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From: stt@houdini.camb.inmet.com (Tucker Taft)
Subject: Re: Simple Real_Time.Time_Span question
Date: 1998/10/13
Message-ID: <F0s4vI.DnC.0.-s@inmet.camb.inmet.com>#1/1
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Organization: Intermetrics, Inc.
Newsgroups: comp.lang.ada
Date: 1998-10-13T00:00:00+00:00
List-Id: <comp.lang.ada>

dennison@telepath.com wrote:

: I need to convert values of Ada.Real_Time.Time_Span into floating point
: values for use in time-based simulation calculations. I'd think there *has*
: to be a way to do this, but I don't see one. All I see is the ability to do
: it indirectly via a conversion to Duration. But that looses the extra
: accuracy of Time_Span, which was the whole point of using it in the first
: place.

: Am I missing something?

You might try using Split(Time_Of(),...), and then multiplying the 
resulting reduced Time_Span by 1000 before converting it to Duration.  
That should end up preserving more of the accuracy.
You could run the 1000*<reduced Time_Span> back through the
Split(Time_Of()) combo again to get even more accuracy.
E.g.:

    function To_Float(TS : Time_Span) return Float is
        SC1, SC2, SC3 : Seconds_Count;
	TS1, TS2, TS3 : Time_Span;
    begin
	-- Use Split(Time_Of()) to split time span into seconds and fraction
	-- Repeat twice to get microseconds and fraction thereof
	Split(Time_Of(0, TS), SC1, TS1);
	Split(Time_Of(0, TS1*1000), SC2, TS2);
	Split(Time_Of(0, TS2*1000), SC3, TS3);
	    -- NOTE: it is safe to multiply by 1000 because RM95 D.8(31) 
	    -- guarantees that Time_Span'Last is >= 3600 seconds.

	-- Finally do the conversion of the remaining time-span to duration
	-- and add to other pieces.
	return (Float(SC1)*1.0E9 + Float(SC2)*1.0E6 + Float(SC3)*1.0E3
	  + Float(To_Duration(TS3*1000))) / 1.0E9;
    end To_Float;

No comment on how fast the above will run...

: --
: T.E.D.

--
-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
Intermetrics, Inc.  Burlington, MA  USA
An AverStar Company