packet_queue.hh revision 7823
14486Sbinkertn@umich.edu/* 24486Sbinkertn@umich.edu * Copyright (c) 2006 The Regents of The University of Michigan 34486Sbinkertn@umich.edu * All rights reserved. 44486Sbinkertn@umich.edu * 54486Sbinkertn@umich.edu * Redistribution and use in source and binary forms, with or without 64486Sbinkertn@umich.edu * modification, are permitted provided that the following conditions are 74486Sbinkertn@umich.edu * met: redistributions of source code must retain the above copyright 84486Sbinkertn@umich.edu * notice, this list of conditions and the following disclaimer; 94486Sbinkertn@umich.edu * redistributions in binary form must reproduce the above copyright 104486Sbinkertn@umich.edu * notice, this list of conditions and the following disclaimer in the 114486Sbinkertn@umich.edu * documentation and/or other materials provided with the distribution; 124486Sbinkertn@umich.edu * neither the name of the copyright holders nor the names of its 134486Sbinkertn@umich.edu * contributors may be used to endorse or promote products derived from 144486Sbinkertn@umich.edu * this software without specific prior written permission. 154486Sbinkertn@umich.edu * 164486Sbinkertn@umich.edu * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 174486Sbinkertn@umich.edu * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 184486Sbinkertn@umich.edu * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 194486Sbinkertn@umich.edu * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 204486Sbinkertn@umich.edu * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 214486Sbinkertn@umich.edu * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 224486Sbinkertn@umich.edu * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 234486Sbinkertn@umich.edu * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 244486Sbinkertn@umich.edu * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 254486Sbinkertn@umich.edu * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 264486Sbinkertn@umich.edu * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 274486Sbinkertn@umich.edu * 284486Sbinkertn@umich.edu * Authors: Ali Saidi 293102SN/A */ 303102SN/A 313102SN/A#ifndef __MEM_TPORT_HH__ 322667SN/A#define __MEM_TPORT_HH__ 332998SN/A 343584SN/A/** 352667SN/A * @file 364486Sbinkertn@umich.edu * 374486Sbinkertn@umich.edu * Declaration of SimpleTimingPort. 384486Sbinkertn@umich.edu */ 394486Sbinkertn@umich.edu 404486Sbinkertn@umich.edu#include "mem/port.hh" 414486Sbinkertn@umich.edu#include "sim/eventq.hh" 424486Sbinkertn@umich.edu#include <list> 431692SN/A#include <string> 441366SN/A 451310SN/A/** 461310SN/A * A simple port for interfacing objects that basically have only 472901SN/A * functional memory behavior (e.g. I/O devices) to the memory system. 483170SN/A * Both timing and functional accesses are implemented in terms of 493170SN/A * atomic accesses. A derived port class thus only needs to provide 501530SN/A * recvAtomic() to support all memory access modes. 513620SN/A * 523617SN/A * The tricky part is handling recvTiming(), where the response must 533617SN/A * be scheduled separately via a later call to sendTiming(). This 543617SN/A * feature is handled by scheduling an internal event that calls 553617SN/A * sendTiming() after a delay, and optionally rescheduling the 563617SN/A * response if it is nacked. 573584SN/A */ 583584SN/Aclass SimpleTimingPort : public Port 593584SN/A{ 603584SN/A protected: 613584SN/A /** A deferred packet, buffered to transmit later. */ 623584SN/A class DeferredPacket { 633584SN/A public: 643584SN/A Tick tick; ///< The tick when the packet is ready to transmit 653584SN/A PacketPtr pkt; ///< Pointer to the packet to transmit 661445SN/A DeferredPacket(Tick t, PacketPtr p) 671445SN/A : tick(t), pkt(p) 681310SN/A {} 691310SN/A }; 701310SN/A 711310SN/A typedef std::list<DeferredPacket> DeferredPacketList; 721310SN/A typedef std::list<DeferredPacket>::iterator DeferredPacketIterator; 731310SN/A 741310SN/A /** A list of outgoing timing response packets that haven't been 751310SN/A * serviced yet. */ 761310SN/A DeferredPacketList transmitList; 773878SN/A 783878SN/A /** This function attempts to send deferred packets. Scheduled to 791310SN/A * be called in the future via SendEvent. */ 801369SN/A void processSendEvent(); 811310SN/A 821634SN/A /** 834167SN/A * This class is used to implemented sendTiming() with a delay. When 844167SN/A * a delay is requested a the event is scheduled if it isn't already. 852998SN/A * When the event time expires it attempts to send the packet. 862998SN/A * If it cannot, the packet sent when recvRetry() is called. 872998SN/A **/ 882998SN/A Event *sendEvent; 892998SN/A 902998SN/A /** If we need to drain, keep the drain event around until we're done 912998SN/A * here.*/ 922998SN/A Event *drainEvent; 932998SN/A 942998SN/A /** Remember whether we're awaiting a retry from the bus. */ 952998SN/A bool waitingOnRetry; 962998SN/A 972998SN/A /** Check the list of buffered packets against the supplied 982998SN/A * functional request. */ 992998SN/A bool checkFunctional(PacketPtr funcPkt); 1002998SN/A 1012998SN/A /** Check whether we have a packet ready to go on the transmit list. */ 1022998SN/A bool deferredPacketReady() 1032998SN/A { return !transmitList.empty() && transmitList.front().tick <= curTick(); } 1042998SN/A 1053017SN/A Tick deferredPacketReadyTime() 1062998SN/A { return transmitList.empty() ? MaxTick : transmitList.front().tick; } 107 108 void 109 schedSendEvent(Tick when) 110 { 111 if (waitingOnRetry) { 112 assert(!sendEvent->scheduled()); 113 return; 114 } 115 116 if (!sendEvent->scheduled()) { 117 schedule(sendEvent, when); 118 } else if (sendEvent->when() > when) { 119 reschedule(sendEvent, when); 120 } 121 } 122 123 124 /** Schedule a sendTiming() event to be called in the future. 125 * @param pkt packet to send 126 * @param absolute time (in ticks) to send packet 127 */ 128 void schedSendTiming(PacketPtr pkt, Tick when); 129 130 /** Attempt to send the packet at the head of the deferred packet 131 * list. Caller must guarantee that the deferred packet list is 132 * non-empty and that the head packet is scheduled for curTick() (or 133 * earlier). 134 */ 135 void sendDeferredPacket(); 136 137 /** This function is notification that the device should attempt to send a 138 * packet again. */ 139 virtual void recvRetry(); 140 141 /** Implemented using recvAtomic(). */ 142 void recvFunctional(PacketPtr pkt); 143 144 /** Implemented using recvAtomic(). */ 145 bool recvTiming(PacketPtr pkt); 146 147 /** 148 * Simple ports generally don't care about any status 149 * changes... can always override this in cases where that's not 150 * true. */ 151 virtual void recvStatusChange(Status status) { } 152 153 154 public: 155 SimpleTimingPort(std::string pname, MemObject *_owner); 156 ~SimpleTimingPort(); 157 158 /** Hook for draining timing accesses from the system. The 159 * associated SimObject's drain() functions should be implemented 160 * something like this when this class is used: 161 \code 162 PioDevice::drain(Event *de) 163 { 164 unsigned int count; 165 count = SimpleTimingPort->drain(de); 166 if (count) 167 changeState(Draining); 168 else 169 changeState(Drained); 170 return count; 171 } 172 \endcode 173 */ 174 unsigned int drain(Event *de); 175}; 176 177#endif // __MEM_TPORT_HH__ 178