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Diffstat (limited to 'src/mem/packet_queue.hh')
| -rw-r--r-- | src/mem/packet_queue.hh | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/src/mem/packet_queue.hh b/src/mem/packet_queue.hh new file mode 100644 index 000000000..ac868802b --- /dev/null +++ b/src/mem/packet_queue.hh @@ -0,0 +1,218 @@ +/* + * 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__ |