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3 * Copyright (c) 2013 Cornell University
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38 * Authors: Andreas Hansson
41 * David Guillen Fandos
46 * ClockedObject declaration and implementation.
49 #ifndef __SIM_CLOCKED_OBJECT_HH__
50 #define __SIM_CLOCKED_OBJECT_HH__
52 #include "base/callback.hh"
53 #include "base/intmath.hh"
54 #include "enums/PwrState.hh"
55 #include "params/ClockedObject.hh"
56 #include "sim/core.hh"
57 #include "sim/clock_domain.hh"
58 #include "sim/sim_object.hh"
61 * Helper class for objects that need to be clocked. Clocked objects
62 * typically inherit from this class. Objects that need SimObject
63 * functionality as well should inherit from ClockedObject.
69 // the tick value of the next clock edge (>= curTick()) at the
70 // time of the last call to update()
73 // The cycle counter value corresponding to the current value of
78 * Align cycle and tick to the next clock edge if not already done. When
79 * complete, tick must be at least curTick().
83 // both tick and cycle are up-to-date and we are done, note
84 // that the >= is important as it captures cases where tick
85 // has already passed curTick()
86 if (tick >= curTick())
89 // optimise for the common case and see if the tick should be
90 // advanced by a single clock period
91 tick += clockPeriod();
94 // see if we are done at this point
95 if (tick >= curTick())
98 // if not, we have to recalculate the cycle and tick, we
99 // perform the calculations in terms of relative cycles to
100 // allow changes to the clock period in the future
101 Cycles elapsedCycles(divCeil(curTick() - tick, clockPeriod()));
102 cycle += elapsedCycles;
103 tick += elapsedCycles * clockPeriod();
107 * The clock domain this clocked object belongs to
109 ClockDomain &clockDomain;
114 * Create a clocked object and set the clock domain based on the
117 Clocked(ClockDomain &clk_domain)
118 : tick(0), cycle(0), clockDomain(clk_domain)
120 // Register with the clock domain, so that if the clock domain
121 // frequency changes, we can update this object's tick.
122 clockDomain.registerWithClockDomain(this);
125 Clocked(Clocked &) = delete;
126 Clocked &operator=(Clocked &) = delete;
129 * Virtual destructor due to inheritance.
131 virtual ~Clocked() { }
134 * Reset the object's clock using the current global tick value. Likely
135 * to be used only when the global clock is reset. Currently, this done
136 * only when Ruby is done warming up the memory system.
138 void resetClock() const
140 Cycles elapsedCycles(divCeil(curTick(), clockPeriod()));
141 cycle = elapsedCycles;
142 tick = elapsedCycles * clockPeriod();
148 * Update the tick to the current tick.
151 inline void updateClockPeriod() const
157 * Determine the tick when a cycle begins, by default the current one, but
158 * the argument also enables the caller to determine a future cycle. When
159 * curTick() is on a clock edge, the number of cycles in the parameter is
160 * added to curTick() to be returned. When curTick() is not aligned to a
161 * clock edge, the number of cycles in the parameter is added to the next
164 * @param cycles The number of cycles into the future
166 * @return The start tick when the requested clock edge occurs. Precisely,
168 * curTick() + [0, clockPeriod()) + clockPeriod() * cycles
170 inline Tick clockEdge(Cycles cycles = Cycles(0)) const
172 // align tick to the next clock edge
175 // figure out when this future cycle is
176 return tick + clockPeriod() * cycles;
180 * Determine the current cycle, corresponding to a tick aligned to
183 * @return When curTick() is on a clock edge, return the Cycle corresponding
184 * to that clock edge. When curTick() is not on a clock edge, return the
185 * Cycle corresponding to the next clock edge.
187 inline Cycles curCycle() const
189 // align cycle to the next clock edge.
196 * Based on the clock of the object, determine the start tick of the first
197 * cycle that is at least one cycle in the future. When curTick() is at the
198 * current cycle edge, this returns the next clock edge. When calling this
199 * during the middle of a cycle, this returns 2 clock edges in the future.
201 * @return The start tick of the first cycle that is at least one cycle in
202 * the future. Precisely, the returned tick can be in the range
203 * curTick() + [clockPeriod(), 2 * clockPeriod())
205 Tick nextCycle() const
206 { return clockEdge(Cycles(1)); }
208 inline uint64_t frequency() const
210 return SimClock::Frequency / clockPeriod();
213 inline Tick clockPeriod() const
215 return clockDomain.clockPeriod();
218 inline double voltage() const
220 return clockDomain.voltage();
223 inline Cycles ticksToCycles(Tick t) const
224 { return Cycles(divCeil(t, clockPeriod())); }
226 inline Tick cyclesToTicks(Cycles c) const
227 { return clockPeriod() * c; }
231 * The ClockedObject class extends the SimObject with a clock and
232 * accessor functions to relate ticks to the cycles of the object.
235 : public SimObject, public Clocked
238 ClockedObject(const ClockedObjectParams *p);
240 /** Parameters of ClockedObject */
241 typedef ClockedObjectParams Params;
242 const Params* params() const
243 { return reinterpret_cast<const Params*>(_params); }
245 void serialize(CheckpointOut &cp) const override;
246 void unserialize(CheckpointIn &cp) override;
248 inline Enums::PwrState pwrState() const
249 { return _currPwrState; }
251 inline std::string pwrStateName() const
252 { return Enums::PwrStateStrings[_currPwrState]; }
254 /** Returns the percentage residency for each power state */
255 std::vector<double> pwrStateWeights() const;
258 * Record stats values like state residency by computing the time
259 * difference from previous update. Also, updates the previous evaluation
260 * tick once all stats are recorded.
261 * Usually called on power state change and stats dump callback.
265 void pwrState(Enums::PwrState);
266 void regStats() override;
270 /** To keep track of the current power state */
271 Enums::PwrState _currPwrState;
275 Stats::Scalar numPwrStateTransitions;
276 Stats::Distribution pwrStateClkGateDist;
277 Stats::Vector pwrStateResidencyTicks;
281 class ClockedObjectDumpCallback : public Callback
285 ClockedObjectDumpCallback(ClockedObject *co_t) : co(co_t) {}
286 virtual void process() { co->computeStats(); };
289 #endif //__SIM_CLOCKED_OBJECT_HH__