Originally shared by David Berneda

-
Originally shared by David Berneda

A slightly optimized TDateTime functions (YearOf, MonthOf, DayOf)

https://github.com/davidberneda/FastDateTime

Aprox 41%, 23%, 24% faster, respectively

Comments

  1. David HeffernanJuly 3, 2016 at 9:35 AM

    The DivMod should be faster. Should really be a single division. The CPU instruction will give you both div and mod from a single instruction. No point doing the divide twice.

    http://stackoverflow.com/questions/20270596/how-do-i-implement-an-efficient-32-bit-divmod-in-64-bit-code

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  2. David BernedaJuly 3, 2016 at 9:45 AM

    David Heffernan Thank you David ! I just grabbed the DivMod purepascal version from DateUtils. Using System.Math DivMod is now faster in both 32 and 64 bit

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  3. David BernedaJuly 3, 2016 at 10:01 AM

    However, after profiling it shows the bottleneck (40% of time) is at the "while True" loop that guesses the month number from the day-of-the-year number.

    I've tried replacing the loop with 12 big nested "if" blocks (one per month, without using the MonthDays arrays) but the improvement is minuscule (and the code is ugly)

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  4. Jeroen Wiert PluimersJuly 3, 2016 at 10:44 AM

    Integer math (:

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  5. Johan BontesJuly 3, 2016 at 7:32 PM

    David Berneda
    use a lookup table

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  6. Tommi PramiJuly 3, 2016 at 11:05 PM

    /sub

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  7. David BernedaJuly 4, 2016 at 12:13 AM

    Johan Bontes yes, that's the definitive solution (two const arrays of byte, 365 and 366 elements)

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  8. David BernedaJuly 4, 2016 at 12:15 AM

    Johan Bontes and two more arrays, to obtain the day in the month

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  9. Jeroen Wiert PluimersJuly 4, 2016 at 5:39 AM

    David Berneda Cool! Is that optimisation on GitHub yet?

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  10. Jeroen Wiert PluimersJuly 4, 2016 at 6:56 AM

    Javier Hernández which would be very incompatible with people having a Delphi-only license of either the IDE or the 3rd party library involved. No more MidasLib.dcu headaches please...

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  11. David BernedaJuly 4, 2016 at 7:55 AM

    Jeroen Wiert Pluimers hehe no, and I'm on vacation til next monday. I can try with my mobile phone editing on github directly, but no compiler to test :-)

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  12. Jeroen Wiert PluimersJuly 4, 2016 at 12:45 PM

    David Berneda enjoy your holiday.

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  13. Balázs SzakályJuly 5, 2016 at 1:03 AM

    /sub

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  14. David BernedaJuly 11, 2016 at 4:10 AM

    Updated code, added lookup-table optimizations, Lazarus / FPC support and test project:

    https://github.com/davidberneda/FastDateTime

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  15. David BernedaJuly 11, 2016 at 9:17 AM

    Javier Hernández In the past I used AQTime but now I'm using NexusDB Quality suite (http://www.nexusdb.com/support/index.php?q=qualitysuite) and Eric Grange SamplingProfiler (https://www.delphitools.info/samplingprofiler/).

    But in this FastDateTime code the test project uses TStopWatch (GetTickCount in FPC) to compare speed

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