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# Copyright (c) 2016 Cisco and/or its affiliates.
# 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.
"""Utils for MAP feature."""
def map_port_ranges(psid, length, offset=6):
"""Return list of port ranges for given PSID in tuple <min, max>.
:param psid: PSID.
:param length: PSID length.
:param offset: PSID offset.
:type psid: int
:type length: int
:type offset: int
:return: List of (min, max) port range tuples inclusive.
:rtype: list
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-----------+-----------+-------+
Ports in | A | PSID | j |
the CE port set | > 0 | | |
+-----------+-----------+-------+
| a bits | k bits |m bits |
"""
port_field_len = 16
port_field_min = int('0x0000', 16)
port_field_max = int('0xffff', 16)
a = offset
k = length
m = port_field_len - offset - length
km = k + m
j_max = port_field_max >> a + k
port_ranges = []
for A in range(1, (port_field_max >> km) + 1):
port_ranges.append((((A << k) | psid) << m,
((A << k) | psid) << m | j_max))
return port_ranges
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