MEM: Introduce the master/slave port sub-classes in C++

This patch introduces the notion of a master and slave port in the C++
code, thus bringing the previous classification from the Python
classes into the corresponding simulation objects and memory objects.

The patch enables us to classify behaviours into the two bins and add
assumptions and enfore compliance, also simplifying the two
interfaces. As a starting point, isSnooping is confined to a master
port, and getAddrRanges to slave ports. More of these specilisations
are to come in later patches.

The getPort function is not getMasterPort and getSlavePort, and
returns a port reference rather than a pointer as NULL would never be
a valid return value. The default implementation of these two
functions is placed in MemObject, and calls fatal.

The one drawback with this specific patch is that it requires some
code duplication, e.g. QueuedPort becomes QueuedMasterPort and
QueuedSlavePort, and BusPort becomes BusMasterPort and BusSlavePort
(avoiding multiple inheritance). With the later introduction of the
port interfaces, moving the functionality outside the port itself, a
lot of the duplicated code will disappear again.

1 files changed, 81 insertions, 22 deletions

diff --git a/src/mem/bus.hh b/src/mem/bus.hh
index 4ea92308a..e79e9df9e 100644
--- a/src/mem/bus.hh
+++ b/src/mem/bus.hh
@@ -40,6 +40,7 @@
  * Authors: Ron Dreslinski
  *          Ali Saidi
  *          Andreas Hansson
+ *          William Wang
  */
 
 /**
@@ -65,21 +66,85 @@
 
 class Bus : public MemObject
 {
-    /** Declaration of the buses port type, one will be instantiated for each
-        of the interfaces connecting to the bus. */
-    class BusPort : public Port
+    /**
+     * Declaration of the bus slave port type, one will be
+     * instantiated for each of the master interfaces connecting to
+     * the bus.
+     */
+    class BusSlavePort : public SlavePort
+    {
+      private:
+        /** A pointer to the bus to which this port belongs. */
+        Bus *bus;
+
+        /** A id to keep track of the interface ID of this port. */
+        int id;
+
+      public:
+
+        /** Constructor for the BusSlavePort.*/
+        BusSlavePort(const std::string &_name, Bus *_bus, int _id)
+            : SlavePort(_name, _bus), bus(_bus), id(_id)
+        { }
+
+        int getId() const { return id; }
+
+      protected:
+
+        /** When reciving a timing request from the peer port (at id),
+            pass it to the bus. */
+        virtual bool recvTiming(PacketPtr pkt)
+        { pkt->setSrc(id); return bus->recvTiming(pkt); }
+
+        /** When reciving a Atomic requestfrom the peer port (at id),
+            pass it to the bus. */
+        virtual Tick recvAtomic(PacketPtr pkt)
+        { pkt->setSrc(id); return bus->recvAtomic(pkt); }
+
+        /** When reciving a Functional requestfrom the peer port (at id),
+            pass it to the bus. */
+        virtual void recvFunctional(PacketPtr pkt)
+        { pkt->setSrc(id); bus->recvFunctional(pkt); }
+
+        /** When reciving a retry from the peer port (at id),
+            pass it to the bus. */
+        virtual void recvRetry()
+        { bus->recvRetry(id); }
+
+        // This should return all the 'owned' addresses that are
+        // downstream from this bus, yes?  That is, the union of all
+        // the 'owned' address ranges of all the other interfaces on
+        // this bus...
+        virtual AddrRangeList getAddrRanges()
+        { return bus->getAddrRanges(id); }
+
+        // Ask the bus to ask everyone on the bus what their block size is and
+        // take the max of it. This might need to be changed a bit if we ever
+        // support multiple block sizes.
+        virtual unsigned deviceBlockSize() const
+        { return bus->findBlockSize(id); }
+
+    };
+
+    /**
+     * Declaration of the bus master port type, one will be
+     * instantiated for each of the slave interfaces connecting to the
+     * bus.
+     */
+    class BusMasterPort : public MasterPort
     {
+      private:
         /** A pointer to the bus to which this port belongs. */
         Bus *bus;
 
-        /** A id to keep track of the intercafe ID this port is connected to. */
+        /** A id to keep track of the interface ID of this port. */
         int id;
 
       public:
 
-        /** Constructor for the BusPort.*/
-        BusPort(const std::string &_name, Bus *_bus, int _id)
-            : Port(_name, _bus), bus(_bus), id(_id)
+        /** Constructor for the BusMasterPort.*/
+        BusMasterPort(const std::string &_name, Bus *_bus, int _id)
+            : MasterPort(_name, _bus), bus(_bus), id(_id)
         { }
 
         int getId() const { return id; }
@@ -90,7 +155,7 @@ class Bus : public MemObject
          *
          * @return a boolean that is true if this port is snooping
          */
-        virtual bool isSnooping()
+        virtual bool isSnooping() const
         { return bus->isSnooping(id); }
 
       protected:
@@ -120,13 +185,6 @@ class Bus : public MemObject
         virtual void recvRetry()
         { bus->recvRetry(id); }
 
-        // This should return all the 'owned' addresses that are
-        // downstream from this bus, yes?  That is, the union of all
-        // the 'owned' address ranges of all the other interfaces on
-        // this bus...
-        virtual AddrRangeList getAddrRanges()
-        { return bus->getAddrRanges(id); }
-
         // Ask the bus to ask everyone on the bus what their block size is and
         // take the max of it. This might need to be changed a bit if we ever
         // support multiple block sizes.
@@ -151,8 +209,8 @@ class Bus : public MemObject
 
     AddrRangeList defaultRange;
 
-    typedef std::vector<BusPort*>::iterator SnoopIter;
-    std::vector<BusPort*> snoopPorts;
+    typedef std::vector<BusSlavePort*>::iterator SnoopIter;
+    std::vector<BusSlavePort*> snoopPorts;
 
     /** Function called by the port when the bus is recieving a Timing
       transaction.*/
@@ -250,7 +308,7 @@ class Bus : public MemObject
      *
      * @return a boolean indicating if this port is snooping or not
      */
-    bool isSnooping(int id);
+    bool isSnooping(int id) const;
 
     /** Calculate the timing parameters for the packet.  Updates the
      * firstWordTime and finishTime fields of the packet object.
@@ -292,9 +350,9 @@ class Bus : public MemObject
     // interfaces vector
     unsigned int nbrMasterPorts;
 
-    /** An ordered vector of pointers to the peer port interfaces
-        connected to this bus.*/
-    std::vector<BusPort*> interfaces;
+    /** The master and slave ports of the bus */
+    std::vector<BusSlavePort*> slavePorts;
+    std::vector<BusMasterPort*> masterPorts;
 
     /** An array of pointers to ports that retry should be called on because the
      * original send failed for whatever reason.*/
@@ -338,7 +396,8 @@ class Bus : public MemObject
   public:
 
     /** A function used to return the port associated with this bus object. */
-    virtual Port *getPort(const std::string &if_name, int idx = -1);
+    virtual MasterPort& getMasterPort(const std::string& if_name, int idx = -1);
+    virtual SlavePort& getSlavePort(const std::string& if_name, int idx = -1);
 
     virtual void init();
     virtual void startup();