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, 19 insertions, 26 deletions

diff --git a/src/mem/bridge.cc b/src/mem/bridge.cc
index 0733b6ea8..ebb37e792 100644
--- a/src/mem/bridge.cc
+++ b/src/mem/bridge.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011 ARM Limited
+ * Copyright (c) 2011-2012 ARM Limited
  * All rights reserved
  *
  * The license below extends only to copyright in the software and shall
@@ -59,7 +59,7 @@ Bridge::BridgeSlavePort::BridgeSlavePort(const std::string &_name,
                                          int _delay, int _nack_delay,
                                          int _resp_limit,
                                          std::vector<Range<Addr> > _ranges)
-    : Port(_name, _bridge), bridge(_bridge), masterPort(_masterPort),
+    : SlavePort(_name, _bridge), bridge(_bridge), masterPort(_masterPort),
       delay(_delay), nackDelay(_nack_delay),
       ranges(_ranges.begin(), _ranges.end()),
       outstandingResponses(0), inRetry(false),
@@ -71,7 +71,7 @@ Bridge::BridgeMasterPort::BridgeMasterPort(const std::string &_name,
                                            Bridge* _bridge,
                                            BridgeSlavePort& _slavePort,
                                            int _delay, int _req_limit)
-    : Port(_name, _bridge), bridge(_bridge), slavePort(_slavePort),
+    : MasterPort(_name, _bridge), bridge(_bridge), slavePort(_slavePort),
       delay(_delay), inRetry(false), reqQueueLimit(_req_limit),
       sendEvent(*this)
 {
@@ -88,19 +88,25 @@ Bridge::Bridge(Params *p)
         panic("No support for acknowledging writes\n");
 }
 
-Port*
-Bridge::getPort(const std::string &if_name, int idx)
+MasterPort&
+Bridge::getMasterPort(const std::string &if_name, int idx)
 {
-    if (if_name == "slave")
-        return &slavePort;
-    else if (if_name == "master")
-        return &masterPort;
-    else {
-        panic("Bridge %s has no port named %s\n", name(), if_name);
-        return NULL;
-    }
+    if (if_name == "master")
+        return masterPort;
+    else
+        // pass it along to our super class
+        return MemObject::getMasterPort(if_name, idx);
 }
 
+SlavePort&
+Bridge::getSlavePort(const std::string &if_name, int idx)
+{
+    if (if_name == "slave")
+        return slavePort;
+    else
+        // pass it along to our super class
+        return MemObject::getSlavePort(if_name, idx);
+}
 
 void
 Bridge::init()
@@ -473,19 +479,6 @@ Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt)
     return found;
 }
 
-/** Function called by the port when the bridge is receiving a range change.*/
-void
-Bridge::BridgeMasterPort::recvRangeChange()
-{
-    // no need to forward as the bridge has a fixed set of ranges
-}
-
-void
-Bridge::BridgeSlavePort::recvRangeChange()
-{
-    // is a slave port so do nothing
-}
-
 AddrRangeList
 Bridge::BridgeSlavePort::getAddrRanges()
 {