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(Packet *pkt)
  35 {
  36     // just do an atomic access and throw away the returned latency
  37     recvAtomic(pkt);
  38 }
  39
  40 bool
  41 SimpleTimingPort::recvTiming(Packet *pkt)
  42 {
  43     // If the device is only a slave, it should only be sending
  44     // responses, which should never get nacked.  There used to be
  45     // code to hanldle nacks here, but I'm pretty sure it didn't work
  46     // correctly with the drain code, so that would need to be fixed
  47     // if we ever added it back.
  48     assert(pkt->result != Packet::Nacked);
  49     Tick latency = recvAtomic(pkt);
  50     // turn packet around to go back to requester if response expected
  51     if (pkt->needsResponse()) {
  52         pkt->makeTimingResponse();
  53         sendTimingLater(pkt, latency);
  54     }
  55     return true;
  56 }
  57
  58 void
  59 SimpleTimingPort::recvRetry()
  60 {
  61     bool result = true;
  62
  63     assert(transmitList.size());
  64     while (result && transmitList.size()) {
  65         result = sendTiming(transmitList.front());
  66         if (result)
  67             transmitList.pop_front();
  68     }
  69     if (transmitList.size() == 0 && drainEvent) {
  70         drainEvent->process();
  71         drainEvent = NULL;
  72     }
  73 }
  74
  75 void
  76 SimpleTimingPort::SendEvent::process()
  77 {
  78     port->outTiming--;
  79     assert(port->outTiming >= 0);
  80     if (port->transmitList.size()) {
  81         port->transmitList.push_back(packet);
  82     } else if (port->sendTiming(packet)) {
  83         // send successful
  84         if (port->transmitList.size() == 0 && port->drainEvent) {
  85             port->drainEvent->process();
  86             port->drainEvent = NULL;
  87         }
  88     } else {
  89         // send unsuccessful (due to flow control).  Will get retry
  90         // callback later; save for then.
  91         port->transmitList.push_back(packet);
  92     }
  93 }
  94
  95
  96 unsigned int
  97 SimpleTimingPort::drain(Event *de)
  98 {
  99     if (outTiming == 0 && transmitList.size() == 0)
 100         return 0;
 101     drainEvent = de;
 102     return 1;
 103 }