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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
* Steve Reinhardt
*/
/**
* @file
* Declaration of a simple bus bridge object with no buffering
*/
#ifndef __MEM_BRIDGE_HH__
#define __MEM_BRIDGE_HH__
#include <string>
#include <list>
#include <inttypes.h>
#include <queue>
#include "mem/mem_object.hh"
#include "mem/packet.hh"
#include "mem/port.hh"
#include "params/Bridge.hh"
#include "sim/eventq.hh"
class Bridge : public MemObject
{
protected:
/** Declaration of the buses port type, one will be instantiated for each
of the interfaces connecting to the bus. */
class BridgePort : public Port
{
/** A pointer to the bridge to which this port belongs. */
Bridge *bridge;
/**
* Pointer to the port on the other side of the bridge
* (connected to the other bus).
*/
BridgePort *otherPort;
/** Minimum delay though this bridge. */
Tick delay;
/** Min delay to respond to a nack. */
Tick nackDelay;
bool fixPartialWrite;
class PacketBuffer : public Packet::SenderState {
public:
Tick ready;
PacketPtr pkt;
Packet::SenderState *origSenderState;
short origSrc;
bool expectResponse;
PacketBuffer(PacketPtr _pkt, Tick t, bool nack = false)
: ready(t), pkt(_pkt),
origSenderState(_pkt->senderState), origSrc(_pkt->getSrc()),
expectResponse(_pkt->needsResponse() && !nack)
{
if (!pkt->isResponse() && !nack && pkt->result != Packet::Nacked)
pkt->senderState = this;
}
void fixResponse(PacketPtr pkt)
{
assert(pkt->senderState == this);
pkt->setDest(origSrc);
pkt->senderState = origSenderState;
}
};
/**
* Outbound packet queue. Packets are held in this queue for a
* specified delay to model the processing delay of the
* bridge.
*/
std::list<PacketBuffer*> sendQueue;
int outstandingResponses;
int queuedRequests;
/** If we're waiting for a retry to happen.*/
bool inRetry;
/** Max queue size for outbound packets */
int reqQueueLimit;
/** Max queue size for reserved responses. */
int respQueueLimit;
/**
* Is this side blocked from accepting outbound packets?
*/
bool respQueueFull();
bool reqQueueFull();
void queueForSendTiming(PacketPtr pkt);
void finishSend(PacketBuffer *buf);
void nackRequest(PacketPtr pkt);
/**
* Handle send event, scheduled when the packet at the head of
* the outbound queue is ready to transmit (for timing
* accesses only).
*/
void trySend();
class SendEvent : public Event
{
BridgePort *port;
public:
SendEvent(BridgePort *p)
: Event(&mainEventQueue), port(p) {}
virtual void process() { port->trySend(); }
virtual const char *description() { return "bridge send event"; }
};
SendEvent sendEvent;
public:
/** Constructor for the BusPort.*/
BridgePort(const std::string &_name, Bridge *_bridge,
BridgePort *_otherPort, int _delay, int _nack_delay,
int _req_limit, int _resp_limit, bool fix_partial_write);
protected:
/** When receiving a timing request from the peer port,
pass it to the bridge. */
virtual bool recvTiming(PacketPtr pkt);
/** When receiving a retry request from the peer port,
pass it to the bridge. */
virtual void recvRetry();
/** When receiving a Atomic requestfrom the peer port,
pass it to the bridge. */
virtual Tick recvAtomic(PacketPtr pkt);
/** When receiving a Functional request from the peer port,
pass it to the bridge. */
virtual void recvFunctional(PacketPtr pkt);
/** When receiving a status changefrom the peer port,
pass it to the bridge. */
virtual void recvStatusChange(Status status);
/** When receiving a address range request the peer port,
pass it to the bridge. */
virtual void getDeviceAddressRanges(AddrRangeList &resp,
bool &snoop);
};
BridgePort portA, portB;
/** If this bridge should acknowledge writes. */
bool ackWrites;
public:
typedef BridgeParams Params;
protected:
Params *_params;
public:
const Params *params() const { return _params; }
/** A function used to return the port associated with this bus object. */
virtual Port *getPort(const std::string &if_name, int idx = -1);
virtual void init();
Bridge(Params *p);
};
#endif //__MEM_BUS_HH__
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