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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright 2020 Daniel Estevez <daniel@destevez.net>
#
# This file is part of gr-satellites
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
import struct
import datetime
import types
from .imagereceiver import ImageReceiver
from ..telemetry.csp import CSPHeader
class ImageReceiverDSAT(ImageReceiver):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self._dsat_reset_segments()
def _dsat_reset_segments(self):
self._dsat_old_offset = 0
self._dsat_current_segment = 0
self._dsat_current_segment_size = None
def _dsat_segment_size(self, chunk):
return struct.unpack('>I', chunk[-4:])[0]
def chunk_offset(self, chunk):
offset = struct.unpack('>I', chunk[-8:-4])[0]
# handle offset rollover
if self._dsat_old_offset > offset:
self.log('D-SAT offset rollover')
if self._dsat_current_segment_size is None:
self.log('unknown last segment size, '
'taking from current chunk')
self._dsat_current_segment_size = (
self._dsat_segment_size(chunk))
self._dsat_current_segment += self._dsat_current_segment_size
self.log(f'current segment now {self._dsat_current_segment}')
self._dsat_old_offset = offset
self._dsat_current_segment_size = self._dsat_segment_size(chunk)
return self._dsat_current_segment + offset
def chunk_data(self, chunk):
return chunk[4:-8]
def filename(self, fid):
return f'{fid}.jpg'
def parse_chunk(self, chunk):
if len(chunk) <= 15+8:
return None
header = CSPHeader.parse(chunk)
# destination port 30 is used for JPEG blocks
if header.destination_port != 30:
return None
return chunk
def _watch_file_announcements(self, chunk):
if len(chunk) < 25:
return
header = CSPHeader.parse(chunk)
# destination port 12 is used for announcements
if header.destination_port != 12:
return
timestamp = datetime.datetime.utcfromtimestamp(
struct.unpack('<i', chunk[4:8])[0])
fid = struct.unpack('<I', chunk[8:12])[0]
# next 12 bytes are for GPS position
length = struct.unpack('<I', chunk[21:25])[0]
self.log(f'image {fid} announced. Length {length}. '
f'Timestamp {timestamp}')
# hook lambda functions for file id and size
self.file_id = types.MethodType(lambda self, chunk: fid, self)
self.file_size = types.MethodType(lambda self, chunk: length, self)
self._dsat_reset_segments()
def push_chunk(self, chunk):
# hook the file announcement watch here
self._watch_file_announcements(chunk)
super().push_chunk(chunk)
dsat = ImageReceiverDSAT
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