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https://gitee.com/qpy-solutions/dtu.git
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64 lines
2.0 KiB
Python
64 lines
2.0 KiB
Python
# Copyright (c) Quectel Wireless Solution, Co., Ltd.All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from usr.modules.common import Singleton
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class DtuProtocolData(Singleton):
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def __init__(self):
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self.crc_table = []
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self._create_table()
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def _create_table(self):
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poly = 0xEDB88320
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a = []
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for byte in range(256):
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crc = 0
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for bit in range(8):
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if (byte ^ crc) & 1:
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crc = (crc >> 1) ^ poly
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else:
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crc >>= 1
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byte >>= 1
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a.append(crc)
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self.crc_table = a
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def crc32(self, crc_string):
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value = 0xffffffff
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for ch in crc_string:
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value = self.crc_table[(ord(ch) ^ value) & 0xff] ^ (value >> 8)
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crc_value = str((-1 - value) & 0xffffffff)
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return crc_value
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def package_datas(self, msg_data, topic_id=None, channel_id=None):
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data = []
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msg_length = len(str(msg_data))
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if channel_id is not None:
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data.append(str(channel_id))
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if topic_id is not None:
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data.append(str(topic_id))
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data.append(str(msg_length))
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if len(msg_data) != 0:
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crc32_val = self.crc32(str(msg_data))
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data.append(crc32_val)
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data.append(str(msg_data))
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data_str = ",".join(data)
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ret_bytes = data_str.encode()
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print("ret_bytes:", ret_bytes)
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return ret_bytes
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