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/*
* Copyright (c) 2017 Jason Lowe-Power
* 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: Jason Lowe-Power
*/
#ifndef __LEARNING_GEM5_PART2_SIMPLE_MEMOBJ_HH__
#define __LEARNING_GEM5_PART2_SIMPLE_MEMOBJ_HH__
#include "mem/port.hh"
#include "params/SimpleMemobj.hh"
#include "sim/sim_object.hh"
/**
* A very simple memory object. Current implementation doesn't even cache
* anything it just forwards requests and responses.
* This memobj is fully blocking (not non-blocking). Only a single request can
* be outstanding at a time.
*/
class SimpleMemobj : public SimObject
{
private:
/**
* Port on the CPU-side that receives requests.
* Mostly just forwards requests to the owner.
* Part of a vector of ports. One for each CPU port (e.g., data, inst)
*/
class CPUSidePort : public SlavePort
{
private:
/// The object that owns this object (SimpleMemobj)
SimpleMemobj *owner;
/// True if the port needs to send a retry req.
bool needRetry;
/// If we tried to send a packet and it was blocked, store it here
PacketPtr blockedPacket;
public:
/**
* Constructor. Just calls the superclass constructor.
*/
CPUSidePort(const std::string& name, SimpleMemobj *owner) :
SlavePort(name, owner), owner(owner), needRetry(false),
blockedPacket(nullptr)
{ }
/**
* Send a packet across this port. This is called by the owner and
* all of the flow control is hanled in this function.
*
* @param packet to send.
*/
void sendPacket(PacketPtr pkt);
/**
* Get a list of the non-overlapping address ranges the owner is
* responsible for. All slave ports must override this function
* and return a populated list with at least one item.
*
* @return a list of ranges responded to
*/
AddrRangeList getAddrRanges() const override;
/**
* Send a retry to the peer port only if it is needed. This is called
* from the SimpleMemobj whenever it is unblocked.
*/
void trySendRetry();
protected:
/**
* Receive an atomic request packet from the master port.
* No need to implement in this simple memobj.
*/
Tick recvAtomic(PacketPtr pkt) override
{ panic("recvAtomic unimpl."); }
/**
* Receive a functional request packet from the master port.
* Performs a "debug" access updating/reading the data in place.
*
* @param packet the requestor sent.
*/
void recvFunctional(PacketPtr pkt) override;
/**
* Receive a timing request from the master port.
*
* @param the packet that the requestor sent
* @return whether this object can consume the packet. If false, we
* will call sendRetry() when we can try to receive this
* request again.
*/
bool recvTimingReq(PacketPtr pkt) override;
/**
* Called by the master port if sendTimingResp was called on this
* slave port (causing recvTimingResp to be called on the master
* port) and was unsuccesful.
*/
void recvRespRetry() override;
};
/**
* Port on the memory-side that receives responses.
* Mostly just forwards requests to the owner
*/
class MemSidePort : public MasterPort
{
private:
/// The object that owns this object (SimpleMemobj)
SimpleMemobj *owner;
/// If we tried to send a packet and it was blocked, store it here
PacketPtr blockedPacket;
public:
/**
* Constructor. Just calls the superclass constructor.
*/
MemSidePort(const std::string& name, SimpleMemobj *owner) :
MasterPort(name, owner), owner(owner), blockedPacket(nullptr)
{ }
/**
* Send a packet across this port. This is called by the owner and
* all of the flow control is hanled in this function.
*
* @param packet to send.
*/
void sendPacket(PacketPtr pkt);
protected:
/**
* Receive a timing response from the slave port.
*/
bool recvTimingResp(PacketPtr pkt) override;
/**
* Called by the slave port if sendTimingReq was called on this
* master port (causing recvTimingReq to be called on the slave
* port) and was unsuccesful.
*/
void recvReqRetry() override;
/**
* Called to receive an address range change from the peer slave
* port. The default implementation ignores the change and does
* nothing. Override this function in a derived class if the owner
* needs to be aware of the address ranges, e.g. in an
* interconnect component like a bus.
*/
void recvRangeChange() override;
};
/**
* Handle the request from the CPU side
*
* @param requesting packet
* @return true if we can handle the request this cycle, false if the
* requestor needs to retry later
*/
bool handleRequest(PacketPtr pkt);
/**
* Handle the respone from the memory side
*
* @param responding packet
* @return true if we can handle the response this cycle, false if the
* responder needs to retry later
*/
bool handleResponse(PacketPtr pkt);
/**
* Handle a packet functionally. Update the data on a write and get the
* data on a read.
*
* @param packet to functionally handle
*/
void handleFunctional(PacketPtr pkt);
/**
* Return the address ranges this memobj is responsible for. Just use the
* same as the next upper level of the hierarchy.
*
* @return the address ranges this memobj is responsible for
*/
AddrRangeList getAddrRanges() const;
/**
* Tell the CPU side to ask for our memory ranges.
*/
void sendRangeChange();
/// Instantiation of the CPU-side ports
CPUSidePort instPort;
CPUSidePort dataPort;
/// Instantiation of the memory-side port
MemSidePort memPort;
/// True if this is currently blocked waiting for a response.
bool blocked;
public:
/** constructor
*/
SimpleMemobj(SimpleMemobjParams *params);
/**
* Get a port with a given name and index. This is used at
* binding time and returns a reference to a protocol-agnostic
* port.
*
* @param if_name Port name
* @param idx Index in the case of a VectorPort
*
* @return A reference to the given port
*/
Port &getPort(const std::string &if_name,
PortID idx=InvalidPortID) override;
};
#endif // __LEARNING_GEM5_PART2_SIMPLE_MEMOBJ_HH__