tport.cc revision 4626 
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::checkFunctional(PacketPtr pkt)
35{
36    DeferredPacketIterator i = transmitList.begin();
37    DeferredPacketIterator end = transmitList.end();
38
39    for (; i != end; ++i) {
40        PacketPtr target = i->pkt;
41        // If the target contains data, and it overlaps the
42        // probed request, need to update data
43        if (target->intersect(pkt)) {
44            if (!fixPacket(pkt, target)) {
45                // fixPacket returns true for continue, false for done
46                return;
47            }
48        }
49    }
50}
51
52void
53SimpleTimingPort::recvFunctional(PacketPtr pkt)
54{
55    checkFunctional(pkt);
56
57    // Just do an atomic access and throw away the returned latency
58    if (pkt->result != Packet::Success)
59        recvAtomic(pkt);
60}
61
62bool
63SimpleTimingPort::recvTiming(PacketPtr pkt)
64{
65    // If the device is only a slave, it should only be sending
66    // responses, which should never get nacked.  There used to be
67    // code to hanldle nacks here, but I'm pretty sure it didn't work
68    // correctly with the drain code, so that would need to be fixed
69    // if we ever added it back.
70    assert(pkt->isRequest());
71    assert(pkt->result == Packet::Unknown);
72    bool needsResponse = pkt->needsResponse();
73    Tick latency = recvAtomic(pkt);
74    // turn packet around to go back to requester if response expected
75    if (needsResponse) {
76        // recvAtomic() should already have turned packet into atomic response
77        assert(pkt->isResponse());
78        pkt->convertAtomicToTimingResponse();
79        schedSendTiming(pkt, curTick + latency);
80    } else {
81        delete pkt->req;
82        delete pkt;
83    }
84    return true;
85}
86
87
88void
89SimpleTimingPort::schedSendTiming(PacketPtr pkt, Tick when)
90{
91    assert(when > curTick);
92
93    // Nothing is on the list: add it and schedule an event
94    if (transmitList.empty()) {
95        assert(!sendEvent->scheduled());
96        sendEvent->schedule(when);
97        transmitList.push_back(DeferredPacket(when, pkt));
98        return;
99    }
100
101    // something is on the list and this belongs at the end
102    if (when >= transmitList.back().tick) {
103        transmitList.push_back(DeferredPacket(when, pkt));
104        return;
105    }
106    // Something is on the list and this belongs somewhere else
107    DeferredPacketIterator i = transmitList.begin();
108    DeferredPacketIterator end = transmitList.end();
109
110    for (; i != end; ++i) {
111        if (when < i->tick) {
112            if (i == transmitList.begin()) {
113                //Inserting at begining, reschedule
114                sendEvent->reschedule(when);
115            }
116            transmitList.insert(i, DeferredPacket(when, pkt));
117            return;
118        }
119    }
120    assert(false); // should never get here
121}
122
123
124void
125SimpleTimingPort::sendDeferredPacket()
126{
127    assert(deferredPacketReady());
128    bool success = sendTiming(transmitList.front().pkt);
129
130    if (success) {
131        //send successful, remove packet
132        transmitList.pop_front();
133        if (!transmitList.empty()) {
134            Tick time = transmitList.front().tick;
135            sendEvent->schedule(time <= curTick ? curTick+1 : time);
136        }
137
138        if (transmitList.empty() && drainEvent) {
139            drainEvent->process();
140            drainEvent = NULL;
141        }
142    }
143
144    waitingOnRetry = !success;
145
146    if (waitingOnRetry) {
147        DPRINTF(Bus, "Send failed, waiting on retry\n");
148    }
149}
150
151
152void
153SimpleTimingPort::recvRetry()
154{
155    DPRINTF(Bus, "Received retry\n");
156    assert(waitingOnRetry);
157    sendDeferredPacket();
158}
159
160
161void
162SimpleTimingPort::processSendEvent()
163{
164    assert(!waitingOnRetry);
165    sendDeferredPacket();
166}
167
168
169unsigned int
170SimpleTimingPort::drain(Event *de)
171{
172    if (transmitList.size() == 0)
173        return 0;
174    drainEvent = de;
175    return 1;
176}
177