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, 12 insertions, 9 deletions

diff --git a/src/arch/x86/interrupts.hh b/src/arch/x86/interrupts.hh
index abf3040bd..328e7159d 100644
--- a/src/arch/x86/interrupts.hh
+++ b/src/arch/x86/interrupts.hh
@@ -189,7 +189,7 @@ class Interrupts : public BasicPioDevice, IntDev
     int initialApicId;
 
     // Port for receiving interrupts
-    IntPort intSlavePort;
+    IntSlavePort intSlavePort;
 
   public:
 
@@ -239,17 +239,20 @@ class Interrupts : public BasicPioDevice, IntDev
     AddrRangeList getAddrRanges();
     AddrRangeList getIntAddrRange();
 
-    Port *getPort(const std::string &if_name, int idx = -1)
+    MasterPort &getMasterPort(const std::string &if_name, int idx = -1)
     {
-        // a bit of an odd one since there is now two ports in the
-        // Python class we also need two ports even if they are
-        // identical
         if (if_name == "int_master") {
-            return &intPort;
-        } else if (if_name == "int_slave") {
-            return &intSlavePort;
+            return intMasterPort;
         }
-        return BasicPioDevice::getPort(if_name, idx);
+        return BasicPioDevice::getMasterPort(if_name, idx);
+    }
+
+    SlavePort &getSlavePort(const std::string &if_name, int idx = -1)
+    {
+        if (if_name == "int_slave") {
+            return intSlavePort;
+        }
+        return BasicPioDevice::getSlavePort(if_name, idx);
     }
 
     /*