tport.cc revision 4490:f9d3db907eec 
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    while (i != end) {
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        i++;
51    }
52}
53
54void
55SimpleTimingPort::recvFunctional(PacketPtr pkt)
56{
57    checkFunctional(pkt);
58
59    // Just do an atomic access and throw away the returned latency
60    if (pkt->result != Packet::Success)
61        recvAtomic(pkt);
62}
63
64bool
65SimpleTimingPort::recvTiming(PacketPtr pkt)
66{
67    // If the device is only a slave, it should only be sending
68    // responses, which should never get nacked.  There used to be
69    // code to hanldle nacks here, but I'm pretty sure it didn't work
70    // correctly with the drain code, so that would need to be fixed
71    // if we ever added it back.
72    assert(pkt->result != Packet::Nacked);
73    Tick latency = recvAtomic(pkt);
74    // turn packet around to go back to requester if response expected
75    if (pkt->needsResponse()) {
76        pkt->makeTimingResponse();
77        sendTiming(pkt, latency);
78    }
79    else if (pkt->cmd != MemCmd::UpgradeReq) {
80        delete pkt->req;
81        delete pkt;
82    }
83    return true;
84}
85
86void
87SimpleTimingPort::recvRetry()
88{
89    assert(!transmitList.empty());
90    if (Port::sendTiming(transmitList.front().pkt)) {
91        transmitList.pop_front();
92        DPRINTF(Bus, "No Longer waiting on retry\n");
93        if (!transmitList.empty()) {
94            Tick time = transmitList.front().tick;
95            sendEvent->schedule(time <= curTick ? curTick+1 : time);
96        }
97    }
98
99    if (transmitList.empty() && drainEvent) {
100        drainEvent->process();
101        drainEvent = NULL;
102    }
103}
104
105void
106SimpleTimingPort::sendTiming(PacketPtr pkt, Tick time)
107{
108    // Nothing is on the list: add it and schedule an event
109    if (transmitList.empty()) {
110        assert(!sendEvent->scheduled());
111        sendEvent->schedule(curTick+time);
112        transmitList.push_back(DeferredPacket(time+curTick, pkt));
113        return;
114    }
115
116    // something is on the list and this belongs at the end
117    if (time+curTick >= transmitList.back().tick) {
118        transmitList.push_back(DeferredPacket(time+curTick, pkt));
119        return;
120    }
121    // Something is on the list and this belongs somewhere else
122    DeferredPacketIterator i = transmitList.begin();
123    DeferredPacketIterator end = transmitList.end();
124    bool done = false;
125
126    while (i != end && !done) {
127        if (time+curTick < i->tick) {
128            if (i == transmitList.begin()) {
129                //Inserting at begining, reschedule
130                sendEvent->reschedule(time+curTick);
131            }
132            transmitList.insert(i, DeferredPacket(time+curTick, pkt));
133            done = true;
134        }
135        i++;
136    }
137    assert(done);
138}
139
140void
141SimpleTimingPort::processSendEvent()
142{
143    assert(transmitList.size());
144    assert(transmitList.front().tick <= curTick);
145    if (Port::sendTiming(transmitList.front().pkt)) {
146        //send successful, remove packet
147        transmitList.pop_front();
148        if (!transmitList.empty()) {
149            Tick time = transmitList.front().tick;
150            sendEvent->schedule(time <= curTick ? curTick+1 : time);
151        }
152        if (transmitList.empty() && drainEvent) {
153            drainEvent->process();
154            drainEvent = NULL;
155        }
156        return;
157    }
158    // send unsuccessful (due to flow control).  Will get retry
159    // callback later; save for then if not already
160    DPRINTF(Bus, "Waiting on retry\n");
161}
162
163
164unsigned int
165SimpleTimingPort::drain(Event *de)
166{
167    if (transmitList.size() == 0)
168        return 0;
169    drainEvent = de;
170    return 1;
171}
172