src/mem/tport.hh

   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 /**
  32  * @file
  33  * Implement a port which adds simple support of a sendTiming() function that
  34  * takes a delay. In this way the * device can immediatly call
  35  * sendTiming(pkt, time) after processing a request and the request will be
  36  * handled by the port even if the port bus the device connects to is blocked.
  37  */
  38
  39 /** recvTiming and drain should be implemented something like this when this
  40  * class is used.
  41
  42 bool
  43 PioPort::recvTiming(Packet *pkt)
  44 {
  45     if (pkt->result == Packet::Nacked) {
  46         resendNacked(pkt);
  47     } else {
  48         Tick latency = device->recvAtomic(pkt);
  49         // turn packet around to go back to requester
  50         pkt->makeTimingResponse();
  51         sendTiming(pkt, latency);
  52     }
  53     return true;
  54 }
  55
  56 PioDevice::drain(Event *de)
  57 {
  58     unsigned int count;
  59     count = SimpleTimingPort->drain(de);
  60     if (count)
  61         changeState(Draining);
  62     else
  63         changeState(Drained);
  64     return count;
  65 }
  66 */
  67
  68 #ifndef __MEM_TPORT_HH__
  69 #define __MEM_TPORT_HH__
  70
  71 #include "mem/port.hh"
  72 #include "sim/eventq.hh"
  73 #include <list>
  74 #include <string>
  75
  76 class SimpleTimingPort : public Port
  77 {
  78   protected:
  79     /** A list of outgoing timing response packets that haven't been serviced
  80      * yet. */
  81     std::list<Packet*> transmitList;
  82     /**
  83      * This class is used to implemented sendTiming() with a delay. When a delay
  84      * is requested a new event is created. When the event time expires it
  85      * attempts to send the packet. If it cannot, the packet is pushed onto the
  86      * transmit list to be sent when recvRetry() is called. */
  87     class SendEvent : public Event
  88     {
  89         SimpleTimingPort *port;
  90         Packet *packet;
  91
  92         SendEvent(SimpleTimingPort *p, Packet *pkt, Tick t)
  93             : Event(&mainEventQueue), port(p), packet(pkt)
  94         { setFlags(AutoDelete); schedule(curTick + t); }
  95
  96         virtual void process();
  97
  98         virtual const char *description()
  99         { return "Future scheduled sendTiming event"; }
 100
 101         friend class SimpleTimingPort;
 102     };
 103
 104
 105     /** Number of timing requests that are emulating the device timing before
 106      * attempting to end up on the bus.
 107      */
 108     int outTiming;
 109
 110     /** If we need to drain, keep the drain event around until we're done
 111      * here.*/
 112     Event *drainEvent;
 113
 114     /** Schedule a sendTiming() event to be called in the future. */
 115     void sendTiming(Packet *pkt, Tick time)
 116     { outTiming++; new SimpleTimingPort::SendEvent(this, pkt, time); }
 117
 118     /** This function is notification that the device should attempt to send a
 119      * packet again. */
 120     virtual void recvRetry();
 121
 122     void resendNacked(Packet *pkt);
 123   public:
 124
 125     SimpleTimingPort(std::string pname)
 126         : Port(pname), outTiming(0), drainEvent(NULL)
 127     {}
 128
 129     unsigned int drain(Event *de);
 130
 131     friend class SimpleTimingPort::SendEvent;
 132 };
 133
 134 #endif // __MEM_TPORT_HH__