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-Add crc8 for python
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@lorenzo-gomez-windhover
lorenzo-gomez-windhover committed Nov 22, 2024
1 parent b240aac commit a102801
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Showing 2 changed files with 147 additions and 2 deletions.
8 changes: 7 additions & 1 deletion openc3/python/openc3/interfaces/protocols/crc_protocol.py
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@
from openc3.interfaces.protocols.protocol import Protocol
from openc3.accessors.binary_accessor import BinaryAccessor
from openc3.utilities.logger import Logger
from openc3.utilities.crc import Crc16, Crc32, Crc64
from openc3.utilities.crc import Crc8, Crc16, Crc32, Crc64


# Creates a CRC on write and verifies a CRC on read
Expand Down Expand Up @@ -120,6 +120,12 @@ def __init__(
if self.endianness == "BIG_ENDIAN":
endianness = ">"
match self.bit_size:
case 8:
self.pack = f"{endianness}B"
if len(args) == 0:
self.crc = Crc8()
else:
self.crc = Crc8(*args)
case 16:
self.pack = f"{endianness}H"
if len(args) == 0:
Expand Down
141 changes: 140 additions & 1 deletion openc3/python/test/interfaces/protocols/test_crc_protocol.py
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@
from openc3.interfaces.protocols.burst_protocol import BurstProtocol
from openc3.packets.packet import Packet
from openc3.streams.stream import Stream
from openc3.utilities.crc import Crc16, Crc32, Crc64
from openc3.utilities.crc import Crc16, Crc32, Crc64, Crc8


class TestCrcProtocol(unittest.TestCase):
Expand Down Expand Up @@ -347,6 +347,33 @@ def test_does_nothing_if_protocol_added_as_write(self):
self.assertEqual(len(packet.buffer), 8)
self.assertEqual(packet.buffer, TestCrcProtocol.buffer)

def test_reads_the_8_bit_crc_field_and_compares_to_the_crc(self):
self.interface.stream = TestCrcProtocol.CrcStream()
self.interface.add_protocol(BurstProtocol, [], "READ_WRITE")
self.interface.add_protocol(
CrcProtocol,
[
"CRC", # item name
"FALSE", # strip crc
"ERROR", # bad strategy
-8, # bit offset
8,
], # bit size
"READ_WRITE",
)
self.interface.target_names = ["TGT"]
packet = Packet("TGT", "PKT")
packet.append_item("DATA", 32, "UINT")
packet.append_item("CRC", 8, "UINT")

TestCrcProtocol.buffer = b"\x00\x01\x02\x03"
crc = Crc8().calc(TestCrcProtocol.buffer)
TestCrcProtocol.buffer += struct.pack(">B", crc) # [crc].pack("n")

packet = self.interface.read()
self.assertEqual(len(packet.buffer), 5)
self.assertEqual(packet.buffer, TestCrcProtocol.buffer)

def test_reads_the_16_bit_crc_field_and_compares_to_the_crc(self):
self.interface.stream = TestCrcProtocol.CrcStream()
self.interface.add_protocol(BurstProtocol, [], "READ_WRITE")
Expand Down Expand Up @@ -433,6 +460,39 @@ def test_reads_the_64_bit_crc_field_and_compares_to_the_crc(self):

# context "with a specified CRC poly, seed, xor, and reflect"

def test_reads_the_8_bit_crc_field_and_compares_to_the_crc2(self):
self.interface.stream = TestCrcProtocol.CrcStream()
self.interface.add_protocol(BurstProtocol, [], "READ_WRITE")
self.interface.add_protocol(
CrcProtocol,
[
"CRC", # item name
"FALSE", # strip crc
"ERROR", # bad strategy
-8, # bit offset
8, # bit size
"BIG_ENDIAN", # endianness
0x39, # poly for CRC-8/DARC
0x0, # seed
"TRUE", # xor
"TRUE", # reflect
],
"READ_WRITE",
)
self.interface.target_names = ["TGT"]
packet = Packet("TGT", "PKT")
packet.append_item("DATA", 32, "UINT")
packet.append_item("CRC", 8, "UINT")

TestCrcProtocol.buffer = b"\x00\x01\x02\x03"
crc8 = Crc8(0x39, 0, True, True)
crc = crc8.calc(TestCrcProtocol.buffer)
TestCrcProtocol.buffer += struct.pack(">B", crc)

packet = self.interface.read()
self.assertEqual(len(packet.buffer), 5)
self.assertEqual(packet.buffer, TestCrcProtocol.buffer)

def test_reads_the_16_bit_crc_field_and_compares_to_the_crc2(self):
self.interface.stream = TestCrcProtocol.CrcStream()
self.interface.add_protocol(BurstProtocol, [], "READ_WRITE")
Expand Down Expand Up @@ -606,6 +666,33 @@ def test_disconnects_if_the_crc_does_not_match(self):
stdout.getvalue(),
)

def test_can_strip_the_8_bit_crc_at_the_end(self):
self.interface.stream = TestCrcProtocol.CrcStream()
self.interface.add_protocol(BurstProtocol, [], "READ_WRITE")
self.interface.add_protocol(
CrcProtocol,
[
"CRC", # item name
"TRUE", # strip crc
"ERROR", # bad strategy
-8, # bit offset
8,
], # bit size
"READ_WRITE",
)
self.interface.target_names = ["TGT"]
packet = Packet("TGT", "PKT")
packet.append_item("DATA", 32, "UINT")
packet.append_item("CRC", 8, "UINT")

TestCrcProtocol.buffer = b"\x00\x01\x02\x03"
crc = Crc8().calc(TestCrcProtocol.buffer)
TestCrcProtocol.buffer += struct.pack(">B", crc)

packet = self.interface.read()
self.assertEqual(len(packet.buffer), 4)
self.assertEqual(packet.buffer, TestCrcProtocol.buffer[0:4])

def test_can_strip_the_16_bit_crc_at_the_end(self):
self.interface.stream = TestCrcProtocol.CrcStream()
self.interface.add_protocol(BurstProtocol, [], "READ_WRITE")
Expand Down Expand Up @@ -768,6 +855,32 @@ def test_complains_if_the_item_does_not_exist(self):
):
self.interface.write(packet)

def test_calculates_and_writes_the_8_bit_crc_item(self):
self.interface.stream = TestCrcProtocol.CrcStream()
self.interface.add_protocol(BurstProtocol, [], "READ_WRITE")
self.interface.add_protocol(
CrcProtocol,
[
"CRC", # item name
"FALSE", # strip crc
"ERROR", # bad strategy
-40, # bit offset
8,
], # bit size
"READ_WRITE",
)
self.interface.target_names = ["TGT"]
packet = Packet("TGT", "PKT")
packet.append_item("DATA", 32, "UINT")
packet.append_item("CRC", 8, "UINT")
packet.append_item("TRAILER", 32, "UINT")
packet.buffer = b"\x00\x01\x02\x03\x3F\x04\x05\x06\x07"
self.interface.write(packet)
buffer = b"\x00\x01\x02\x03"
buffer += struct.pack(">B", Crc8().calc(b"\x00\x01\x02\x03"))
buffer += b"\x04\x05\x06\x07"
self.assertEqual(TestCrcProtocol.buffer, buffer)

def test_calculates_and_writes_the_16_bit_crc_item(self):
self.interface.stream = TestCrcProtocol.CrcStream()
self.interface.add_protocol(BurstProtocol, [], "READ_WRITE")
Expand Down Expand Up @@ -852,6 +965,32 @@ def test_calculates_and_writes_the_64_bit_crc_item(self):
buffer += b"\x04\x05\x06\x07"
self.assertEqual(TestCrcProtocol.buffer, buffer)

def test_appends_the_8_bit_crc_to_the_end(self):
self.interface.stream = TestCrcProtocol.CrcStream()
self.interface.add_protocol(BurstProtocol, [], "READ_WRITE")
self.interface.add_protocol(
CrcProtocol,
[
None, # item name None means append
"FALSE", # strip crc
"ERROR", # bad strategy
-8, # bit offset
8,
], # bit size
"READ_WRITE",
)
self.interface.target_names = ["TGT"]
packet = Packet("TGT", "PKT")
packet.append_item("DATA", 32, "UINT")
packet.append_item("CRC", 32, "UINT")
packet.append_item("TRAILER", 32, "UINT")
packet.buffer = b"\x00\x01\x02\x03\x00\x00\x00\x00\x04\x05\x06\x07"
buffer = packet.buffer
buffer += struct.pack(">B", Crc8().calc(packet.buffer))
self.interface.write(packet)
self.assertEqual(len(TestCrcProtocol.buffer), 13)
self.assertEqual(TestCrcProtocol.buffer, buffer)

def test_appends_the_16_bit_crc_to_the_end(self):
self.interface.stream = TestCrcProtocol.CrcStream()
self.interface.add_protocol(BurstProtocol, [], "READ_WRITE")
Expand Down

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