mem: Edit proto Packet and enhance the python script

This patch changes the decode script to output the optional fields of
the proto message Packet, namely id and flags. The flags field is set
by the communication monitor.

The id field is useful for CPU trace experiments, e.g. linking the
fetch side to decode side. It had to be renamed because it clashes
with a built in python function id() for getting the "identity" of an
object.

This patch also takes a few common function definitions out from the
multiple scripts and adds them to a protolib python module.

util/encode_packet_trace.py

@@ -35,37 +35,7 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #
-# Copyright 2008 Google Inc.  All rights reserved.
-# http://code.google.com/p/protobuf/
-#
-# 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 Google Inc. 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: Andreas Hansson
-#
 
 # This script is used to migrate ASCII packet traces to the protobuf
 # format currently used in gem5. It assumes that protoc has been
@@ -83,7 +53,7 @@
 # This script can of course also be used as a template to convert
 # other trace formats into the gem5 protobuf format
 
-import struct
+import protolib
 import sys
 
 # Import the packet proto definitions. If they are not found, attempt
@@ -110,28 +80,6 @@ except:
         print "Failed to import packet proto definitions"
         exit(-1)
 
-def EncodeVarint(out_file, value):
-  """
-  The encoding of the Varint32 is copied from
-  google.protobuf.internal.encoder and is only repeated here to
-  avoid depending on the internal functions in the library.
-  """
-  bits = value & 0x7f
-  value >>= 7
-  while value:
-    out_file.write(struct.pack('<B', 0x80|bits))
-    bits = value & 0x7f
-    value >>= 7
-  out_file.write(struct.pack('<B', bits))
-
-def encodeMessage(out_file, message):
-    """
-    Encoded a message with the length prepended as a 32-bit varint.
-    """
-    out = message.SerializeToString()
-    EncodeVarint(out_file, len(out))
-    out_file.write(out)
-
 def main():
     if len(sys.argv) != 3:
         print "Usage: ", sys.argv[0], " <ASCII input> <protobuf output>"
@@ -158,7 +106,7 @@ def main():
     header.obj_id = "Converted ASCII trace " + sys.argv[1]
     # Assume the default tick rate
     header.tick_freq = 1000000000
-    encodeMessage(proto_out, header)
+    protolib.encodeMessage(proto_out, header)
 
     # For each line in the ASCII trace, create a packet message and
     # write it to the encoded output
@@ -170,7 +118,7 @@ def main():
         packet.cmd = 1 if cmd == 'r' else 4
         packet.addr = long(addr)
         packet.size = int(size)
-        encodeMessage(proto_out, packet)
+        protolib.encodeMessage(proto_out, packet)
 
     # We're done
     ascii_in.close()