Migrate bintime support into hightime (for waveforms)

[mikeprosserni]

Tech Debt

Currently, waveform.Timing is a generic timing object that can be either hightime or bintime. We should standardize on hightime so that we can change waveform.Timing to just be hightime.

To enable this, we will need to upgrade hightime (making changes in the hightime repo) to support the bintime internal representation, and to be able to construct a hightime with bintime data.

Doing this would mean that we would no longer need bintime as a public type, which means users would never have to think about which timing (hightime vs bintime) to use. Any API methods that currently accept bintime should then be changed to take hightime only.

The pickle representation of hightime could present a challenge here. One idea is to use a different pickle representation when it contains a bintime. The reduce method can return a different constructor or static method.
e.g. if has_bintime: return (datetime.from_cvi, [cvi_msb, cvi_lsb]); else: return crazy datetime binary buffer

AB#3247639

[bkeryan]

nitypes.bintime.DateTime sort of does the inverse of this, lazily caching a hightime when needed for calendar calculations: https://github.com/ni/nitypes-python/blob/main/src/nitypes/bintime/_datetime.py#L274

    def _to_hightime_datetime(self) -> ht.datetime:
        """Return self as a :any:`hightime.datetime`."""
        if self._hightime_cache is None:
            self._hightime_cache = _HT_EPOCH_1904 + self._offset._to_hightime_timedelta()
        return self._hightime_cache

    # Calculating the year/month/day requires knowledge of leap years, days per month, etc., so
    # defer to hightime.datetime.
    @property
    def year(self) -> int:
        """The year."""
        return self._to_hightime_datetime().year

    @property
    def month(self) -> int:
        """The month, between 1 and 12 inclusive."""
        return self._to_hightime_datetime().month

    @property
    def day(self) -> int:
        """The day of the month, between 1 and 31 inclusive."""
        return self._to_hightime_datetime().day

To enable NI-BTF in hightime without unnecessary conversions, it may be desirable to allow constructing the hightime.datetime with either the hightime representation or the NI-BTF representation, and then lazily convert to the other representation when needed (convert to hightime to do calendar stuff, convert to NI-BTF to send over gRPC). The nitypes.bintime benchmarks may help choose whether it's necessary for the conversion to be lazy in both directions or only in one direction.

[bkeryan]

nitypes.bintime also has NumPy-backed TimeDelta and DateTime arrays. Does it make sense to move these? hightime does not have a NumPy dependency.

[marcoskirsch]

NumPy is a very heavyweight dependency. I would rather not force it on all clients if we can avoid it.

[bkeryan]

It sounds like it makes sense to keep the NumPy stuff in nitypes and only move the support for 128-bit fixed point timestamps into hightime.