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.

v1.6 - implement Thin Links, a lighter weight version of Fat Links; fully templatize ZoneProcessors

• 1.6
  • Remove TimeZone::kTypeBasicManaged and TimeZone::kTypeExtendedManaged
    and merge them into just regular TimeZone::kTypeBasic and
    TimeZone::kTypeExtended.
    • Significantly simplifies the implementation of TimeZone.
    • TimeZone no longer holds a reference to a ZoneProcessorCache, it
      holds only a reference to ZoneProcessor.
    • The binding of TimeZone to its BasicZoneProcessor or
      ExtendedZoneProcessor now happens early, inside the
      BasicZoneManager or the ExtendedZoneManager, instead of delaying
      it to various methods inside the TimeZone through the
      ZoneProcessorCache.
    • This change should be invisible to library clients.
  • Large internal refactoring of ZoneProcessor, no external change
    • Fully templatize BasicZoneProcessor into
      BasicZoneProcessorTemplate, and ExtendedZoneProcessor to
      ExtendedZoneProcessorTemplate.
    • Remove sentinel static ZoneEra anchor record which prevented
      easy templatization.
    • Remove direct dependency to const ZoneInfo*, replacing it with
      generic uintptr_t zoneKey.
    • Insert BrokerFactory indirection layer to provide mapping from a
      generic uintptr_t zoneKey to the corresponding ZoneInfoBroker.
    • Templatized classes now depend only on their respective
      Zone*Broker classes.
    • This change should be invisible to library clients.
  • Fix stale ZoneProcessor binding to TimeZone.
    • A dereferenced nullptr could crash the program if
      TimeZone::toTimeZoneData() was called immediately after calling the TimeZone::forZoneInfo()` factory method.
    • Some accessor methods in TimeZone (getZoneId(), printTo(),
      printShortTo()) could return incorrect values if the number of
      unique TimeZones used by an application is greater than the cache
      SIZE template parameter given to the ZoneManager.
      • The problem occurs because the ZoneProcessorCache will rebind
        a previously allocated ZoneProcessor to another TimeZone when
        it runs out of available processors in the cache.
  • Unlikely Breaking Change: Move ZoneRegistrar.h into internal/.
    • Rename BasicZoneRegistrar to basic::ZoneRegistrar.
    • Rename ExtendedZoneRegistrar to extended::ZoneRegistrar.
    • The class is an implementation detail which is used only by
      BasicZoneManager and ExtendedZoneManager. It was not exposed to
      the end user and should not cause any breaking changes.
  • Add support for Thin Links using optional linkRegistry[] parameter in
    the constructors of BasicZoneManager and ExtendedZoneManager.
    • The zonedb/zone_registry.h and zonedbx/zone_registry.h files
      now contain a kLinkRegistrySize and a LinkEntry kLinkRegistry[]
      array. Each record in the array contains a mapping of linkId to its
      zoneId.
    • The ZoneManager::createForZoneId() method will search the Thin Link
      registry if a zoneId is not found in the Zone registry.
    • See Zones and Links section in the
      USER_GUIDE.md.
  • Breaking Change: Rename ZoneManager::registrySize() to
    zoneRegistrySize().
    • Add ZoneManager::linkRegistrySize() method.
    • A ZoneManager can now hold 2 different registries: the Zone (and Fat
      Link) registry, and the Thin Link registry. So we need to
      distinguish between the 2 registries.
    • See the Default Registries section
      in the USER_GUIDE.md for an explanation of the Zone
      and Link registries.

v1.5 - officially support STM32; upgrade to TZ DB 2021a; implement fat Links

• 1.5
  • Use binary search for both ZoneManager::createForZoneName() and
    ZoneManager::createForZoneId().
    • Previously, the zone_registry.cpp was sorted by zoneName, so only
      the createForZoneName() could use the binary search. The new
      solution sorts the zone_registry.cpp entries by zoneId instead of
      zoneName. The createForZoneId() can use the binary search
      algorith.
    • The createForZoneName() can also use the binary search because
      the zoneName is converted dynamically to its zoneId using the same
      djb2 hash algorithm used by the tzcompiler.py. If there is a match,
      a final verification against the exact zoneName is performed to make
      sure that there was no hash collision.
    • Updated AutoBenchmark.ino to determine that a binary search on the
      266 zones in zonedb/zone_registry.cpp is 9-10X faster (on average)
      than a linear search through the same list. (Linear search takes ~190
      iterations; binary search takes ~9 iterations.)
  • Upgrade Link entries to be "fat links".
    • Links become essentially identical to Zone entries, with references to
      the same underlying ZoneEra records.
    • Add kZoneAndLinkRegistry[] array in zone_registry.h that contains
      all Links as well as Zones.
    • Add "Zones and Links" section in USER_GUIDE.md.
  • Implement zoneName compression using ace_common::KString.
    • Saves about 1500-2300 bytes for basic zonedb info files, and
      2500-3400 bytes for extended zonedbx info files.
  • Potentially Breaking Change: Remove transitionBufSize from
    ZoneInfo struct, and migrate to kZoneBufSize{xxx} constants in the
    zone_infos.h files.
    • This was used only in validation tests under tests/validation and
      only for Extended{xxx} tests. Saves 1 byte per Zone on 8-bit
      processors, but none on 32-bit processors due to 4-byte alignment.
    • This should have no impact on client code since this field was used
      only for validation testing.
  • API Breaking Change: Replace BasicZone::name() and shortName()
    with printNameTo() and printShortNameTo(). Same with
    ExtendedZone::name() and shortName(), replaced with printNameTo()
    and printShortNameTo().
    • After implementing zoneName compression, it was no longer possible to
      return a simple pointer to the name and shortName without using
      static memory buffers.
    • I expect almost no one to be using the BasicZone and ExtendedZone
      classes, since they are mostly useful for internal algorithms.
    • Client code that needs the old functionality can use
      BasicZone::printNameTo(Print&),
      BasicZone::printShortNameTo(Print&) (similarly for ExtendedZone)
      to print to a ace_common::PrintStr<> object, then extract the
      c-string using PrintStr::getCstr().
  • Update UnixHostDuino 0.4 to EpoxyDuino 0.5.
  • Explicitly blacklist megaAVR boards, and SAMD21 boards using
    arduino:samd Core >= 1.8.10.
    • This allows a helpful message to be shown to the user, instead of the
      pages and pages of compiler errors.
  • Update TZ Database to 2021a.
    • https://mm.icann.org/pipermail/tz-announce/2021-January/000065.html
    • "South Sudan changes from +03 to +02 on 2021-02-01 at 00:00."
  • Officially support STM32 and STM32duino after testing on STM32 Blue Pill.

v1.4.1 - actually upgrade zonedb and zonedbx files to 2020f

• 1.4.1 (2020-12-30, TZDB version 2020f for real)
  • Actually update src/ace_time/zonedb and src/ace_time/zonedbx
    zone info files to 2020f. Oops.

v1.4 - upgrade to tzdata 2020f; prelim support for STM32; huge refactoring of tools

• 1.4 (2020-12-30, TZ DB version 2020f)
  • Add entry for ManualZoneManager in
    examples/MemoryBenchmark. It seems to need
    between 0'ish to 250 bytes of flash.
  • Add support for creating and handling a TimePeriod error object.
    • Add kMaxPeriodSeconds and kInvalidPeriodSeconds constants.
    • Add forError() factory method.
    • Add error checking to toSeconds() and TimePeriod(seconds)
      constructor.
    • Printing an error object prints <Invalid TimePeriod>.
  • Add support for the STM32RTC clock on an STM32 through the
    ace_time::clock::StmRtcClock class.
    • Currently experimental and untested.
    • I do not have any STM32 boards right now, so I cannot test this code.
    • See #39 for details.
    • Thanks to Anatoli Arkhipenko (arkhipenko@).
  • Add convenience factory methods for creating manual TimeZone objects.
    Saves a lot of typing by avoiding the TimeOffset objects:
    • TimeZone::forHours()
    • TimeZone::forMinutes()
    • TimeZone::forHourMinute()
  • Fix incorrect kTypeXxx constants in ZoneManager.h. Fortunately, the
    numerical values overlapped perfectly, so didn't cause any bugs in actual
    code.
  • USER_GUIDE.md
    • Add documentation about accessing the meta information about the
      zonedb and zonedbx databases:
      • zonedb::kTzDatabaseVersion
      • zonedb::kZoneContext.startYear
      • zonedb::kZoneContext.untilYear
      • zonedbx::kTzDatabaseVersion
      • zonedbx::kZoneContext.startYear
      • zonedbx::kZoneContext.untilYear
    • Add documentation that the ZonedDateTime must always be within
      startYear and untilYear. An error object will be returned outside
      of that range.
  • Update TZ Database from 2020d to version 2020f
    • 2020e
      • https://mm.icann.org/pipermail/tz-announce/2020-December/000063.html
      • "Volgograd switches to Moscow time on 2020-12-27 at 02:00."
    • 2020f
      • https://mm.icann.org/pipermail/tz-announce/2020-December/000064.html
      • "'make rearguard_tarballs' no longer generates a bad rearguard.zi,
        fixing a 2020e bug. (Problem reported by Deborah Goldsmith.)"
    • AceTime skips 2020e
  • Update examples/AutoBenchmark to allow auto-generation of ASCII tables,
    which allows auto-generation of the README.md file. Update CPU
    benchmarks for v1.4 from v0.8, since it is much easier to update these
    numbers now. No significant performance change from v0.8.
  • Huge amounts of Python tools refactoring
    • Convert all remaining % string formatting to f-strings.
    • Convert all internal camelCase dictionary keys to snake_case for
      consistency.
    • Finish adding typing info to pass strict mypy checking.
    • Centralize most typing info into data_types/at_types.py.
    • Move various global constants into data_types/at_types.py.
    • Migrate most Arduino specific transformations into artransformer.py.
    • Move offsetCode, deltaCode, atTimeCode, untilTimeCode, rulesDeltaCode
      calculations and various bit-packing rules (e.g. at_time_modifier,
      ntil_time_modifier) into artransformer.py instead of the
      argenerator.py.
    • Include general and platform specific transformations in
      the JSON (zonedb.json or zonedbx.json) files.
    • Make argenerator.py use only the JSON output instead of making
      its own transformations.
    • Produce both LettersMap and LettersPerPolicy in the JSON file.
    • Unify CommentsCollection into CommentsMap using an Iterable
      in Dict[str, Iterable[str]].
    • Unify all transformer results into TransformerResult.
    • Check hash collisions for Link names, in addition to Zone names.
    • Rename test data generator executables to generate_data.* or some
      variations of it, to avoid confusion with unit tests which are often
      named test_xxx.py.
    • Add --input_dir flag to generate_data.cpp to allow the TZ database
      directory to be specified.
    • Add --ignore_buf_size_too_big to workaround a mismatch between
      the estimated Transition buffer size calculated by bufestimator.py
      and the actual buffer size required by ExtendedZoneProcessor.cpp.
    • Add --skip_checkout flag to tzcompiler.py to allow local
      modifications of the TZ database files to be used for code generation.
    • Add --delta_granularity flag to transformer.py to decouple it
      from --offset_granularity, so that the SAVE and RULES
      granularity can be controlled independently from the STDOFF
      granularity. The --until_at_granularity continues to control AT
      and UNTIL.
    • Make output of zinfo.py --debug to be more readable.
    • Remove --generate_zone_strings from tzcompiler.py which removes
      the ability to create zone_strings.{h,cpp}. The storage and
      optimization of strings are implementation details which seem to be
      better handled later in the pipeline.
    • Increase the range of zonedbpy database from the default
      [2000,2050) to [1974, 2050) to allow zinfo.py to handle a larger
      range of queries.
    • Merge --action and --language flags for tzcompiler.py; only
      --language flag needed right now.
    • Rename RulesMap to PoliciesMap, rules_map to policies_map,
      rule_name to policy_name etc. For consistency with ZonesMap,
      zones_map, and zone_name.
    • Add ZoneId hashes to JSON output files.

v1.3 - better ZoneId support using ZoneManager interface

• 1.3 (2020-11-30, TZ DB version 2020d)
  • Minor tweaks to silence clang++ warnings.
  • Create new ZoneManager interface (pure virtual) which is now the
    non-templatized parent to both BasicZoneManager and
    ExtendedZoneManager. Allows ZoneManager to be passed around
    poloymorphically as a pointer or reference.
  • Fix broken ZoneManager::indexForZoneName() and
    ZoneManager::indexForZoneId() caused by incorrect implementations in
    BasicZoneRegistrar and ExtendedZoneRegistrar.
  • Generate compile-time zoneIds for all zones in the form of
    zonedb::kZoneId{Zone_Name} and zonedbx::kZoneId{Zone_Name} (e.g.
    zonedb::kZoneIdAmerica_Los_Angeles). Can be given directly to
    ZoneManager::createForZoneId().
  • Add constructors to TimeZoneData to allow initializers to set
    union members. Useful for initializing arrays of TimeZoneData.
  • Add ManualZoneManager implementation of ZoneManager which implements
    only createForTimeZoneData(). Useful in applications which support only
    TimeZone::kTypeManual (fixed std and dst offsets) due to memory
    constaints.
  • Add documentation of TimeZoneData, TimeZone::toTimeZoneData(), and
    ZoneManager::createFromTimeZoneData() to USER_GUIDE.md. Looks like I
    added the class in v0.5 but forgot to document it.
  • Implement LocalDateTime::compareTo() using only its components instead
    of internally converting to epochSeconds. Not all LocalDateTime can be
    represented by an epochSeconds, so this change makes the algorithm more
    robust. The semantics of the method should remain unchanged.
  • Update the doxygen docs of the compareTo() methods of LocalDateTime,
    LocalTime, LocalDate, OffsetDateTime and ZonedDateTime to clarify
    the semantics of those operations.

v1.2.1 - add Table of Contents to USER_GUIDE.md

• 1.2.1 (2020-11-12, TZ DB version 2020d)
  • No functional change in this release. Mostly documentation.
  • Update examples/MemoryBenchmark numbers from v0.8 to v1.2 with
    new auto-generator scripts.
  • Add Table of Contents to USER_GUIDE.md to help navigate the long
    document.

v1.2 - migrate low-level common code to AceCommon library

• 1.2 (2020-10-31, TZ DB version 2020d)
  • Potentially Breaking: AceTime library now depends on the AceCommon
    library (https://github.com/bxparks/AceCommon) to avoid having to maintain
    multiple copies of various utility functions and classes. The API for most
    (if not all) public classes have not changed. A number of internal helper
    classes have moved to the AceCommon library. If you happen to directly use
    some of these, you need to use the AceCommon library instead.
    • Add dependency to AceCommon to all Makefiles.
    • Add a depends attribute to library.properties.
  • Replace various utlity functions and class with those from AceCommon:
    • class TimingStats
    • incrementMod(), incrementModOffset(), printPad2To(),
      printPad3To()
    • strcmp_PP()
    • strchr_P(), strrchr_P() for ESP8266 and ESP32
    • PrintStr
  • Move common/CrcEeprom.h to AceUtils
    (https://github.com/bxparks/AceUtils) library.