Re: Real Time IO routines

On Fri, 26 Oct 2007 13:00:13 -0700, andrew wrote:

On Oct 26, 1:36 pm, Ludovic Brenta <ludo...@xxxxxxxxxxxxxxxxxx> wrote:
andrew writes:
Time_Unit is defined as a constant := 10#1.0#E-9, is Time_Unit then
a "real literal"? How can I convert a "real literal" to a scalar
type (maybe that's a contradiction?)?

Real literals are of the type universal_real which (a) is scalar and
(b) converts implicitly to any other floating-point type. Does that
answer your question?

To Ludovic: Ahh, so if I had to define a universal_real I could
output it using something like integer'image(it)?

To AV: I don't really know why it's necessary yet; sometimes my
subconcious mind works faster than my concious mind and I just have to
go with it. I can say though that:

-- Time and Time_Span are represented in 64-bit Duration value in
-- in nanoseconds. For example, 1 second and 1 nanosecond is
-- represented as the stored integer 1_000_000_001.

You never know, that depends on the underlying hardware and OS. Even under
the same hardware/OS there exist multiple time sources with their own
precision and accuracy.

So if a duration is represented as the stored INTEGER ... then I could
maybe use integer'image(duration), maybe?

what does this mean: type DURATION is delta implementation_defined
range implementation_defined;?

It varies from platform to platform

Is delta? what's delta?

Precision of a fixed-point type. See ARM 3.5.9.

with Ada.Real_Time; use Ada.Real_Time;
with Ada.Text_IO; use Ada.Text_IO;

procedure Test is
Start : Time := Clock;
Period : Duration;
type Seconds is delta 0.000_001 range -1.0E10 .. 1.0E10;
-- Microsecond precision type
begin
delay 0.5;
Period := To_Duration (Clock - Start);
Put_Line ("Duration delta on this computer = " & Float'Image
(Duration'Delta));
Put_Line (Duration'Image (Period) & "s");
Put_Line (Integer'Image (Integer (Period * 1000.0)) & "ms");
-- Be careful here, as it might overflow first in the multiplication
-- and then in conversion to integer
Put_Line (Float'Image (Float (Period)) & "s");
Put_Line (Seconds'Image (Seconds (Period)) & "s");
end Test;

--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
.

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