lib/dpid: dpid formatter/parser

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

ryu/lib/dpid.py

@@ -0,0 +1,30 @@
+# Copyright (C) 2012 Nippon Telegraph and Telephone Corporation.
+# Copyright (C) 2012 Isaku Yamahata <yamahata at private email ne jp>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Internal representation of datapath id is quad int
+# string representation is in hex without '0x'
+
+_DPID_LEN = 16
+_DPID_FMT = '%0' + str(_DPID_LEN) + 'x'
+
+
+def dpid_to_str(dpid):
+    return _DPID_FMT % dpid
+
+
+def str_to_dpid(dpid_str):
+    assert len(dpid_str) == _DPID_LEN
+    return int(dpid_str, 16)