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+/*
+ * Copyright (c) 2003-2005 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: Erik Hallnor
+ */
+
+/** @file
+ * Declaration of a structure to manage MSHRs.
+ */
+
+#ifndef __MSHR_QUEUE_HH__
+#define __MSHR_QUEUE_HH__
+
+#include <vector>
+#include "mem/cache/miss/mshr.hh"
+
+/**
+ * A Class for maintaining a list of pending and allocated memory requests.
+ */
+class MSHRQueue {
+ private:
+ /** MSHR storage. */
+ MSHR* registers;
+ /** Holds pointers to all allocated MSHRs. */
+ MSHR::List allocatedList;
+ /** Holds pointers to MSHRs that haven't been sent to the bus. */
+ MSHR::List pendingList;
+ /** Holds non allocated MSHRs. */
+ MSHR::List freeList;
+
+ // Parameters
+ /**
+ * The total number of MSHRs in this queue. This number is set as the
+ * number of MSHRs requested plus (numReserve - 1). This allows for
+ * the same number of effective MSHRs while still maintaining the reserve.
+ */
+ const int numMSHRs;
+
+ /**
+ * The number of MSHRs to hold in reserve. This is needed because copy
+ * operations can allocate upto 4 MSHRs at one time.
+ */
+ const int numReserve;
+
+ public:
+ /** The number of allocated MSHRs. */
+ int allocated;
+ /** The number of MSHRs that have been forwarded to the bus. */
+ int inServiceMSHRs;
+ /** The number of targets waiting for response. */
+ int allocatedTargets;
+
+ /**
+ * Create a queue with a given number of MSHRs.
+ * @param num_mshrs The number of MSHRs in this queue.
+ * @param reserve The minimum number of MSHRs needed to satisfy any access.
+ */
+ MSHRQueue(int num_mshrs, int reserve = 1);
+
+ /** Destructor */
+ ~MSHRQueue();
+
+ /**
+ * Find the first MSHR that matches the provide address and asid.
+ * @param addr The address to find.
+ * @param asid The address space id.
+ * @return Pointer to the matching MSHR, null if not found.
+ */
+ MSHR* findMatch(Addr addr, int asid) const;
+
+ /**
+ * Find and return all the matching MSHRs in the provided vector.
+ * @param addr The address to find.
+ * @param asid The address space ID.
+ * @param matches The vector to return pointers to the matching MSHRs.
+ * @return True if any matches are found, false otherwise.
+ * @todo Typedef the vector??
+ */
+ bool findMatches(Addr addr, int asid, std::vector<MSHR*>& matches) const;
+
+ /**
+ * Find any pending requests that overlap the given request.
+ * @param req The request to find.
+ * @return A pointer to the earliest matching MSHR.
+ */
+ MSHR* findPending(Packet * &pkt) const;
+
+ /**
+ * Allocates a new MSHR for the request and size. This places the request
+ * as the first target in the MSHR.
+ * @param req The request to handle.
+ * @param size The number in bytes to fetch from memory.
+ * @return The a pointer to the MSHR allocated.
+ *
+ * @pre There are free MSHRs.
+ */
+ MSHR* allocate(Packet * &pkt, int size = 0);
+
+ /**
+ * Allocate a read request for the given address, and places the given
+ * target on the target list.
+ * @param addr The address to fetch.
+ * @param asid The address space for the fetch.
+ * @param size The number of bytes to request.
+ * @param target The first target for the request.
+ * @return Pointer to the new MSHR.
+ */
+ MSHR* allocateFetch(Addr addr, int asid, int size, Packet * &target);
+
+ /**
+ * Allocate a target list for the given address.
+ * @param addr The address to fetch.
+ * @param asid The address space for the fetch.
+ * @param size The number of bytes to request.
+ * @return Pointer to the new MSHR.
+ */
+ MSHR* allocateTargetList(Addr addr, int asid, int size);
+
+ /**
+ * Removes the given MSHR from the queue. This places the MSHR on the
+ * free list.
+ * @param mshr
+ */
+ void deallocate(MSHR* mshr);
+
+ /**
+ * Allocates a target to the given MSHR. Used to keep track of the number
+ * of outstanding targets.
+ * @param mshr The MSHR to allocate the target to.
+ * @param req The target request.
+ */
+ void allocateTarget(MSHR* mshr, Packet * &pkt)
+ {
+ mshr->allocateTarget(pkt);
+ allocatedTargets += 1;
+ }
+
+ /**
+ * Remove a MSHR from the queue. Returns an iterator into the allocatedList
+ * for faster squash implementation.
+ * @param mshr The MSHR to remove.
+ * @return An iterator to the next entry in the allocatedList.
+ */
+ MSHR::Iterator deallocateOne(MSHR* mshr);
+
+ /**
+ * Moves the MSHR to the front of the pending list if it is not in service.
+ * @param mshr The mshr to move.
+ */
+ void moveToFront(MSHR *mshr);
+
+ /**
+ * Mark the given MSHR as in service. This removes the MSHR from the
+ * pendingList. Deallocates the MSHR if it does not expect a response.
+ * @param mshr The MSHR to mark in service.
+ */
+ void markInService(MSHR* mshr);
+
+ /**
+ * Mark an in service mshr as pending, used to resend a request.
+ * @param mshr The MSHR to resend.
+ * @param cmd The command to resend.
+ */
+ void markPending(MSHR* mshr, Packet::Command cmd);
+
+ /**
+ * Squash outstanding requests with the given thread number. If a request
+ * is in service, just squashes the targets.
+ * @param thread_number The thread to squash.
+ */
+ void squash(int thread_number);
+
+ /**
+ * Returns true if the pending list is not empty.
+ * @return True if there are outstanding requests.
+ */
+ bool havePending() const
+ {
+ return !pendingList.empty();
+ }
+
+ /**
+ * Returns true if there are no free MSHRs.
+ * @return True if this queue is full.
+ */
+ bool isFull() const
+ {
+ return (allocated > numMSHRs - numReserve);
+ }
+
+ /**
+ * Returns the request at the head of the pendingList.
+ * @return The next request to service.
+ */
+ Packet * getReq() const
+ {
+ if (pendingList.empty()) {
+ return NULL;
+ }
+ MSHR* mshr = pendingList.front();
+ return mshr->pkt;
+ }
+
+ /**
+ * Returns the number of outstanding targets.
+ * @return the number of allocated targets.
+ */
+ int getAllocatedTargets() const
+ {
+ return allocatedTargets;
+ }
+
+};
+
+#endif //__MSHR_QUEUE_HH__