tport.cc revision 3296:58498b71afd8 
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
33void
34SimpleTimingPort::recvFunctional(Packet *pkt)
35{
36    //First check queued events
37    std::list<Packet *>::iterator i = transmitList.begin();
38    std::list<Packet *>::iterator end = transmitList.end();
39    bool cont = true;
40
41    while (i != end && cont) {
42        Packet * target = *i;
43        // If the target contains data, and it overlaps the
44        // probed request, need to update data
45        if (target->intersect(pkt))
46            fixPacket(pkt, target);
47
48    }
49    //Then just do an atomic access and throw away the returned latency
50    if (cont)
51        recvAtomic(pkt);
52}
53
54bool
55SimpleTimingPort::recvTiming(Packet *pkt)
56{
57    // If the device is only a slave, it should only be sending
58    // responses, which should never get nacked.  There used to be
59    // code to hanldle nacks here, but I'm pretty sure it didn't work
60    // correctly with the drain code, so that would need to be fixed
61    // if we ever added it back.
62    assert(pkt->result != Packet::Nacked);
63    Tick latency = recvAtomic(pkt);
64    // turn packet around to go back to requester if response expected
65    if (pkt->needsResponse()) {
66        pkt->makeTimingResponse();
67        sendTimingLater(pkt, latency);
68    }
69    return true;
70}
71
72void
73SimpleTimingPort::recvRetry()
74{
75    assert(outTiming > 0);
76    assert(!transmitList.empty());
77    if (sendTiming(transmitList.front())) {
78        transmitList.pop_front();
79        outTiming--;
80        DPRINTF(Bus, "No Longer waiting on retry\n");
81        if (!transmitList.empty())
82            sendTimingLater(transmitList.front(), 1);
83    }
84
85    if (transmitList.empty() && drainEvent) {
86        drainEvent->process();
87        drainEvent = NULL;
88    }
89}
90
91void
92SimpleTimingPort::SendEvent::process()
93{
94    assert(port->outTiming > 0);
95    if (!port->transmitList.empty() && port->transmitList.front() != packet) {
96        //We are not the head of the list
97        port->transmitList.push_back(packet);
98    } else if (port->sendTiming(packet)) {
99        // send successful
100        if (port->transmitList.size()) {
101            port->transmitList.pop_front();
102            port->outTiming--;
103           if (!port->transmitList.empty())
104                port->sendTimingLater(port->transmitList.front(), 1);
105        }
106        if (port->transmitList.empty() && port->drainEvent) {
107            port->drainEvent->process();
108            port->drainEvent = NULL;
109        }
110    } else {
111        // send unsuccessful (due to flow control).  Will get retry
112        // callback later; save for then if not already
113        DPRINTF(Bus, "Waiting on retry\n");
114        if (!(port->transmitList.front() == packet))
115            port->transmitList.push_back(packet);
116    }
117}
118
119
120unsigned int
121SimpleTimingPort::drain(Event *de)
122{
123    if (outTiming == 0 && transmitList.size() == 0)
124        return 0;
125    drainEvent = de;
126    return 1;
127}
128