FreeDATA/modem/data_frame_factory.py

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from modem_frametypes import FRAME_TYPE as FR_TYPE
import helpers
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import codec2
class DataFrameFactory:
LENGTH_SIG0_FRAME = 14
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LENGTH_SIG1_FRAME = 14
def __init__(self, config):
self.myfullcall = f"{config['STATION']['mycall']}-{config['STATION']['myssid']}"
self.mygrid = config['STATION']['mygrid']
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# table for holding our frame templates
self.template_list = {}
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self._load_broadcast_templates()
self._load_ping_templates()
self._load_fec_templates()
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self._load_arq_templates()
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def _load_broadcast_templates(self):
# cq frame
self.template_list[FR_TYPE.CQ.value] = {
"frame_length": self.LENGTH_SIG0_FRAME,
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"origin": 6,
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"gridsquare": 4
}
# qrv frame
self.template_list[FR_TYPE.QRV.value] = {
"frame_length": self.LENGTH_SIG0_FRAME,
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"origin": 6,
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"gridsquare": 4,
"snr": 1
}
# beacon frame
self.template_list[FR_TYPE.BEACON.value] = {
"frame_length": self.LENGTH_SIG0_FRAME,
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"origin": 6,
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"gridsquare": 4
}
def _load_ping_templates(self):
# ping frame
self.template_list[FR_TYPE.PING.value] = {
"frame_length": self.LENGTH_SIG0_FRAME,
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"destination_crc": 3,
"origin_crc": 3,
"origin": 6
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}
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# ping ack
self.template_list[FR_TYPE.PING_ACK.value] = {
"frame_length": self.LENGTH_SIG0_FRAME,
"destination_crc": 3,
"origin_crc": 3,
"gridsquare": 4,
"snr": 1,
}
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def _load_fec_templates(self):
# fec wakeup frame
self.template_list[FR_TYPE.FEC_WAKEUP.value] = {
"frame_length": self.LENGTH_SIG0_FRAME,
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"origin": 6,
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"mode": 1,
"n_bursts": 1,
}
# fec frame
self.template_list[FR_TYPE.FEC.value] = {
"frame_length": self.LENGTH_SIG0_FRAME,
"data": self.LENGTH_SIG0_FRAME - 1
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}
# fec is writing frame
self.template_list[FR_TYPE.IS_WRITING.value] = {
"frame_length": self.LENGTH_SIG0_FRAME,
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"origin": 6
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}
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def _load_arq_templates(self):
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self.template_list[FR_TYPE.ARQ_SESSION_OPEN.value] = {
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"frame_length": self.LENGTH_SIG0_FRAME,
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"destination_crc": 3,
"origin": 6,
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"session_id": 1,
}
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self.template_list[FR_TYPE.ARQ_SESSION_OPEN_ACK.value] = {
"frame_length": self.LENGTH_SIG0_FRAME,
"session_id": 1,
"origin": 6,
"destination_crc": 3,
"version": 1,
"snr": 1,
}
self.template_list[FR_TYPE.ARQ_SESSION_INFO.value] = {
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"frame_length": self.LENGTH_SIG0_FRAME,
"session_id": 1,
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"total_length": 4,
"total_crc": 4,
"snr": 1,
}
self.template_list[FR_TYPE.ARQ_SESSION_INFO_ACK.value] = {
"frame_length": self.LENGTH_SIG0_FRAME,
"session_id": 1,
"total_crc": 4,
"snr": 1,
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"speed_level": 1,
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"frames_per_burst": 1,
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}
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# arq burst frame
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self.template_list[FR_TYPE.BURST_FRAME.value] = {
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"frame_length": None,
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"session_id": 1,
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"offset": 4,
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"data": "dynamic",
}
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# arq burst ack
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self.template_list[FR_TYPE.BURST_ACK.value] = {
"frame_length": self.LENGTH_SIG1_FRAME,
"session_id": 1,
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"offset":4,
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"speed_level": 1,
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"frames_per_burst": 1,
"snr": 1,
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}
# arq burst nack
self.template_list[FR_TYPE.BURST_NACK.value] = {
"frame_length": self.LENGTH_SIG1_FRAME,
"session_id": 1,
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"offset":4,
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"speed_level": 1,
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"frames_per_burst": 1,
"snr": 1,
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}
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def construct(self, frametype, content, frame_length = LENGTH_SIG1_FRAME):
frame_template = self.template_list[frametype.value]
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if isinstance(frame_template["frame_length"], int):
length = frame_template["frame_length"]
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else:
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length = frame_length
frame = bytearray(frame_length)
frame[:1] = bytes([frametype.value])
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buffer_position = 1
for key, item_length in frame_template.items():
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if key == "frame_length":
continue
if not isinstance(item_length, int):
item_length = len(content[key])
if buffer_position + item_length > frame_length:
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raise OverflowError("Frame data overflow!")
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frame[buffer_position: buffer_position + item_length] = content[key]
buffer_position += item_length
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return frame
def deconstruct(self, frame):
buffer_position = 1
# Extract frametype and get the corresponding template
frametype = int.from_bytes(frame[:1], "big")
frame_template = self.template_list.get(frametype)
if not frame_template:
# Handle the case where the frame type is not recognized
raise ValueError(f"Unknown frame type: {frametype}")
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extracted_data = {"frame_type": FR_TYPE(frametype).name, "frame_type_int": frametype}
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for key, item_length in frame_template.items():
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if key == "frame_length":
continue
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# data is always on the last payload slots
if item_length in ["dynamic"] and key in["data"]:
data = frame[buffer_position:]
item_length = len(data)
else:
data = frame[buffer_position: buffer_position + item_length]
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# Process the data based on the key
if key in ["origin", "destination"]:
extracted_data[key] = helpers.bytes_to_callsign(data).decode()
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elif key in ["origin_crc", "destination_crc", "total_crc"]:
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extracted_data[key] = data.hex()
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elif key == "gridsquare":
extracted_data[key] = helpers.decode_grid(data)
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elif key in ["session_id", "speed_level",
"frames_per_burst", "version",
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"snr", "offset", "total_length"]:
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extracted_data[key] = int.from_bytes(data, 'big')
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else:
extracted_data[key] = data
buffer_position += item_length
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return extracted_data
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def get_bytes_per_frame(self, mode: codec2.FREEDV_MODE) -> int:
freedv = codec2.open_instance(mode.value)
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bytes_per_frame = int(codec2.api.freedv_get_bits_per_modem_frame(freedv) / 8)
return bytes_per_frame
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def get_available_data_payload_for_mode(self, type: FR_TYPE, mode:codec2.FREEDV_MODE):
whole_frame_length = self.get_bytes_per_frame(mode)
available = whole_frame_length
for field, length in self.template_list[type.value].items():
if field != 'frame_length' and isinstance(length, int):
available -= length
return available
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def build_ping(self, destination):
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payload = {
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"destination_crc": helpers.get_crc_24(destination),
"origin_crc": helpers.get_crc_24(self.myfullcall),
"origin": helpers.callsign_to_bytes(self.myfullcall),
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}
return self.construct(FR_TYPE.PING, payload)
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def build_ping_ack(self, destination, snr):
payload = {
"destination_crc": helpers.get_crc_24(destination),
"origin_crc": helpers.get_crc_24(self.myfullcall),
"gridsquare": helpers.encode_grid(self.mygrid),
"snr": helpers.snr_to_bytes(snr)
}
return self.construct(FR_TYPE.PING_ACK, payload)
def build_cq(self):
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payload = {
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"origin": helpers.callsign_to_bytes(self.myfullcall),
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"gridsquare": helpers.encode_grid(self.mygrid)
}
return self.construct(FR_TYPE.CQ, payload)
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def build_qrv(self, snr):
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payload = {
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"origin": helpers.callsign_to_bytes(self.myfullcall),
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"gridsquare": helpers.encode_grid(self.mygrid),
"snr": helpers.snr_to_bytes(snr)
}
return self.construct(FR_TYPE.QRV, payload)
def build_beacon(self):
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payload = {
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"origin": helpers.callsign_to_bytes(self.myfullcall),
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"gridsquare": helpers.encode_grid(self.mygrid)
}
return self.construct(FR_TYPE.BEACON, payload)
def build_fec_is_writing(self):
payload = {
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"origin": helpers.callsign_to_bytes(self.myfullcall),
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}
return self.construct(FR_TYPE.IS_WRITING, payload)
def build_fec_wakeup(self, mode):
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mode_int = codec2.freedv_get_mode_value_by_name(mode)
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payload = {
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"origin": helpers.callsign_to_bytes(self.myfullcall),
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"mode": bytes([mode_int]),
"n_bursts": bytes([1]) # n payload bursts,
}
return self.construct(FR_TYPE.FEC_WAKEUP, payload)
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def build_fec(self, mode, payload):
mode_int = codec2.freedv_get_mode_value_by_name(mode)
payload_per_frame = codec2.get_bytes_per_frame(mode_int) - 2
fec_payload_length = payload_per_frame - 1
fec_frame = bytearray(payload_per_frame)
fec_frame[:1] = bytes([FR_TYPE.FEC.value])
fec_frame[1:payload_per_frame] = bytes(payload[:fec_payload_length])
return fec_frame
def build_test(self):
test_frame = bytearray(126)
test_frame[:1] = bytes([FR_TYPE.TEST_FRAME.value])
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return test_frame
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def build_arq_session_open(self, destination, session_id):
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payload = {
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"destination_crc": helpers.get_crc_24(destination),
"origin": helpers.callsign_to_bytes(self.myfullcall),
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"session_id": session_id.to_bytes(1, 'big'),
}
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return self.construct(FR_TYPE.ARQ_SESSION_OPEN, payload)
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def build_arq_session_open_ack(self, session_id, destination, version, snr):
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payload = {
"session_id": session_id.to_bytes(1, 'big'),
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"origin": helpers.callsign_to_bytes(self.myfullcall),
"destination_crc": helpers.get_crc_24(destination),
"version": bytes([version]),
"snr": snr.to_bytes(1, 'big'),
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}
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return self.construct(FR_TYPE.ARQ_SESSION_OPEN_ACK, payload)
def build_arq_session_info(self, session_id: int, total_length: int, total_crc: bytes, snr):
payload = {
"session_id": session_id.to_bytes(1, 'big'),
"total_length": total_length.to_bytes(4, 'big'),
"total_crc": total_crc,
"snr": snr.to_bytes(1, 'big'),
}
return self.construct(FR_TYPE.ARQ_SESSION_INFO, payload)
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def build_arq_session_info_ack(self, session_id, total_crc, snr, speed_level, frames_per_burst):
payload = {
"frame_length": self.LENGTH_SIG0_FRAME,
"session_id": session_id.to_bytes(1, 'big'),
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"total_crc": bytes.fromhex(total_crc),
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"snr": snr.to_bytes(1, 'big'),
"speed_level": speed_level.to_bytes(1, 'big'),
"frames_per_burst": frames_per_burst.to_bytes(1, 'big'),
}
return self.construct(FR_TYPE.ARQ_SESSION_INFO_ACK, payload)
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def build_arq_burst_frame(self, freedv_mode: codec2.FREEDV_MODE, session_id: int, offset: int, data: bytes):
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payload = {
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"session_id": session_id.to_bytes(1, 'big'),
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"offset": offset.to_bytes(4, 'big'),
"data": data,
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}
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return self.construct(FR_TYPE.BURST_FRAME, payload, self.get_bytes_per_frame(freedv_mode))
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def build_arq_burst_ack(self, session_id: bytes, offset, speed_level: int,
frames_per_burst: int, snr: int):
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payload = {
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"session_id": session_id.to_bytes(1, 'big'),
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"offset": offset.to_bytes(4, 'big'),
"speed_level": speed_level.to_bytes(1, 'big'),
"frames_per_burst": frames_per_burst.to_bytes(1, 'big'),
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"snr": helpers.snr_to_bytes(snr),
}
return self.construct(FR_TYPE.BURST_ACK, payload)
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def build_arq_burst_nack(self, session_id: bytes, offset, speed_level: int,
frames_per_burst: int, snr: int):
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payload = {
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"session_id": session_id.to_bytes(1, 'big'),
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"offset": offset.to_bytes(4, 'big'),
"speed_level": speed_level.to_bytes(1, 'big'),
"frames_per_burst": frames_per_burst.to_bytes(1, 'big'),
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"snr": helpers.snr_to_bytes(snr),
}
return self.construct(FR_TYPE.BURST_NACK, payload)