v1.9.0 - allow sorting of zones by name or offset-name; reduce flash by 1100-1300 bytes on AVR

• 1.9.0 (2021-12-02, TZDB 2021e)
  • Add ZoneSorterByName and ZoneSorterByOffsetAndName classes
    to sort zone indexes, ids, or names according to 2 pre-defined sorting
    criteria: (1) by name, or (2) by UTC offset and then by name.
    • See the Zone Sorting section in the
      USER_GUIDE.md.
    • Adds a new dependency to
      AceSorting library.
  • Add examples/CompareAceTimeToHinnantDate to compare the performance of
    AceTime compared to Hinnant date library.
    • AceTime seems to be about 90X faster for converting date-time
      components to epoch seconds.
  • Add MaxBufSize comment field into zonedb[x]/zone_infos.h which is the
    maximum over all zones in that file. Must be less than or equal to
    ExtendedZoneProcessor::kMaxTransitions.
  • Potential Breaking Change: class TransitionStorage
    • Rename getHighWater() to getAllocSize(). This now returns the
      maximum number of transitions that has been allocated so far, which
      happens to be getHighWater() + 1.
    • Rename resetHighWater() to resetAllocSize().
    • Rename ExtendedZoneProcessor::resetTransitionHighWater() to
      resetTransitionAllocSize().
    • All of these methods were intended for internal debugging so these
      changes are not considered to be an API change.
    • The semantics of these methods are now closer to the algorithm in
      AceTimePython/zone_processor.ZoneProcessor.
  • Breaking Change: Extract BasicZoneProcessorCache and
    ExtendedZoneProcessorCache out of BasicZoneManager and
    ExtendedZoneManager. Remove all pure virtual methods from
    ZoneManager, making the class hierarchy non-polymorphic.
    • Saves 1100-1300 bytes of flash on AVR processors.
    • See Migrating to v1.9 for
      migration info.
  • Breaking Change: Remove pure virtual methods from LinkManager,
    analogous to their removal from ZoneManager.
    • Saves 68 bytes of flash on AVR processors.
    • See Migrating to v1.9 for
      migration info.

v1.8.2 - upgrade to TZDB 2021e

• 1.8.2 (2021-10-28, TZDB 2021e)
  • Update to TZDB 2021e.
    • https://mm.icann.org/pipermail/tz-announce/2021-October/000069.html
    • Palestine will fall back 10-29 (not 10-30) at 01:00.

v1.8.1 - upgrade to TZDB 2021d

• 1.8.1 (2021-10-18, TZDB 2021d)
  • Add make -C examples/MemoryBenchmark epoxy to GitHub actions.
  • Upgrade to TZDB 2021d.

v1.8.0 - extract Clocks to AceTimeClock; replace Wire.h with AceWire.h; extract thin links to LinkManagers

• 1.8.0 (2021-10-15, TZDB 2021c)
  • Breaking Change: Move clock classes under ace_time::clock and
    implementation classes under ace_time::hw to the new
    AceTimeClock repo.
    • Classes remain in the same C++ namespace.
    • Client code needs to add #include <AceTimeClock.h>.
    • See Migrating to v1.8 for
      migration info.
  • Breaking Change: Convert DS3231.h into a template class with an
    indirect dependency to <AceWire.h>, replacing direct dependency on
    <Wire.h>.
    • Just including the <Wire.h> header causes flash memory to be
      consumed, even if Wire object is never used.
    • Saves 1000-1500 bytes of flash on AVR, and up to 4000 bytes on STM32.
    • See Migrating to v1.8 for
      migration info.
  • Breaking Change: Extract thin link functionality from
    BasicZoneManager and ExtendedZoneManager into new BasicLinkManager
    and ExtendedLinkManager.
    • Saves 200-500 bytes of flash memory if the feature is not used.
    • Client application can determine whether to pay for this
      functionality, instead of automatically being included into the
      ZoneManager.
    • See the Thin Links section in the User
      Guide and Migrating to v1.8 for
      migration info.
  • Simplify documentation
    • Merge docs/installation.md into README.md.
    • Move docs/date_time_timezone.md to USER_GUIDE.md.
    • Remove docs/clock_system_clock.md after migrating it to
      the AceTimeClock project.
    • Merge docs/comparisons.md into README.md.

v1.7.5 - upgrade to TZDB 2021c; fix edge case bug when Transition occurs at ZoneEra transition

• 1.7.5 (2021-10-06, TZDB 2021c)
  • Bug Fix: Update ExtendedZoneProcessor.h to implement better
    detection of Transitions that occur at the exact same time as the switch
    to a different ZoneEra.
    • They are now considered to happen at the same time if any of the 'w'
      time, 's' time, or 'u' time are equal.
    • The behavior of ExtendedZoneProcessor.h should now be identical
      to zone_processor.py in the AceTimePython library.
    • Seems to affect only Europe/Lisbon in 1992, which is not a part of
      the predefined zonedb or zonedbx database, which normally include
      only 2000 until 2050.
  • Testing
    • Create AceTimePython
      library extracted from the previously split
      AceTimeTools project.
    • Update ace_time/testing/ExtendedTransitionTest.h to validate
      the exact equality between the observed maximum buffer size of
      TransitionStorage as observed by ExtendedZoneProcessor and the
      buffer size calculated by AceTimeTools using zone_processor.py of
      AceTimePython library.
    • Create examples/DebugZoneProcessor for debugging the internal logic
      of ExtendedZoneProcessor.
  • Tool Chain
    • Upgrade ESP8266 Core from 2.7.4 to 3.0.2.
      • Flash consumption increases by 3-5 kB across the boad.
    • Upgrade Arduino CLI from 0.19.1 to 0.19.2.
    • Upgrade Arduino IDE from 1.8.13 to 1.8.16.
    • Upgrade Teensyduino from 1.54 to 1.55.
    • Upgrade SparkFun SAMD Core from 1.8.3 to 1.8.4.
  • TZDB Upgrade TZDB from 2021a to 2021c.
    • TZDB 2021b is skipped because of controversial changes which were
      reverted in 2021c.
    • 2021c announcement:
      https://mm.icann.org/pipermail/tz-announce/2021-October/000067.html
    • 2021b announcement:
      https://mm.icann.org/pipermail/tz-announce/2021-September/000066.html
    • Jordan now starts DST on February's last Thursday.
    • Samoa no longer observes DST.
    • 10 Zones from 2021a were converted to Links:
      • Africa/Accra -> Africa/Abidjan
      • America/Atikokan -> America/Panama
      • America/Blanc-Sablon -> America/Puerto_Rico
      • America/Creston -> America/Phoenix
      • America/Curacao -> America/Puerto_Rico
      • America/Nassau -> America/Toronto
      • America/Port_of_Spain -> America/Puerto_Rico
      • Antarctica/DumontDUrville -> Pacific/Port_Moresby
      • Antarctica/Syowa -> Asia/Riyadh
      • Pacific/Enderbury -> Pacific/Kanton
    • 1 new Zone was created:
      • Pacific/Kanton
    • BasicZoneManager now supports 258 Zones and 193 Links using the
      zonedb database
    • ExtendedZoneManager now supports 377 Zones and 217 Links using the
      zonedbx database

v1.7.4 - move tools and validation tests into separate projects

• 1.7.4 (2021-08-26)
  • Move ./tools directory into new
    AceTimeTool repo.
  • Move ./tests/validation directory into new
    AceTimeValidation repo.
    • Update .github/workflows/validation.yml to use AceTimeValidation
      instead of ./tests/validation.
  • This is a maintenance release. No changes to the core library code.

1.7.3 - fix broken documentation links; maintenance release before major refactoring

• 1.7.3 (2021-08-25)
  • Fix numerous broken links in documents moved to docs/*.md in an earlier
    refactoring.
  • Add experimental DS3231Module class that uses AceWire library.
  • This is a maintenance release before some major refactoring. No changes to
    core library code.

v1.7.2 - add ZoneDateTime::normalize(); upgrade to AceRoutine v1.3.1; make clockMillis() non-virtual

• 1.7.2 (2021-06-02)
  • Bug Fix: Add ZonedDateTime::normalize(), which must be called by
    the client code after calling a ZonedDateTime mutation function.
    • See ZonedDateTime Normalization.
    • Increases flash usage by 222 bytes by making this single call on an
      AVR unfortunately.
  • Migrate PrintStr::getCstr() in AceCommon <=1.4.4 to the shorter
    PrintStr::cstr() in AceCommon >= 1.4.5.
  • Migrate to AceRoutine v1.3.1, which changes
    AceRoutine::coroutineMillis() into non-virtual.
  • Change SystemClock to instantiate from SystemClockTemplate, which
    allows SystemClock::clockMillis() to also become non-virtual. Saves
    20-40 bytes of flash. No discernible changes in CPU time.

v1.7.1 - simplify SystemClock getSeconds{Since,To}SyncAttempt() methods

• 1.7.1 (2021-04-02)
  • Simplify calculation of SystemClock::getSecondsSinceSyncAttempt()
    and SystemClock::getSecondsToSyncAttempt(), which substantially
    simplifies the implementation of SystemClockLoop and
    SystemClockCoroutine.
  • Update tests/auniter.ini to be consistent with my other libraries. Add
    entries for env:teensy32 (which had been supported for a while) and
    env:mkr1000 (which I just received).

v1.7 - refactor USER_GUIDE.md; get SystemClock sync status; add Stm32F1Clock

• 1.7 (2021-03-24, TZ DB version 2021a)
  • AceTime now has a
    GitHub Discussion.
    • Use that for general questions and discussions.
    • Reserve GitHub Issues
      for bugs and feature requests.
  • Add tools/compare_noda to compare Noda Time against AceTime.
    • Add --nzd_file flag to compare_noda to allow custom NodaZoneData
      files.
    • Run the Noda Time TzdbCompiler manually to generate custom
      tzdata$(TZ_VERSION).nzd for the specific TZDB version specified in
      the Makefile.
    • Add tests/validation/BasicNodaTest which matches AceTime completely
      from year 2000 until 2050.
    • Add tests/validation/ExtendedNodaTest which maches AceTime
      completely from year 1974 until 2050.
    • Identical results to BasicHinnantDateTest and
      ExtendedHinnantDateTest.
  • Add ace_time::clock::Stm32F1Clock and ace_time::hw::Stm32F1Rtc
    • Specialized classes for the STM32F1 chip, particularly the Blue Pill
      board, using the LSE_CLOCK (low speed external clock).
      • Blue Pill already includes the external 32.768 kHz
        crystal on pins C14 and C15.
    • Alternative to the ace_time::clock::StmRtcClock class, which uses
      the generic STM32RTC library, which does not fully work on the
      STM32F1.
      • STM32RTC forgets the date fields upon power reset, preserving
        only the time fields.
    • These classes write directly into the 32-bit RTC register on the F1,
      allowing AceTime to preserve both date fields and time fields.
  • Massive refactoring of USER_GUIDE.md and README.md for clarity
    • Extract subsections of USER_GUIDE.md into separate docs,
      making USER_GUIDE.md shorter and hopefully more digestable.
    • Rename most of USER_GUIDE.md into docs/date_time_timezone.md.
    • Extract Clock classes into docs/clock_system_clock.md
    • Extract Installation into docs/installation.md.
    • Extract Validation and Testing into docs/validation.md.
    • Extract Comparisons into docs/comparisons.md.
    • Add documentation for StmRtcClock and Stm32F1Clock.
  • Remove virtual destructor from ace_time::clock::Clock class.
    • Saves 618 bytes of flash on 8-bit AVR processors, 328 bytes on SAMD21,
      but only 50-60 bytes on other 32-bit processors.
  • Finish a working implementation of acetz.py.
    • Includes support for fold.
    • Create BasicAcetzTest and ExtendedAcetzTest and verify all zones
      validate.
  • Time zone short names are printed with spaces instead of underscore.
    • Various printShortNameTo() and printShortTo() methods now print
      the short names with the underscore replaced with a space. Example,
      instead of "Los_Angeles", it is now "Los Angeles".
    • It seems to be more reasonable for most time zones.
    • The time zone full name continues to print the entire canonical
      timezone identifier, e.g. "America/Los_Angeles".
    • Applications that need finer control will have to provide their own
      rendering logic.
  • SystemClock
    • Fix SystemClock::forceSync() that crashes if the referenceClock is
      null.
      • Used mostly for debugging and testing, so I doubt anyone ran into
        this.
    • Add methods to retrieve the sync status of SystemClock.
      • getSecondsSinceSyncAttempt()
      • getSecondsToSyncAttempt()
      • `getClockSlew()
      • getSyncStatusCode()
      • See System Clock
        Status
        for details.
    • Potentially Breaking: Move various internal constants in
      SystemClockLoop and SystemClockCoroutine to private.
      • Examples kStatusReady, kStatusSent, kStatusOk`k
      • These were all related to the internal finite state machine which
        should not have been exposed publically.
      • The sync status of SystemClock is now exposed through
        documented public methods described above.
  • NtpClock
    • Add warning that calling analogRead() too often (e.g. using buttons
      on a resistor ladder using AceButton library) on ESP8266 causes the
      WiFi connection to drop after 5-10 seconds.