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/*
* 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"
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.
assert(pkt->isRequest());
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->req;
delete pkt;
}
return true;
}
void
SimpleTimingPort::schedSendTiming(PacketPtr pkt, Tick when)
{
assert(when > curTick);
// 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 and this is not the head, so event should
// already be scheduled
assert(waitingOnRetry ||
(sendEvent->scheduled() && sendEvent->when() <= when));
// 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;
sendEvent->schedule(time <= curTick ? curTick+1 : time);
}
if (transmitList.empty() && drainEvent) {
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)
return 0;
drainEvent = de;
return 1;
}
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