68 lines
2.2 KiB
Python
68 lines
2.2 KiB
Python
# This file is a part of sedbgmux, an open source DebugMux client.
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# Copyright (c) 2022 Vadim Yanitskiy <axilirator@gmail.com>
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#
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# SPDX-License-Identifier: GPL-3.0-or-later
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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import logging as log
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from construct import Container, Int16ul
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from proto import DbgMuxFrame
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class DbgMuxPeer:
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def __init__(self, sl):
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self.tx_count: int = 0
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self.rx_count: int = 0
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self._sl = sl
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def send(self, msg_type: DbgMuxFrame.MsgType, msg_data: bytes = b'') -> None:
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c = Container({
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'TxCount' : (self.tx_count + 1) % 256,
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'RxCount' : self.rx_count % 256,
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'MsgType' : msg_type,
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'MsgData' : msg_data,
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'FCS' : 0 # Calculated below
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})
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# ACK is a bit special
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if msg_type == DbgMuxFrame.MsgType.Ack:
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c['TxCount'] = 0xf1
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# There is a Checksum construct, but it requires all checksummed fields
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# to be wrapped into an additional RawCopy construct. This is ugly and
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# inconvinient from the API point of view, so we calculate the FCS manually:
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frame = DbgMuxFrame.Frame.build(c)[:-2] # strip b'\x00\x00'
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c['FCS'] = DbgMuxFrame.fcs_func(frame)
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log.debug('Tx frame (Ns=%d, Nr=%d, fcs=0x%04x) %s %s',
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c['TxCount'], c['RxCount'], c['FCS'],
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c['MsgType'], c['MsgData'].hex())
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self._sl.write(frame + Int16ul.build(c['FCS']))
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# ACK is not getting accounted
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if msg_type != DbgMuxFrame.MsgType.Ack:
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self.tx_count += 1
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def recv(self) -> Container:
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c = DbgMuxFrame.Frame.parse_stream(self._sl)
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log.debug('Rx frame (Ns=%d, Nr=%d, fcs=0x%04x) %s %s',
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c['TxCount'], c['RxCount'], c['FCS'],
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c['MsgType'], c['MsgData'].hex())
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self.rx_count += 1
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return c
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