MEM: Split SimpleTimingPort into PacketQueue and ports

This patch decouples the queueing and the port interactions to
simplify the introduction of the master and slave ports. By separating
the queueing functionality from the port itself, it becomes much
easier to distinguish between master and slave ports, and still retain
the queueing ability for both (without code duplication).

As part of the split into a PacketQueue and a port, there is now also
a hierarchy of two port classes, QueuedPort and SimpleTimingPort. The
QueuedPort is useful for ports that want to leave the packet
transmission of outgoing packets to the queue and is used by both
master and slave ports. The SimpleTimingPort inherits from the
QueuedPort and adds the implemention of recvTiming and recvFunctional
through recvAtomic.

The PioPort and MessagePort are cleaned up as part of the changes.

--HG--
rename : src/mem/tport.cc => src/mem/packet_queue.cc
rename : src/mem/tport.hh => src/mem/packet_queue.hh

1 files changed, 205 insertions, 0 deletions

diff --git a/src/mem/packet_queue.cc b/src/mem/packet_queue.cc
new file mode 100644
index 000000000..29914bea2
--- /dev/null
+++ b/src/mem/packet_queue.cc
@@ -0,0 +1,205 @@
+/*
+ * Copyright (c) 2012 ARM Limited
+ * All rights reserved.
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder.  You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * 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
+ *          Andreas Hansson
+ */
+
+#include "debug/PacketQueue.hh"
+#include "mem/packet_queue.hh"
+
+using namespace std;
+
+PacketQueue::PacketQueue(EventManager& _em, Port& _port,
+                         const std::string _label)
+    : em(_em), label(_label), sendEvent(this), drainEvent(NULL), port(_port),
+      waitingOnRetry(false)
+{
+}
+
+PacketQueue::~PacketQueue()
+{
+}
+
+void
+PacketQueue::retry()
+{
+    DPRINTF(PacketQueue, "Queue %s received retry\n", name());
+    assert(waitingOnRetry);
+    sendDeferredPacket();
+}
+
+bool
+PacketQueue::checkFunctional(PacketPtr pkt)
+{
+    pkt->pushLabel(label);
+
+    DeferredPacketIterator i = transmitList.begin();
+    DeferredPacketIterator end = transmitList.end();
+    bool found = false;
+
+    while (!found && i != end) {
+        // If the buffered packet contains data, and it overlaps the
+        // current packet, then update data
+        found = pkt->checkFunctional(i->pkt);
+        ++i;
+    }
+
+    pkt->popLabel();
+
+    return found;
+}
+
+void
+PacketQueue::schedSendEvent(Tick when)
+{
+    // if we are waiting on a retry, do not schedule a send event, and
+    // instead rely on retry being called
+    if (waitingOnRetry) {
+        assert(!sendEvent.scheduled());
+        return;
+    }
+
+    if (!sendEvent.scheduled()) {
+        em.schedule(&sendEvent, when);
+    } else if (sendEvent.when() > when) {
+        em.reschedule(&sendEvent, when);
+    }
+}
+
+void
+PacketQueue::schedSendTiming(PacketPtr pkt, Tick when)
+{
+    assert(when > curTick());
+
+    // nothing on the list, or earlier than current front element,
+    // schedule an event
+    if (transmitList.empty() || when < transmitList.front().tick) {
+        // note that currently we ignore a potentially outstanding retry
+        // and could in theory put a new packet at the head of the
+        // transmit list before retrying the existing packet
+        transmitList.push_front(DeferredPacket(when, pkt));
+        schedSendEvent(when);
+        return;
+    }
+
+    // list is non-empty and this belongs at the end
+    if (when >= transmitList.back().tick) {
+        transmitList.push_back(DeferredPacket(when, pkt));
+        return;
+    }
+
+    // this belongs in the middle somewhere, insertion sort
+    DeferredPacketIterator i = transmitList.begin();
+    ++i; // already checked for insertion at front
+    while (i != transmitList.end() && when >= i->tick)
+        ++i;
+    transmitList.insert(i, DeferredPacket(when, pkt));
+}
+
+void PacketQueue::trySendTiming()
+{
+    assert(deferredPacketReady());
+
+    // take the next packet off the list here, as we might return to
+    // ourselves through the sendTiming call below
+    DeferredPacket dp = transmitList.front();
+    transmitList.pop_front();
+
+    // attempt to send the packet and remember the outcome
+    waitingOnRetry = !port.sendTiming(dp.pkt);
+
+    if (waitingOnRetry) {
+        // put the packet back at the front of the list (packet should
+        // not have changed since it wasn't accepted)
+        assert(!sendEvent.scheduled());
+        transmitList.push_front(dp);
+    }
+}
+
+void
+PacketQueue::scheduleSend(Tick time)
+{
+    // the next ready time is either determined by the next deferred packet,
+    // or in the cache through the MSHR ready time
+    Tick nextReady = std::min(deferredPacketReadyTime(), time);
+
+    if (nextReady != MaxTick) {
+        // if the sendTiming caused someone else to call our
+        // recvTiming we could already have an event scheduled, check
+        if (!sendEvent.scheduled())
+            em.schedule(&sendEvent, std::max(nextReady, curTick() + 1));
+    } else {
+        // no more to send, so if we're draining, we may be done
+        if (drainEvent && !sendEvent.scheduled()) {
+            drainEvent->process();
+            drainEvent = NULL;
+        }
+    }
+}
+
+void
+PacketQueue::sendDeferredPacket()
+{
+    // try to send what is on the list, this will set waitingOnRetry
+    // accordingly
+    trySendTiming();
+
+    // if we succeeded and are not waiting for a retry, schedule the
+    // next send
+    if (!waitingOnRetry) {
+        scheduleSend();
+    }
+}
+
+void
+PacketQueue::processSendEvent()
+{
+    assert(!waitingOnRetry);
+    sendDeferredPacket();
+}
+
+unsigned int
+PacketQueue::drain(Event *de)
+{
+    if (transmitList.empty() && !sendEvent.scheduled())
+        return 0;
+    drainEvent = de;
+    return 1;
+}