Re: The 8-Byte Two-Step

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From	Marko Rauhamaa <marko@pacujo.net>
Newsgroups	comp.misc
Subject	Re: The 8-Byte Two-Step
Date	Sun, 21 Sep 2014 00:48:44 +0300
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Bob Eager <news0002@eager.cx>:

>>    (mqhp->mq_maxsz + MQ_ALIGNSIZE - 1) & ~(MQ_ALIGNSIZE - 1);
>
> Standard bit of code. I can't remember when I didn't know that one!

Yes, but I suppose the knowledge is fast eroding among coders. I can't
remember having been taught it. I must have learned it from other
people's assembly and C code.

Somehow that reminds me of an ancient trick I learned from some TI-56
program. Here's a compact way to figure out how many days are between
any (ISO 8601) dates:

========================================================================
#!/usr/bin/env python

import sys

def gregorian_day_count(isodate):
    year, month, day = map(int, isodate.split('-'))
    a, b = divmod(12 * year + month + 1185, 12)
    return int(a * 365.2425) + int(30.573 * b + 0.706) + day

def main():
    print gregorian_day_count(sys.argv[2]) - gregorian_day_count(sys.argv[1])

if __name__ == '__main__':
    main()
========================================================================

Usage:

    ./datediff.py 1960-02-03 2014-09-09


Marko

Thread

The 8-Byte Two-Step Rich <rich@example.invalid> - 2014-09-20 20:41 +0000
  Re: The 8-Byte Two-Step Bob Eager <news0002@eager.cx> - 2014-09-20 21:14 +0000
    Re: The 8-Byte Two-Step Marko Rauhamaa <marko@pacujo.net> - 2014-09-21 00:48 +0300
      Re: The 8-Byte Two-Step Bob Eager <news0002@eager.cx> - 2014-09-21 08:27 +0000
        Re: The 8-Byte Two-Step Marko Rauhamaa <marko@pacujo.net> - 2014-09-21 14:14 +0300
          Re: The 8-Byte Two-Step Marko Rauhamaa <marko@pacujo.net> - 2014-09-23 11:19 +0300
          Re: The 8-Byte Two-Step Christian Neukirchen <chneukirchen@gmail.com> - 2014-09-23 18:26 +0200
      Re: The 8-Byte Two-Step mm0fmf <none@mailinator.com> - 2014-09-21 20:45 +0100
  Re: The 8-Byte Two-Step Sylvia Else <sylvia@not.at.this.address> - 2014-09-21 13:42 +1000

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