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/*
* Copyright (c) 2016-2020 Advanced Micro Devices, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. 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.
*
* 3. Neither the name of the copyright holder 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 HOLDER 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.
*/
#ifndef __MEM_TOKEN_PORT_HH__
#define __MEM_TOKEN_PORT_HH__
#include "mem/port.hh"
#include "sim/clocked_object.hh"
namespace gem5
{
class TokenManager;
class TokenResponsePort;
class TokenRequestPort : public RequestPort
{
private:
/* Manager to track tokens between this token port pair. */
TokenManager *tokenManager;
public:
TokenRequestPort(const std::string& name, SimObject* owner,
PortID id = InvalidPortID) :
RequestPort(name, id), tokenManager(nullptr)
{ }
/**
* Bind this request port to response port. Called by the response port in
* this token implementation.
*/
void bind(Port &peer) override;
/**
* Unbind port. Handled by response port in token implementation.
*/
void unbind() override {}
/**
* Receive tokens returned by the response port. This increments the number
* or available tokens across the port.
*/
void recvTokens(int num_tokens);
/**
* Query if there are at least num_tokens tokens available to acquire.
*/
bool haveTokens(int num_tokens);
/**
* Acquire tokens by decrementing the number of available tokens across
* the port. This does the opposite of recvTokens.
*/
void acquireTokens(int num_tokens);
/**
* Specify a token manger, which will handle tracking of tokens for a
* TokenRequestPort/ResponseRequestPort pair.
*/
void setTokenManager(TokenManager *_tokenManager);
};
class TokenResponsePort : public ResponsePort
{
private:
TokenRequestPort *tokenRequestPort;
std::deque<PacketPtr> respQueue;
void recvRespRetry() override;
public:
TokenResponsePort(const std::string& name,
PortID id = InvalidPortID) :
ResponsePort(name, id), tokenRequestPort(nullptr)
{ }
~TokenResponsePort() { }
/**
* Bind this response port to a request port. This also does the mirror
* action and binds the request port to the response port as well as
* binding the base class types.
*/
void bind(Port &peer) override;
/**
* Unbind this response port and associated request port.
*/
void unbind() override;
/**
* Return num_tokens tokens back to the request port.
*/
void sendTokens(int num_tokens);
bool sendTimingResp(PacketPtr pkt);
/* There is no storage here so the packet will not be found. */
bool trySatisfyFunctional(PacketPtr) { return false; }
};
class TokenManager
{
protected:
/* Maximum tokens possible */
int maxTokens;
/* Number of currently available tokens */
int availableTokens;
public:
TokenManager(int init_tokens);
~TokenManager() { }
/**
* Return the maximum possible tokens.
*/
int getMaxTokenCount() const;
/**
* Increment the number of available tokens by num_tokens.
*/
void recvTokens(int num_tokens);
/**
* Query is num_tokens tokens are available.
*/
bool haveTokens(int num_tokens);
/**
* Decrement the number of available tokens by num_tokens.
*/
void acquireTokens(int num_tokens);
};
} // namespace gem5
#endif