Re: Real Time IO routines

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

andrew writes:
> On Oct 26, 1:36 pm, Ludovic Brenta <ludo...@ludovic-brenta.org> 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?
>>
>> --
>> Ludovic Brenta.
>
> To Ludovic:  Ahh, so if I had to define a universal_real I could
> output it using something like integer'image(it)?

No, because Integer is not a floating-point type.  You would use
Float'Image instead.  In light of what follows, I forgot to mention
that universal_real also converts to any fixed-point type implicitly.

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

No; Time and Time_Span are fixed-point types, not integer types.  You
should do:

Nanosecond : constant := 1.0E-9; -- there's your universal_real :)
type My_Fixed_Time is
  delta Nanosecond range 0.0 .. (2 ** 64 - 1) * Nanosecond;
for My_Fixed_Time'Size use 64;
function To_My_Fixed_Time is
  new Ada.Unchecked_Conversion (Source => Time; Target => My_Fixed_Time);

T : Time;
Image : constant String := My_Fixed_Time'Image (To_My_Fixed_Time (T));

(I just made that up; didn't try to compile it so caveat emptor).

> what does this mean:  type DURATION is delta implementation_defined
> range implementation_defined;?
> Is delta?  what's delta?

A fixed-point type.  See ARM 3.5.9.

-- 
Ludovic Brenta.