tport.cc revision 3091:dba513d68c16 
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    // just do an atomic access and throw away the returned latency
37    recvAtomic(pkt);
38}
39
40bool
41SimpleTimingPort::recvTiming(Packet *pkt)
42{
43    // If the device is only a slave, it should only be sending
44    // responses, which should never get nacked.  There used to be
45    // code to hanldle nacks here, but I'm pretty sure it didn't work
46    // correctly with the drain code, so that would need to be fixed
47    // if we ever added it back.
48    assert(pkt->result != Packet::Nacked);
49    Tick latency = recvAtomic(pkt);
50    // turn packet around to go back to requester
51    pkt->makeTimingResponse();
52    sendTimingLater(pkt, latency);
53    return true;
54}
55
56void
57SimpleTimingPort::recvRetry()
58{
59    bool result = true;
60    while (result && transmitList.size()) {
61        result = sendTiming(transmitList.front());
62        if (result)
63            transmitList.pop_front();
64    }
65    if (transmitList.size() == 0 && drainEvent) {
66        drainEvent->process();
67        drainEvent = NULL;
68    }
69}
70
71void
72SimpleTimingPort::SendEvent::process()
73{
74    port->outTiming--;
75    assert(port->outTiming >= 0);
76    if (port->sendTiming(packet)) {
77        // send successfule
78        if (port->transmitList.size() == 0 && port->drainEvent) {
79            port->drainEvent->process();
80            port->drainEvent = NULL;
81        }
82    } else {
83        // send unsuccessful (due to flow control).  Will get retry
84        // callback later; save for then.
85        port->transmitList.push_back(packet);
86    }
87}
88
89
90unsigned int
91SimpleTimingPort::drain(Event *de)
92{
93    if (outTiming == 0 && transmitList.size() == 0)
94        return 0;
95    drainEvent = de;
96    return 1;
97}
98