cpu: Split the traffic generator into two classes

The traffic generator currently assumes that it is always driven from
a configuration file. Split it into a base class (BaseTrafficGen) that
handles basic packet generation and a derived class that implements
the config handling (TrafficGen).

Change-Id: I9407f04c40ad7e40a263c8d1ef29d37ff8e6f1b4
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11515

src/cpu/testers/traffic_gen/SConscript

@@ -1,6 +1,6 @@
 # -*- mode:python -*-
 
-# Copyright (c) 2012, 2017 ARM Limited
+# Copyright (c) 2012, 2017-2018 ARM Limited
 # All rights reserved.
 #
 # The license below extends only to copyright in the software and shall
@@ -39,19 +39,23 @@
 
 Import('*')
 
+
+Source('base.cc')
+Source('base_gen.cc')
+Source('dram_gen.cc')
+Source('dram_rot_gen.cc')
+Source('exit_gen.cc')
+Source('idle_gen.cc')
+Source('linear_gen.cc')
+Source('random_gen.cc')
+
+DebugFlag('TrafficGen')
+SimObject('BaseTrafficGen.py')
+
 # Only build the traffic generator if we have support for protobuf as the
 # tracing relies on it
 if env['HAVE_PROTOBUF']:
     SimObject('TrafficGen.py')
-
-    Source('base_gen.cc')
-    Source('dram_gen.cc')
-    Source('dram_rot_gen.cc')
-    Source('exit_gen.cc')
-    Source('idle_gen.cc')
-    Source('linear_gen.cc')
-    Source('random_gen.cc')
     Source('trace_gen.cc')
     Source('traffic_gen.cc')
 
-    DebugFlag('TrafficGen')