util: Add a utility script for encoding packet traces

This patch adds a simple Python script that reads a simple ASCII trace
format and encodes it as protobuf output compatible with the traffic
generator.

The script can also be used as a template for other packet input
formats that should be converted to the gem5 packet protobuf format.

diff --git a/util/encode_packet_trace.py b/util/encode_packet_trace.py
new file mode 100755 (executable)
index 0000000..cbfc7d9
--- /dev/null
+++ b/util/encode_packet_trace.py
@@ -0,0 +1,157 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2013 ARM Limited
+# All rights reserved
+#
+# The license below extends only to copyright in the software and shall
+# not be construed as granting a license to any other intellectual
+# property including but not limited to intellectual property relating
+# to a hardware implementation of the functionality of the software
+# licensed hereunder.  You may use the software subject to the license
+# terms below provided that you ensure that this notice is replicated
+# unmodified and in its entirety in all distributions of the software,
+# modified or unmodified, in source code or in binary form.
+#
+# 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 the copyright holders 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.
+#
+# 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
+# executed and already generated the Python package for the packet
+# messages. This can be done manually using:
+# protoc --python_out=. --proto_path=src/proto src/proto/packet.proto
+#
+# The ASCII trace format uses one line per request on the format cmd,
+# addr, size, tick. For example:
+# r,128,64,4000
+# w,232123,64,500000
+# This trace reads 64 bytes from decimal address 128 at tick 4000,
+# then writes 64 bytes to address 232123 at tick 500000.
+#
+# This script can of course also be used as a template to convert
+# other trace formats into the gem5 protobuf format
+
+import struct
+import sys
+import packet_pb2
+
+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>"
+        exit(-1)
+
+    try:
+        ascii_in = open(sys.argv[1], 'r')
+    except IOError:
+        print "Failed to open ", sys.argv[1], " for reading"
+        exit(-1)
+
+    try:
+        proto_out = open(sys.argv[2], 'wb')
+    except IOError:
+        print "Failed to open ", sys.argv[2], " for writing"
+        exit(-1)
+
+    # Write the magic number in 4-byte Little Endian, similar to what
+    # is done in src/proto/protoio.cc
+    proto_out.write("gem5")
+
+    # Add the packet header
+    header = packet_pb2.PacketHeader()
+    header.obj_id = "Converted ASCII trace " + sys.argv[1]
+    # Assume the default tick rate
+    header.tick_freq = 1000000000
+    encodeMessage(proto_out, header)
+
+    # For each line in the ASCII trace, create a packet message and
+    # write it to the encoded output
+    for line in ascii_in:
+        cmd, addr, size, tick = line.split(',')
+        packet = packet_pb2.Packet()
+        packet.tick = long(tick)
+        # ReadReq is 1 and WriteReq is 4 in src/mem/packet.hh Command enum
+        packet.cmd = 1 if cmd == 'r' else 4
+        packet.addr = long(addr)
+        packet.size = int(size)
+        encodeMessage(proto_out, packet)
+
+    # We're done
+    ascii_in.close()
+    proto_out.close()
+
+if __name__ == "__main__":
+    main()