[smoltafet]

Summary of Changes

• BLFReader and BLFWriter accept a new optional tz argument (a datetime.tzinfo), following the existing tz parameter of the ASC reader/writer.
• The BLF header stores the measurement start/stop times as a timezone-less SYSTEMTIME. It is now interpreted (reader, and writer in append mode) and written (writer) in the given timezone instead of always UTC. Message timestamps are relative to the header start time, so they shift accordingly.
• The module-level helpers systemtime_to_timestamp and timestamp_to_systemtime gained the same optional parameter; their defaults are unchanged.
• Default behavior is unchanged: without tz, everything keeps assuming UTC.

This addresses the compatibility problem from the issue: CANoe writes the header timestamps in the local time of the recording computer, so reading such a file shifted all timestamps unless you happened to be in UTC. Now you can pass e.g. tz=ZoneInfo("Europe/Berlin") (or the matching fixed offset) on both sides.

Related Issues / Pull Requests

• Closes BLFReader and BLFWriter should have a timezone optional argument #2010

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactoring
• Other (please describe):

Checklist

• I have followed the contribution guide.
• I have added or updated tests as appropriate.
• I have added or updated documentation as appropriate.
• I have added a news fragment for towncrier.
• All checks and tests pass (tox).

Additional Notes

Tests: new TestBlfTimezone in test/logformats_test.py covers the SYSTEMTIME conversion helpers, a write/read round-trip with a timezone (including that reading without tz shifts the timestamps by exactly the offset), and append mode keeping the start timestamp. Full logformats suite passes (82 passed, 10 skipped); ruff check (project pin) and black --check are clean on the changed files.

[smoltafet]

Hi @zariiii9003, could you take a look at this when you have a moment? Happy to fix up anything that needs changing. Thanks!