clocked_object.hh revision 10000:99bd071911cf
14683Sgblack@eecs.umich.edu/* 24683Sgblack@eecs.umich.edu * Copyright (c) 2012-2013 ARM Limited 34683Sgblack@eecs.umich.edu * Copyright (c) 2013 Cornell University 44683Sgblack@eecs.umich.edu * All rights reserved 54683Sgblack@eecs.umich.edu * 64683Sgblack@eecs.umich.edu * The license below extends only to copyright in the software and shall 74683Sgblack@eecs.umich.edu * not be construed as granting a license to any other intellectual 84683Sgblack@eecs.umich.edu * property including but not limited to intellectual property relating 94683Sgblack@eecs.umich.edu * to a hardware implementation of the functionality of the software 104683Sgblack@eecs.umich.edu * licensed hereunder. You may use the software subject to the license 114683Sgblack@eecs.umich.edu * terms below provided that you ensure that this notice is replicated 124683Sgblack@eecs.umich.edu * unmodified and in its entirety in all distributions of the software, 134683Sgblack@eecs.umich.edu * modified or unmodified, in source code or in binary form. 144683Sgblack@eecs.umich.edu * 154683Sgblack@eecs.umich.edu * Redistribution and use in source and binary forms, with or without 164683Sgblack@eecs.umich.edu * modification, are permitted provided that the following conditions are 174683Sgblack@eecs.umich.edu * met: redistributions of source code must retain the above copyright 184683Sgblack@eecs.umich.edu * notice, this list of conditions and the following disclaimer; 194683Sgblack@eecs.umich.edu * redistributions in binary form must reproduce the above copyright 204683Sgblack@eecs.umich.edu * notice, this list of conditions and the following disclaimer in the 214683Sgblack@eecs.umich.edu * documentation and/or other materials provided with the distribution; 224683Sgblack@eecs.umich.edu * neither the name of the copyright holders nor the names of its 234683Sgblack@eecs.umich.edu * contributors may be used to endorse or promote products derived from 244683Sgblack@eecs.umich.edu * this software without specific prior written permission. 254683Sgblack@eecs.umich.edu * 264683Sgblack@eecs.umich.edu * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 274683Sgblack@eecs.umich.edu * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 284683Sgblack@eecs.umich.edu * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 294683Sgblack@eecs.umich.edu * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 304683Sgblack@eecs.umich.edu * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 314683Sgblack@eecs.umich.edu * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 324683Sgblack@eecs.umich.edu * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 334683Sgblack@eecs.umich.edu * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 344683Sgblack@eecs.umich.edu * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 354683Sgblack@eecs.umich.edu * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 364683Sgblack@eecs.umich.edu * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 374683Sgblack@eecs.umich.edu * 384683Sgblack@eecs.umich.edu * Authors: Andreas Hansson 394683Sgblack@eecs.umich.edu * Christopher Torng 404683Sgblack@eecs.umich.edu */ 414683Sgblack@eecs.umich.edu 424683Sgblack@eecs.umich.edu/** 434683Sgblack@eecs.umich.edu * @file 444683Sgblack@eecs.umich.edu * ClockedObject declaration and implementation. 454683Sgblack@eecs.umich.edu */ 464683Sgblack@eecs.umich.edu 474683Sgblack@eecs.umich.edu#ifndef __SIM_CLOCKED_OBJECT_HH__ 484683Sgblack@eecs.umich.edu#define __SIM_CLOCKED_OBJECT_HH__ 494683Sgblack@eecs.umich.edu 504683Sgblack@eecs.umich.edu#include "base/intmath.hh" 514683Sgblack@eecs.umich.edu#include "base/misc.hh" 524683Sgblack@eecs.umich.edu#include "params/ClockedObject.hh" 534683Sgblack@eecs.umich.edu#include "sim/core.hh" 544683Sgblack@eecs.umich.edu#include "sim/clock_domain.hh" 554683Sgblack@eecs.umich.edu#include "sim/sim_object.hh" 564683Sgblack@eecs.umich.edu 574683Sgblack@eecs.umich.edu/** 584683Sgblack@eecs.umich.edu * The ClockedObject class extends the SimObject with a clock and 594683Sgblack@eecs.umich.edu * accessor functions to relate ticks to the cycles of the object. 604683Sgblack@eecs.umich.edu */ 614683Sgblack@eecs.umich.educlass ClockedObject : public SimObject 624683Sgblack@eecs.umich.edu{ 634683Sgblack@eecs.umich.edu 644683Sgblack@eecs.umich.edu private: 654683Sgblack@eecs.umich.edu 664683Sgblack@eecs.umich.edu // the tick value of the next clock edge (>= curTick()) at the 674683Sgblack@eecs.umich.edu // time of the last call to update() 684683Sgblack@eecs.umich.edu mutable Tick tick; 694683Sgblack@eecs.umich.edu 704683Sgblack@eecs.umich.edu // The cycle counter value corresponding to the current value of 714683Sgblack@eecs.umich.edu // 'tick' 724683Sgblack@eecs.umich.edu mutable Cycles cycle; 734683Sgblack@eecs.umich.edu 744683Sgblack@eecs.umich.edu /** 754683Sgblack@eecs.umich.edu * Prevent inadvertent use of the copy constructor and assignment 764683Sgblack@eecs.umich.edu * operator by making them private. 774683Sgblack@eecs.umich.edu */ 784683Sgblack@eecs.umich.edu ClockedObject(ClockedObject&); 794683Sgblack@eecs.umich.edu ClockedObject& operator=(ClockedObject&); 804683Sgblack@eecs.umich.edu 814683Sgblack@eecs.umich.edu /** 824683Sgblack@eecs.umich.edu * Align cycle and tick to the next clock edge if not already done. 834683Sgblack@eecs.umich.edu */ 844683Sgblack@eecs.umich.edu void update() const 854683Sgblack@eecs.umich.edu { 864683Sgblack@eecs.umich.edu // both tick and cycle are up-to-date and we are done, note 874683Sgblack@eecs.umich.edu // that the >= is important as it captures cases where tick 884683Sgblack@eecs.umich.edu // has already passed curTick() 894683Sgblack@eecs.umich.edu if (tick >= curTick()) 904683Sgblack@eecs.umich.edu return; 914683Sgblack@eecs.umich.edu 92 // optimise for the common case and see if the tick should be 93 // advanced by a single clock period 94 tick += clockPeriod(); 95 ++cycle; 96 97 // see if we are done at this point 98 if (tick >= curTick()) 99 return; 100 101 // if not, we have to recalculate the cycle and tick, we 102 // perform the calculations in terms of relative cycles to 103 // allow changes to the clock period in the future 104 Cycles elapsedCycles(divCeil(curTick() - tick, clockPeriod())); 105 cycle += elapsedCycles; 106 tick += elapsedCycles * clockPeriod(); 107 } 108 109 /** 110 * The clock domain this clocked object belongs to 111 */ 112 ClockDomain &clockDomain; 113 114 protected: 115 116 /** 117 * Create a clocked object and set the clock domain based on the 118 * parameters. 119 */ 120 ClockedObject(const ClockedObjectParams* p) : 121 SimObject(p), tick(0), cycle(0), clockDomain(*p->clk_domain) 122 { 123 // Register with the clock domain, so that if the clock domain 124 // frequency changes, we can update this object's tick. 125 clockDomain.registerWithClockDomain(this); 126 } 127 128 /** 129 * Virtual destructor due to inheritance. 130 */ 131 virtual ~ClockedObject() { } 132 133 /** 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. 137 */ 138 void resetClock() const 139 { 140 Cycles elapsedCycles(divCeil(curTick(), clockPeriod())); 141 cycle = elapsedCycles; 142 tick = elapsedCycles * clockPeriod(); 143 } 144 145 public: 146 147 /** 148 * Update the tick to the current tick. 149 * 150 */ 151 inline void updateClockPeriod() const 152 { 153 update(); 154 } 155 156 /** 157 * Determine the tick when a cycle begins, by default the current 158 * one, but the argument also enables the caller to determine a 159 * future cycle. 160 * 161 * @param cycles The number of cycles into the future 162 * 163 * @return The tick when the clock edge occurs 164 */ 165 inline Tick clockEdge(Cycles cycles = Cycles(0)) const 166 { 167 // align tick to the next clock edge 168 update(); 169 170 // figure out when this future cycle is 171 return tick + clockPeriod() * cycles; 172 } 173 174 /** 175 * Determine the current cycle, corresponding to a tick aligned to 176 * a clock edge. 177 * 178 * @return The current cycle count 179 */ 180 inline Cycles curCycle() const 181 { 182 // align cycle to the next clock edge. 183 update(); 184 185 return cycle; 186 } 187 188 /** 189 * Based on the clock of the object, determine the tick when the next 190 * cycle begins, in other words, return the next clock edge. 191 * (This can never be the current tick.) 192 * 193 * @return The tick when the next cycle starts 194 */ 195 Tick nextCycle() const 196 { return clockEdge(Cycles(1)); } 197 198 inline uint64_t frequency() const 199 { 200 return SimClock::Frequency / clockPeriod(); 201 } 202 203 inline Tick clockPeriod() const 204 { 205 return clockDomain.clockPeriod(); 206 } 207 208 inline Cycles ticksToCycles(Tick t) const 209 { return Cycles(divCeil(t, clockPeriod())); } 210 211}; 212 213#endif //__SIM_CLOCKED_OBJECT_HH__ 214