8000 Fix float arithmetic in BLF reader by pierreluctg · Pull Request #1927 · hardbyte/python-can · GitHub
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Fix float arithmetic in BLF reader #1927

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Merged
merged 2 commits into from
Mar 6, 2025
Merged

Fix float arithmetic in BLF reader #1927

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726f3a5
Fix float arithmetic in BLF reader
pierreluctg Feb 26, 2025
55b986f
Remove the allowed_timestamp_delta from the BLF UT
pierreluctg Feb 26, 2025
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5 changes: 3 additions & 2 deletions can/io/blf.py
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
import struct
import time
import zlib
from decimal import Decimal
from typing import Any, BinaryIO, Generator, List, Optional, Tuple, Union, cast

from ..message import Message
Expand Down Expand Up @@ -264,8 +265,8 @@ def _parse_data(self, data):
continue

# Calculate absolute timestamp in seconds
factor = 1e-5 if flags == 1 else 1e-9
timestamp = timestamp * factor + start_timestamp
factor = Decimal("1e-5") if flags == 1 else Decimal("1e-9")
timestamp = float(Decimal(timestamp) * factor) + start_timestamp
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I think that can be achieved without Decimal:

            factor = 100_000 if flags == 1 else 1_000_000_000
            timestamp = (timestamp + round(start_timestamp * factor)) / factor

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I agree that we can achieve it without Decimal.
But what is the downside of using Decimal?

IMO, using the Python built-in module Decimal makes it very obvious what we are doing here.


if obj_type in (CAN_MESSAGE, CAN_MESSAGE2):
channel, flags, dlc, can_id, can_data = unpack_can_msg(data, pos)
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1 change: 0 additions & 1 deletion test/logformats_test.py
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Expand Up @@ -694,7 +694,6 @@ def _setup_instance(self):
check_fd=True,
check_comments=False,
test_append=True,
allowed_timestamp_delta=1.0e-6,
preserves_channel=False,
adds_default_channel=0,
)
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