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/*
* 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
*/
#ifndef __MEM_PACKET_QUEUE_HH__
#define __MEM_PACKET_QUEUE_HH__
/**
* @file
* Declaration of a simple PacketQueue that is associated with
* a port on which it attempts to send packets according to the time
* stamp given to them at insertion. The packet queue is responsible
* for the flow control of the port, but relies on the module
* notifying the queue when a transfer ends.
*/
#include <list>
#include "mem/port.hh"
#include "sim/eventq.hh"
/**
* A packet queue is a class that holds deferred packets and later
* sends them using the associated slave port or master port.
*/
class PacketQueue
{
private:
/** A deferred packet, buffered to transmit later. */
class DeferredPacket {
public:
Tick tick; ///< The tick when the packet is ready to transmit
PacketPtr pkt; ///< Pointer to the packet to transmit
DeferredPacket(Tick t, PacketPtr p)
: tick(t), pkt(p)
{}
};
typedef std::list<DeferredPacket> DeferredPacketList;
typedef std::list<DeferredPacket>::iterator DeferredPacketIterator;
/** A list of outgoing timing response packets that haven't been
* serviced yet. */
DeferredPacketList transmitList;
/** The manager which is used for the event queue */
EventManager& em;
/** Label to use for print request packets label stack. */
const std::string label;
/** This function attempts to send deferred packets. Scheduled to
* be called in the future via SendEvent. */
void processSendEvent();
/**
* Event used to call processSendEvent.
**/
EventWrapper<PacketQueue, &PacketQueue::processSendEvent> sendEvent;
/** If we need to drain, keep the drain event around until we're done
* here.*/
Event *drainEvent;
protected:
/** The port used to send the packets. */
Port& port;
/** Remember whether we're awaiting a retry from the bus. */
bool waitingOnRetry;
/** Check whether we have a packet ready to go on the transmit list. */
bool deferredPacketReady()
{ return !transmitList.empty() && transmitList.front().tick <= curTick(); }
Tick deferredPacketReadyTime()
{ return transmitList.empty() ? MaxTick : transmitList.front().tick; }
/**
* Attempt to send the packet at the head of the transmit
* list. Caller must guarantee that the list is non-empty and that
* the head packet is scheduled for curTick() (or earlier). Note
* that a subclass of the PacketQueue can override this method and
* thus change the behaviour (as done by the cache).
*/
virtual void sendDeferredPacket();
/**
* Attempt to send the packet at the front of the transmit list,
* and set waitingOnRetry accordingly. The packet is temporarily
* taken off the list, but put back at the front if not
* successfully sent.
*/
void trySendTiming();
/**
* Based on the transmit list, or the provided time, schedule a
* send event if there are packets to send. If we are idle and
* asked to drain then do so.
*
* @param time an alternative time for the next send event
*/
void scheduleSend(Tick time = MaxTick);
/**
* Simple ports are generally used as slave ports (i.e. the
* respond to requests) and thus do not expect to receive any
* range changes (as the neighbouring port has a master role and
* do not have any address ranges. A subclass can override the
* default behaviuor if needed.
*/
virtual void recvRangeChange() { }
public:
/**
* Create a packet queue, linked to an event manager, a port used
* to send the packets, and potentially give it a label that will
* be used for functional print request packets.
*
* @param _em Event manager used for scheduling this queue
* @param _port Port used to send the packets
* @param _label Label to push on the label stack for print request packets
*/
PacketQueue(EventManager& _em, Port& _port,
const std::string _label = "PacketQueue");
/**
* Virtual desctructor since the class may be used as a base class.
*/
virtual ~PacketQueue();
/**
* Provide a name to simplify debugging. Base it on the port.
*
* @return A complete name, appended to module and port
*/
const std::string name() const { return port.name() + "-queue"; }
/** Check the list of buffered packets against the supplied
* functional request. */
bool checkFunctional(PacketPtr pkt);
/**
* Schedule a send even if not already waiting for a retry. If the
* requested time is before an already scheduled send event it
* will be rescheduled.
*
* @param when
*/
void schedSendEvent(Tick when);
/**
* Add a packet to the transmit list, and ensure that a
* processSendEvent is called in the future.
*
* @param pkt Packet to send
* @param when Absolute time (in ticks) to send packet
*/
void schedSendTiming(PacketPtr pkt, Tick when);
/**
* Used by a port to notify the queue that a retry was received
* and that the queue can proceed and retry sending the packet
* that caused the wait.
*/
void retry();
/**
* Hook for draining the packet queue.
*
* @param de An event which is used to signal back to the caller
* @return A number indicating how many times process will be called
*/
unsigned int drain(Event *de);
};
#endif // __MEM_TPORT_HH__
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