVENTQ
99 Tick whenCreated; //!< time created
100 Tick whenScheduled; //!< time scheduled
101#endif
102 protected:
103 enum Flags {
104 None = 0x0,
105 Squashed = 0x1,
106 Scheduled = 0x2,
107 AutoDelete = 0x4,
108 AutoSerialize = 0x8,
109 IsExitEvent = 0x10
110 };
111
112 bool getFlags(Flags f) const { return (_flags & f) == f; }
113 void setFlags(Flags f) { _flags |= f; }
114 void clearFlags(Flags f) { _flags &= ~f; }
115
116 protected:
117 EventQueue *queue() const { return _queue; }
118
119 // This function isn't really useful if TRACING_ON is not defined
120 virtual void trace(const char *action); //!< trace event activity
121
122 public:
123 /// Event priorities, to provide tie-breakers for events scheduled
124 /// at the same cycle. Most events are scheduled at the default
125 /// priority; these values are used to control events that need to
126 /// be ordered within a cycle.
127 enum Priority {
128 /// Minimum priority
129 Minimum_Pri = SHRT_MIN,
130
131 /// If we enable tracing on a particular cycle, do that as the
132 /// very first thing so we don't miss any of the events on
133 /// that cycle (even if we enter the debugger).
134 Trace_Enable_Pri = -101,
135
136 /// Breakpoints should happen before anything else (except
137 /// enabling trace output), so we don't miss any action when
138 /// debugging.

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165 /// everything else, but before exit.
166 Stat_Event_Pri = 90,
167
168 /// Progress events come at the end.
169 Progress_Event_Pri = 95,
170
171 /// If we want to exit on this cycle, it's the very last thing
172 /// we do.
173 Sim_Exit_Pri = 100,
174
175 /// Maximum priority
176 Maximum_Pri = SHRT_MAX
177 };
178
179 /*
180 * Event constructor
181 * @param queue that the event gets scheduled on
182 */
183 Event(EventQueue *q, Priority p = Default_Pri)
184 : next(NULL), _queue(q), _priority(p), _flags(None)
185 {
186#ifndef NDEBUG
187 instance = ++instanceCounter;
188#endif
189#ifdef EVENTQ_DEBUG
190 whenCreated = curTick;
191 whenScheduled = 0;
192#endif
193 }
194
195 virtual
196 ~Event()
197 {
198 }
199
200 virtual const std::string
201 name() const
202 {
203#ifndef NDEBUG
204 return csprintf("Event_%d", instance);
205#else
206 return csprintf("Event_%x", (uintptr_t)this);
207#endif
208 }
209
210 /// Return a C string describing the event. This string should
211 /// *not* be dynamically allocated; just a const char array
212 /// describing the event class.
213 virtual const char *description() const;
214
215 /// Dump the current event data
216 void dump() const;
217
218 public:
219 /*
220 * This member function is invoked when the event is processed
221 * (occurs). There is no default implementation; each subclass
222 * must provide its own implementation. The event is not
223 * automatically deleted after it is processed (to allow for
224 * statically allocated event objects).
225 *
226 * If the AutoDestroy flag is set, the object is deleted once it
227 * is processed.
228 */
229 virtual void process() = 0;
230
231 /// Determine if the current event is scheduled
232 bool scheduled() const { return getFlags(Scheduled); }
233
234 /// Schedule the event with the current priority or default priority
235 void schedule(Tick t);
236
237 /// Reschedule the event with the current priority
238 // always parameter means to schedule if not already scheduled
239 void reschedule(Tick t, bool always = false);
240
241 /// Remove the event from the current schedule
242 void deschedule();
243
244 /// Squash the current event
245 void squash() { setFlags(Squashed); }
246
247 /// Check whether the event is squashed
248 bool squashed() const { return getFlags(Squashed); }
249
250 /// See if this is a SimExitEvent (without resorting to RTTI)
251 bool isExitEvent() const { return getFlags(IsExitEvent); }
252
253 /// Get the time that the event is scheduled
254 Tick when() const { return _when; }
255
256 /// Get the event priority
257 int priority() const { return _priority; }
258
259 struct priority_compare
260 : public std::binary_function<Event *, Event *, bool>
261 {
262 bool
263 operator()(const Event *l, const Event *r) const
264 {
265 return l->when() >= r->when() || l->priority() >= r->priority();
266 }
267 };
268
269 virtual void serialize(std::ostream &os);
270 virtual void unserialize(Checkpoint *cp, const std::string &section);
271};
272

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342
343 virtual const std::string name() const { return objName; }
344
345 // schedule the given event on this queue
346 void schedule(Event *ev);
347 void deschedule(Event *ev);
348 void reschedule(Event *ev);
349
350 Tick nextTick() const { return head->when(); }
351 Event *serviceOne();
352
353 // process all events up to the given timestamp. we inline a
354 // quick test to see if there are any events to process; if so,
355 // call the internal out-of-line version to process them all.
356 void
357 serviceEvents(Tick when)
358 {
359 while (!empty()) {
360 if (nextTick() > when)
361 break;
362
363 /**
364 * @todo this assert is a good bug catcher. I need to
365 * make it true again.
366 */
367 //assert(head->when() >= when && "event scheduled in the past");
368 serviceOne();
369 }
370 }
371
372 // default: process all events up to 'now' (curTick)
373 void serviceEvents() { serviceEvents(curTick); }
374
375 // return true if no events are queued
376 bool empty() const { return head == NULL; }
377
378 void dump() const;
379
380 Tick nextEventTime() { return empty() ? curTick : head->when(); }
381
382 virtual void serialize(std::ostream &os);
383 virtual void unserialize(Checkpoint *cp, const std::string &section);
384};
385
386

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394//////////////////////
395
396// schedule at specified time (place on event queue specified via
397// constructor)
398inline void
399Event::schedule(Tick t)
400{
401 assert(!scheduled());
402 assert(t >= curTick);
403
404 setFlags(Scheduled);
405#ifdef DEBUG_EVENTQ
406 whenScheduled = curTick;
407#endif
408 _when = t;
409 _queue->schedule(this);
410}
411
412inline void
413Event::deschedule()
414{
415 assert(scheduled());
416
417 clearFlags(Squashed);
418 clearFlags(Scheduled);
419 _queue->deschedule(this);
420}
421
422inline void
423Event::reschedule(Tick t, bool always)
424{
425 assert(scheduled() || always);
426 assert(t >= curTick);
427
428#ifdef DEBUG_EVENTQ
429 whenScheduled = curTick;
430#endif
431 _when = t;
432
433 if (scheduled()) {
434 clearFlags(Squashed);
435 _queue->reschedule(this);
436 } else {
437 setFlags(Scheduled);
438 _queue->schedule(this);
439 }
440}
441
442inline void
443EventQueue::schedule(Event *event)
444{
445 insert(event);
446 if (DTRACE(Event))
447 event->trace("scheduled");
448}
449
450inline void
451EventQueue::deschedule(Event *event)
452{
453 remove(event);
454 if (DTRACE(Event))
455 event->trace("descheduled");
456
457 if (event->getFlags(Event::AutoDelete))
458 delete event;
459}
460
461inline void
462EventQueue::reschedule(Event *event)
463{
464 remove(event);
465 insert(event);
466 if (DTRACE(Event))
467 event->trace("rescheduled");
468}
469
470#endif // __SIM_EVENTQ_HH__