summaryrefslogtreecommitdiff
path: root/src/mem/tport.cc
blob: 61f9e143ccc8e2b06f748d98537b899854641eed (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
/*
 * Copyright (c) 2006 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Ali Saidi
 */

#include "mem/tport.hh"

using namespace std;

SimpleTimingPort::SimpleTimingPort(string pname, MemObject *_owner)
    : Port(pname, _owner), sendEvent(0), drainEvent(NULL),
      waitingOnRetry(false)
{
    sendEvent =  new EventWrapper<SimpleTimingPort,
        &SimpleTimingPort::processSendEvent>(this);
}

SimpleTimingPort::~SimpleTimingPort()
{
    delete sendEvent;
}

bool
SimpleTimingPort::checkFunctional(PacketPtr pkt)
{
    DeferredPacketIterator i = transmitList.begin();
    DeferredPacketIterator end = transmitList.end();

    for (; i != end; ++i) {
        PacketPtr target = i->pkt;
        // If the target contains data, and it overlaps the
        // probed request, need to update data
        if (pkt->checkFunctional(target)) {
            return true;
        }
    }

    return false;
}

void
SimpleTimingPort::recvFunctional(PacketPtr pkt)
{
    if (!checkFunctional(pkt)) {
        // Just do an atomic access and throw away the returned latency
        recvAtomic(pkt);
    }
}

bool
SimpleTimingPort::recvTiming(PacketPtr pkt)
{
    // If the device is only a slave, it should only be sending
    // responses, which should never get nacked.  There used to be
    // code to hanldle nacks here, but I'm pretty sure it didn't work
    // correctly with the drain code, so that would need to be fixed
    // if we ever added it back.

    if (pkt->memInhibitAsserted()) {
        // snooper will supply based on copy of packet
        // still target's responsibility to delete packet
        delete pkt;
        return true;
    }

    bool needsResponse = pkt->needsResponse();
    Tick latency = recvAtomic(pkt);
    // turn packet around to go back to requester if response expected
    if (needsResponse) {
        // recvAtomic() should already have turned packet into
        // atomic response
        assert(pkt->isResponse());
        schedSendTiming(pkt, curTick() + latency);
    } else {
        delete pkt;
    }

    return true;
}


void
SimpleTimingPort::schedSendTiming(PacketPtr pkt, Tick when)
{
    assert(when > curTick());
    assert(when < curTick() + SimClock::Int::ms);

    // Nothing is on the list: add it and schedule an event
    if (transmitList.empty() || when < transmitList.front().tick) {
        transmitList.push_front(DeferredPacket(when, pkt));
        schedSendEvent(when);
        return;
    }

    // list is non-empty & this belongs at the end
    if (when >= transmitList.back().tick) {
        transmitList.push_back(DeferredPacket(when, pkt));
        return;
    }

    // this belongs in the middle somewhere
    DeferredPacketIterator i = transmitList.begin();
    i++; // already checked for insertion at front
    DeferredPacketIterator end = transmitList.end();

    for (; i != end; ++i) {
        if (when < i->tick) {
            transmitList.insert(i, DeferredPacket(when, pkt));
            return;
        }
    }
    assert(false); // should never get here
}


void
SimpleTimingPort::sendDeferredPacket()
{
    assert(deferredPacketReady());
    // take packet off list here; if recvTiming() on the other side
    // calls sendTiming() back on us (like SimpleTimingCpu does), then
    // we get confused by having a non-active packet on transmitList
    DeferredPacket dp = transmitList.front();
    transmitList.pop_front();
    bool success = sendTiming(dp.pkt);

    if (success) {
        if (!transmitList.empty() && !sendEvent->scheduled()) {
            Tick time = transmitList.front().tick;
            schedule(sendEvent, time <= curTick() ? curTick()+1 : time);
        }

        if (transmitList.empty() && drainEvent && !sendEvent->scheduled()) {
            drainEvent->process();
            drainEvent = NULL;
        }
    } else {
        // Unsuccessful, need to put back on transmitList.  Callee
        // should not have messed with it (since it didn't accept that
        // packet), so we can just push it back on the front.
        assert(!sendEvent->scheduled());
        transmitList.push_front(dp);
    }

    waitingOnRetry = !success;

    if (waitingOnRetry) {
        DPRINTF(Bus, "Send failed, waiting on retry\n");
    }
}


void
SimpleTimingPort::recvRetry()
{
    DPRINTF(Bus, "Received retry\n");
    assert(waitingOnRetry);
    sendDeferredPacket();
}


void
SimpleTimingPort::processSendEvent()
{
    assert(!waitingOnRetry);
    sendDeferredPacket();
}


unsigned int
SimpleTimingPort::drain(Event *de)
{
    if (transmitList.size() == 0 && !sendEvent->scheduled())
        return 0;
    drainEvent = de;
    return 1;
}