Groups > comp.sys.acorn.programmer > #5993

Re: Subtracting times

Subject	Re: Subtracting times
Newsgroups	comp.sys.acorn.programmer
From	Alan Adams <alan@adamshome.org.uk>
Date	2020-02-21 15:17 +0000
Message-ID	<12ecd44558.Alan.Adams@ArmX6.adamshome.org.uk> (permalink)
References	<37f8364458.Alan.Adams@ArmX6.adamshome.org.uk> <0a59594458.jmb@jmc.bruck.orange.fr> <80ec8ad6-58f7-4862-8ccd-34d8d5627c3c@googlegroups.com>
Organization	Orpheus Internet Services

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In message <80ec8ad6-58f7-4862-8ccd-34d8d5627c3c@googlegroups.com>
          Steve Drain <steve@kappa.me.uk> wrote:

> Michel  wrote:
>> Alan Adams wrote:
>>> I need a BASIC routine to subtract one 5-byte time from another and return
>>> a correctly signed result.
>> from Steve Drain (ROOL Forum 18/12/2016)
>> 
>> I wrote a library to support some of this this, as have others. It is a
>> candidate for Basalt, someday. ;-)
>> 
>> Look at http://kappa.me.uk/Libraries/lbLongs032.zip

> I suspect that this problem has been satisfactorily solved in plain BASIC,
> but that library I wrote a good while ago uses fragments of assembly to do
> the heavy lifting, because of the carry etc.

> For interest's sake I put together a couple of routines to deal solely
> with 5-byte times using assembly at:

>  http://www.kappa.me.uk/Miscellaneous/swTimeDiff.zip

> I am not sure that I have got it right, so please pull it apart. ;-)

I ran 10 sets of test data. I think it gets it wrong for the last 4. In 
each case the sign is wrong for the returned integer. The values are too 
small as well. These are the cases where the result is too large for an 
integer to hold.

The 5-byte integer values looks correct, but cannot be returned to BASIC.

I compared it with my BASIC routine. The adjustment I made after the last 
subtraction was wrong. Omitting it returned the correct answer.

A$ is the bytes (high to low) in a%, similarly for B$ and C$.
the dates are the conversion iof A% and B% to dates.

14:51:20.29 ** Clear **
A$="00 00 00 00 20 " B$="00 7F FF FF C0 " C$="FF 80 00 00 60 " 
!C%=-2147483552
A$="00:00:00 01-Jan-1900" B$="13:13:55 06-Sep-1900" !C%=-2147483552

A$="00 7F FF FF C0 " B$="00 00 00 00 20 " C$="00 7F FF FF A0 " 
!C%=2147483552
A$="13:13:55 06-Sep-1900" B$="00:00:00 01-Jan-1900" !C%=2147483552

A$="00 80 00 00 20 " B$="00 7F FF FF C0 " C$="00 00 00 00 60 " !C%=96
A$="13:13:56 06-Sep-1900" B$="13:13:55 06-Sep-1900" !C%=96

A$="00 7F FF FF C0 " B$="00 80 00 00 20 " C$="FF FF FF FF A0 " !C%=-96
A$="13:13:55 06-Sep-1900" B$="13:13:56 06-Sep-1900" !C%=-96

A$="00 FF FF FF 20 " B$="01 00 00 00 C0 " C$="FF FF FF FE 60 " !C%=-416
A$="02:27:50 13-May-1901" B$="02:27:54 13-May-1901" !C%=-416

A$="01 00 00 00 C0 " B$="00 FF FF FF 20 " C$="00 00 00 01 A0 " !C%=416
A$="02:27:54 13-May-1901" B$="02:27:50 13-May-1901" !C%=416

A$="01 FF FF FF 20 " B$="00 00 00 00 C0 " C$="01 FF FF FE 60 " !C%=-416
A$="04:55:43 22-Sep-1902" B$="00:00:01 01-Jan-1900" !C%=-416

A$="00 00 00 00 C0 " B$="01 FF FF FF 20 " C$="FE 00 00 01 A0 " !C%=416
A$="00:00:01 01-Jan-1900" B$="04:55:43 22-Sep-1902" !C%=416

A$="FF FF FF FF 20 " B$="00 00 00 00 C0 " C$="FF FF FF FE 60 " !C%=-416
A$="06:57:55 03-Jun-2248" B$="00:00:01 01-Jan-1900" !C%=-416

A$="00 00 00 00 C0 " B$="FF FF FF FF 20 " C$="00 00 00 01 A0 " !C%=416
A$="00:00:01 01-Jan-1900" B$="06:57:55 03-Jun-2248" !C%=416



-- 
Alan Adams, from Northamptonshire
alan@adamshome.org.uk
http://www.nckc.org.uk/

Thread

Subtracting times Alan Adams <alan@adamshome.org.uk> - 2020-02-18 11:55 +0000
  Re: Subtracting times Jean-Michel <jmc.bruck@orange.fr> - 2020-02-18 19:11 +0100
    Re: Subtracting times Steve Drain <steve@kappa.me.uk> - 2020-02-21 03:28 -0800
      Re: Subtracting times Alan Adams <alan@adamshome.org.uk> - 2020-02-21 12:45 +0000
      Re: Subtracting times Alan Adams <alan@adamshome.org.uk> - 2020-02-21 15:17 +0000
        Re: Subtracting times Steve Drain <steve@kappa.me.uk> - 2020-02-22 10:37 +0000
          Re: Subtracting times Steve Drain <steve@kappa.me.uk> - 2020-02-25 16:05 +0000
            Re: Subtracting times Alan Adams <alan@adamshome.org.uk> - 2020-02-25 16:35 +0000
              Re: Subtracting times Steve Drain <steve@kappa.me.uk> - 2020-02-27 17:10 +0000
                Re: Subtracting times Steve Drain <steve@kappa.me.uk> - 2020-02-27 10:06 -0800
                Re: Subtracting times Alan Adams <alan@adamshome.org.uk> - 2020-02-28 11:21 +0000
                Re: Subtracting times jeffrey.a.doggett@gmail.com - 2020-04-22 12:00 -0700
                Re: Subtracting times Martin <News03@avisoft.f9.co.uk> - 2020-04-23 00:07 +0100
                Re: Subtracting times jeffrey.a.doggett@gmail.com - 2020-04-23 03:13 -0700
                Re: Subtracting times Martin <News03@avisoft.f9.co.uk> - 2020-04-23 18:01 +0100
                Re: Subtracting times "John Williams (News)" <UCEbin@tiscali.co.uk> - 2020-04-23 18:06 +0100
                Re: Subtracting times jeffrey.a.doggett@gmail.com - 2020-04-23 11:18 -0700
                Re: Subtracting times Martin <News03@avisoft.f9.co.uk> - 2020-04-23 21:23 +0100
                Re: Subtracting times David Higton <dave@davehigton.me.uk> - 2020-04-24 15:24 +0100
                Re: Subtracting times David Higton <dave@davehigton.me.uk> - 2020-04-23 20:57 +0100
        Re: Subtracting times jgh@mdfs.net - 2020-02-23 17:39 -0800
          Re: Subtracting times Steve Drain <steve@kappa.me.uk> - 2020-02-24 10:23 +0000
            Re: Subtracting times Alan Adams <alan@adamshome.org.uk> - 2020-02-24 11:12 +0000
              Re: Subtracting times Martin <News03@avisoft.f9.co.uk> - 2020-02-24 13:05 +0000
  Re: Subtracting times Matthew Phillips <spam2011m@yahoo.co.uk> - 2020-02-19 08:35 +0000
    Re: Subtracting times Alan Adams <alan@adamshome.org.uk> - 2020-02-19 10:03 +0000
      Re: Subtracting times Sebastian Barthel <naitsabes@freenet.de> - 2020-02-19 13:04 +0000
        Re: Subtracting times Alan Adams <alan@adamshome.org.uk> - 2020-02-19 16:41 +0000
          Re: Subtracting times jgh@mdfs.net - 2020-02-19 12:01 -0800
      Re: Subtracting times Matthew Phillips <spam2011m@yahoo.co.uk> - 2020-02-23 20:46 +0000
  Re: Subtracting times Martin <News03@avisoft.f9.co.uk> - 2020-02-19 23:54 +0000
    Re: Subtracting times Alan Adams <alan@adamshome.org.uk> - 2020-02-20 11:18 +0000

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