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nanotime-specification.md

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Nanotime

A simple and convenient binary date & time format in 64 bits. Nanotime values are directly comparable, and the standard Gregorian fields are easily extractable.

Features

  • Encodes a complete date & time into a 64-bit unsigned integer.
  • Fields (including year) are compatible with ISO-8601.
  • Maintenance-free (no leap second tables to update).
  • Easily converts to human readable fields.
  • Supports years 1970 to 2226.
  • Supports time units to the nanosecond.
  • Supports leap years and leap seconds.
  • Values are in timezone zero by default.
  • Encoded values are comparable.

Encoding

Time fields are bit-encoded according to the following table, which lists their bit positions, bit width, and minimum and maximum allowed values.

Field Position Width Min Max Extraction Algorithm
Year 56 8 1970 2226 (value >> 56) + 1970
Month 52 4 1 12 (value >> 52) & 15
Day 47 5 1 31 (value >> 47) & 31
Hour 42 5 0 23 (value >> 42) & 31
Minute 36 6 0 59 (value >> 36) & 63
Second 30 6 0 60 (value >> 30) & 63
Microsecond 0 30 0 999999999 value & 0x3fffffff

Special Field Notes

The Year Field

The year field is interpreted as an unsigned integer with a "zero year" of 1970. For example, a year field value of 30 represents the year 2000.

The Second Field

The second field goes to 60 to support leap seconds.

Time Zone

Values must be relative to UTC, unless other outside accompanying data or agreements specify otherwise.

Invalid Encoding

If any field contains values outside of its allowed range, the time value is invalid.

Example

Encoded Value ISO8601 Equivalent Meaning
0x0fad2164076290ee 1985-10-26T08:22:16.123900142Z Oct 26th, 1985 8:22:16.123900142 UTC

Comparability

  • Adding a day (Oct 27th, 1985 8:22:16.123900142) encodes to 0x0fada164076290ee, which is greater than 0x0fad2164076290ee.
  • Subtracting a minute (Oct 26th, 1985 8:21:16.123900142) encodes to 0x0fad2154076290ee, which is less than 0x0fad2164076290ee.

License

Copyright 2018 Karl Stenerud

Specification released under Creative Commons Attribution 4.0 International Public License https://creativecommons.org/licenses/by/4.0/