From: Ted Dennison <dennison@telepath.com>
Subject: Re: Using "delay until" in real-time
Date: Tue, 12 Dec 2000 23:49:25 GMT
Date: 2000-12-12T23:49:25+00:00 [thread overview]
Message-ID: <916di4$bl8$1@nnrp1.deja.com> (raw)
In-Reply-To: 916aqq$9a7$1@nnrp1.deja.com
In article <916aqq$9a7$1@nnrp1.deja.com>,
Mike Silva <mjsilva@my-deja.com> wrote:
> Yep. You could, e.g. add 1.0 to Start_time and zero Iteration_count
> every 60 iterations.
>
Ahhh. That's essentially what I was talking about doing.
> Still, I think it's better to try and represent your iteration in
> units of Ada.Real_Time.Tick. Then you are never dividing, only adding
> a scalar. If Ada.Real_Time.Tick can exactly represent your system
> tick of 1/240 sec. then you should never have an error. Then the
> question becomes whether Tick is an exact representation of the system
> tick time(seems like it would have to be!).
I don't know about that. The system call on this OS to set the clock
rate takes in units of iterations per second. If that is the actual
units that the real-time clock hardware uses, then there's no possible
way for something expressed in units of seconds (like
Ada.Real_Time.Tick) to represent the *exact* same amount of time.
However, its quite possible that the real-time clock hardware on my
platform (PC) uses something like nannoseconds, and the OS call just
approximates that. In that case it indeed ought to be possible for
Ada.Real_Time.Tick to be an exact match for what the hardware clock
uses. However, since this compiler works with any PC-based version of
this OS, it could be that there was no good way of knowing what the
real-time clock's exact internal representation of time would be, so
they made Ada.Real_Time.Tick an approximation anyway. I'll have to look
into this issue...
--
T.E.D.
http://www.telepath.com/~dennison/Ted/TED.html
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next prev parent reply other threads:[~2000-12-12 23:49 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-12-12 16:27 Using "delay until" in real-time Ted Dennison
2000-12-12 18:01 ` Mike Silva
2000-12-12 19:57 ` Ted Dennison
2000-12-12 23:02 ` Mike Silva
2000-12-12 23:49 ` Ted Dennison [this message]
2000-12-18 6:26 ` Ray Blaak
2000-12-12 20:00 ` Ken Garlington
2000-12-12 20:40 ` Ted Dennison
2000-12-13 4:02 ` Ken Garlington
2000-12-13 14:29 ` Ted Dennison
2000-12-13 16:53 ` Larry Hazel
2000-12-13 17:41 ` Ted Dennison
2000-12-12 20:22 ` Keith Thompson
2000-12-12 20:54 ` Ted Dennison
2000-12-13 5:35 ` tmoran
2000-12-12 20:23 ` David C. Hoos, Sr.
2000-12-12 21:58 ` Ted Dennison
2000-12-12 23:18 ` Jeff Carter
2000-12-12 21:18 ` JP Thornley
2000-12-12 22:31 ` Ted Dennison
2000-12-13 8:02 ` Brian Orpin
2000-12-13 17:32 ` JP Thornley
2000-12-12 23:09 ` Ted Dennison
2000-12-13 7:43 ` Brian Orpin
2000-12-15 0:27 ` Frank
2000-12-19 7:50 ` Martin Gangkofer
2000-12-20 3:32 ` Ted Dennison
2000-12-20 5:29 ` tmoran
2000-12-20 7:59 ` Martin Gangkofer
2000-12-20 9:15 ` java servlets JF Harrison
2000-12-20 12:50 ` Using "delay until" in real-time Marin David Condic
2000-12-21 0:08 ` Alejandro R. Mosteo
2000-12-20 3:17 ` Ted Dennison
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