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/*
* Copyright (c) 2012-2013 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) 2001-2005 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: Ron Dreslinski
* Andreas Hansson
*/
/**
* @file
* SimpleMemory declaration
*/
#ifndef __MEM_SIMPLE_MEMORY_HH__
#define __MEM_SIMPLE_MEMORY_HH__
#include <list>
#include "mem/abstract_mem.hh"
#include "mem/port.hh"
#include "params/SimpleMemory.hh"
/**
* The simple memory is a basic single-ported memory controller with
* a configurable throughput and latency.
*
* @sa \ref gem5MemorySystem "gem5 Memory System"
*/
class SimpleMemory : public AbstractMemory
{
private:
/**
* A deferred packet stores a packet along with its scheduled
* transmission time
*/
class DeferredPacket
{
public:
const Tick tick;
const PacketPtr pkt;
DeferredPacket(PacketPtr _pkt, Tick _tick) : tick(_tick), pkt(_pkt)
{ }
};
class MemoryPort : public SlavePort
{
private:
SimpleMemory& memory;
public:
MemoryPort(const std::string& _name, SimpleMemory& _memory);
protected:
Tick recvAtomic(PacketPtr pkt);
void recvFunctional(PacketPtr pkt);
bool recvTimingReq(PacketPtr pkt);
void recvRespRetry();
AddrRangeList getAddrRanges() const;
};
MemoryPort port;
/**
* Latency from that a request is accepted until the response is
* ready to be sent.
*/
const Tick latency;
/**
* Fudge factor added to the latency.
*/
const Tick latency_var;
/**
* Internal (unbounded) storage to mimic the delay caused by the
* actual memory access. Note that this is where the packet spends
* the memory latency.
*/
std::list<DeferredPacket> packetQueue;
/**
* Bandwidth in ticks per byte. The regulation affects the
* acceptance rate of requests and the queueing takes place after
* the regulation.
*/
const double bandwidth;
/**
* Track the state of the memory as either idle or busy, no need
* for an enum with only two states.
*/
bool isBusy;
/**
* Remember if we have to retry an outstanding request that
* arrived while we were busy.
*/
bool retryReq;
/**
* Remember if we failed to send a response and are awaiting a
* retry. This is only used as a check.
*/
bool retryResp;
/**
* Release the memory after being busy and send a retry if a
* request was rejected in the meanwhile.
*/
void release();
EventFunctionWrapper releaseEvent;
/**
* Dequeue a packet from our internal packet queue and move it to
* the port where it will be sent as soon as possible.
*/
void dequeue();
EventFunctionWrapper dequeueEvent;
/**
* Detemine the latency.
*
* @return the latency seen by the current packet
*/
Tick getLatency() const;
/**
* Upstream caches need this packet until true is returned, so
* hold it for deletion until a subsequent call
*/
std::unique_ptr<Packet> pendingDelete;
public:
SimpleMemory(const SimpleMemoryParams *p);
DrainState drain() override;
Port &getPort(const std::string &if_name,
PortID idx=InvalidPortID) override;
void init() override;
protected:
Tick recvAtomic(PacketPtr pkt);
void recvFunctional(PacketPtr pkt);
bool recvTimingReq(PacketPtr pkt);
void recvRespRetry();
};
#endif //__MEM_SIMPLE_MEMORY_HH__
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