Subj : Re: 'Leap Second' to Be Added on New Year's Eve This Year
To   : All
From : Ww84wa@aim.com
Date : Sun Jan 01 2017 09:31 pm

From: Wally W. <ww84wa@aim.com>
Subject: Re: 'Leap Second' to Be Added on New Year's Eve This Year
 
On Sun, 01 Jan 2017 19:44:48 -0500, Wally W. wrote:
 
>On Sun, 1 Jan 2017 16:12:27 -0600, Mark Lloyd wrote:
>
>>On 01/01/2017 12:46 PM, Wally W. wrote:
>>
>>[snip]
>>
>>> As I understand it, NT time uses a signed integer and tops out at
>>> 0x7FFFFFFFFFFFFFFF = in the year 30828
>>>
>>> Unhappily, no sources suggest using negative integers will allow
>>> setting the timestamp before the year 1600.
>>
>>What is the resolution of this clock? You get hundreds of billions of 
>>years if you count seconds since 1970.
>
>For Windows NT, GetSystemTimeAsFileTime is in 100s of nanonsconds
>(tenths of microseconds) since 1/1/1600.
>
>Doing the math:
>
>0x7FFFFFFFFFFFFFFF = 9223372036854775807
>
>So:
>
>9223372036854775807 / 365.25 / 86400 / (1e7)
> =  29,227
>
>29,227 + 1600 =  30,827
>
>That is close to 30,828.
>
>My approximation for leap years is too crude for a span of 30,000+
>years.
>
>Unix tops out much later in the table at the link above.
 
Above??!
 
I meant this one:
https://en.wikipedia.org/wiki/System_time
 
I forgot to paste it before.
 
 
>If I want to use the same (really durable) hardware to retrieve my
>backups in the year 292,000,000 AD, I should start using Linux now.
>
>Actually, I would have liked to have started using Linux exclusively
>years ago. 
>
>
>>1600 is a leap year, like 2000 and 2400. Maybe it has something to do 
>>with that.
>>
>>> Otherwise, timestamps could be set for any date in known history; as
>>> in 4004 BC, which by some counts includes Day One.
>>
>>The PHP I use has a strange "hole", where you can't set (with mktime) a 
>>year in the range of 0-100*. IIRC earlier years can be set, but it's one 
>>off (it thinks there is a year 0). 4004 BC** would be specified as -4003.
>>
>>* - I think this is a "convenience" that made sense with a 32-bit time_t 
>>where it adds 2000 to 0-79 and 1900 to 80-100, both 0 and 100 become 2000.
>>
>>** - I try to use CE / BCE instead of AD / BC. The numbers are the same, 
>>and it avoids a particular assumption.
>>
>>[snip]
 

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