src/mem/tport.cc

   1 /*
   2  * Copyright (c) 2006 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  * Authors: Ali Saidi
  29  */
  30
  31 #include "mem/tport.hh"
  32
  33 void
  34 SimpleTimingPort::recvFunctional(PacketPtr pkt)
  35 {
  36     std::list<std::pair<Tick,PacketPtr> >::iterator i = transmitList.begin();
  37     std::list<std::pair<Tick,PacketPtr> >::iterator end = transmitList.end();
  38     bool notDone = true;
  39
  40     while (i != end && notDone) {
  41         PacketPtr target = i->second;
  42         // If the target contains data, and it overlaps the
  43         // probed request, need to update data
  44         if (target->intersect(pkt))
  45             notDone = fixPacket(pkt, target);
  46
  47         i++;
  48     }
  49
  50     //Then just do an atomic access and throw away the returned latency
  51     if (pkt->result != Packet::Success)
  52         recvAtomic(pkt);
  53 }
  54
  55 bool
  56 SimpleTimingPort::recvTiming(PacketPtr pkt)
  57 {
  58     // If the device is only a slave, it should only be sending
  59     // responses, which should never get nacked.  There used to be
  60     // code to hanldle nacks here, but I'm pretty sure it didn't work
  61     // correctly with the drain code, so that would need to be fixed
  62     // if we ever added it back.
  63     assert(pkt->result != Packet::Nacked);
  64     Tick latency = recvAtomic(pkt);
  65     // turn packet around to go back to requester if response expected
  66     if (pkt->needsResponse()) {
  67         pkt->makeTimingResponse();
  68         sendTiming(pkt, latency);
  69     }
  70     else {
  71         if (pkt->cmd != MemCmd::UpgradeReq)
  72         {
  73             delete pkt->req;
  74             delete pkt;
  75         }
  76     }
  77     return true;
  78 }
  79
  80 void
  81 SimpleTimingPort::recvRetry()
  82 {
  83     assert(!transmitList.empty());
  84     if (Port::sendTiming(transmitList.front().second)) {
  85         transmitList.pop_front();
  86         DPRINTF(Bus, "No Longer waiting on retry\n");
  87         if (!transmitList.empty()) {
  88             Tick time = transmitList.front().first;
  89             sendEvent.schedule(time <= curTick ? curTick+1 : time);
  90         }
  91     }
  92
  93     if (transmitList.empty() && drainEvent) {
  94         drainEvent->process();
  95         drainEvent = NULL;
  96     }
  97 }
  98
  99 void
 100 SimpleTimingPort::sendTiming(PacketPtr pkt, Tick time)
 101 {
 102     // Nothing is on the list: add it and schedule an event
 103     if (transmitList.empty()) {
 104         assert(!sendEvent.scheduled());
 105         sendEvent.schedule(curTick+time);
 106         transmitList.push_back(std::pair<Tick,PacketPtr>(time+curTick,pkt));
 107         return;
 108     }
 109
 110     // something is on the list and this belongs at the end
 111     if (time+curTick >= transmitList.back().first) {
 112         transmitList.push_back(std::pair<Tick,PacketPtr>(time+curTick,pkt));
 113         return;
 114     }
 115     // Something is on the list and this belongs somewhere else
 116     std::list<std::pair<Tick,PacketPtr> >::iterator i = transmitList.begin();
 117     std::list<std::pair<Tick,PacketPtr> >::iterator end = transmitList.end();
 118     bool done = false;
 119
 120     while (i != end && !done) {
 121         if (time+curTick < i->first) {
 122             if (i == transmitList.begin()) {
 123                 //Inserting at begining, reschedule
 124                 sendEvent.reschedule(time+curTick);
 125             }
 126             transmitList.insert(i,std::pair<Tick,PacketPtr>(time+curTick,pkt));
 127             done = true;
 128         }
 129         i++;
 130     }
 131 }
 132
 133 void
 134 SimpleTimingPort::SendEvent::process()
 135 {
 136     assert(port->transmitList.size());
 137     assert(port->transmitList.front().first <= curTick);
 138     if (port->Port::sendTiming(port->transmitList.front().second)) {
 139         //send successful, remove packet
 140         port->transmitList.pop_front();
 141         if (!port->transmitList.empty()) {
 142             Tick time = port->transmitList.front().first;
 143             schedule(time <= curTick ? curTick+1 : time);
 144         }
 145         if (port->transmitList.empty() && port->drainEvent) {
 146             port->drainEvent->process();
 147             port->drainEvent = NULL;
 148         }
 149         return;
 150     }
 151     // send unsuccessful (due to flow control).  Will get retry
 152     // callback later; save for then if not already
 153     DPRINTF(Bus, "Waiting on retry\n");
 154 }
 155
 156
 157 unsigned int
 158 SimpleTimingPort::drain(Event *de)
 159 {
 160     if (transmitList.size() == 0)
 161         return 0;
 162     drainEvent = de;
 163     return 1;
 164 }