Ada.Calendar Question

Ada.Calendar Question

[awdorrin]

I have been looking at the Ada.Calendar and Ada.Real_Time packages, trying to update some old Ada code, which interfaces to C.

How do I access the 'Conversion_Operations' package defined within Ada.Calendar?

I have been trying to make use of:
 Conversion_Operations.To_Ada_Time( Unix_Time : Long-Integer );
 Conversion_Operations.To_Struct_Timespec()
and
 Conversion_Operations.To_Duration()

I have seen the C specific versions in Ada.Calendar.Conversion, but those all use the Interfaces.C package types.

Re: Ada.Calendar Question

[Adam Beneschan]

On Friday, July 20, 2012 10:18:22 AM UTC-7, awdorrin wrote:
> I have been looking at the Ada.Calendar and Ada.Real_Time packages, trying to update some old Ada code, which interfaces to C.
> 
> How do I access the 'Conversion_Operations' package defined within
> Ada.Calendar?

This is defined in the *private* part of one implementor's implementation of Ada.Calendar.  They could easily change the semantics of those routines in a future release.  So attempting to access them seems like a very bad idea.

                          -- Adam

Re: Ada.Calendar Question

[awdorrin]

I finally realized that these nested packages are tagged private. Now it makes sense.

It looks like the 'easiest' way for me to get from the stored 'seconds' and 'nanoseconds' is to do the following:

procedure Example( sec : in Integer; nSec : in Integer) is

  T : Ada.Calendar.Time;

begin

  T := Ada.Calendar.Conversions.To_Ada_Time(0) -- to get epoch
    + Ada.Calendar.Conversions.To_Duration( long(sec), long(nSec));

  Put_Line( Ada.Calendar.Formatting.Image(
    Date => T, Include_Time_Fraction => True, 
    Time_Zone => Ada.Calendar.Time_Zones.UTC_Time_Offset(T) );

end Example;

The 'To_Duration' is a bit annoying, requiring withing the 'Interfaces.C' package for the 'long' type, but it does work fine.

Re: Ada.Calendar Question

[Simon Wright]

awdorrin <awdorrin@gmail.com> writes:

> procedure Example( sec : in Integer; nSec : in Integer) is
>
>   T : Ada.Calendar.Time;
>
> begin
>
>   T := Ada.Calendar.Conversions.To_Ada_Time(0) -- to get epoch
>     + Ada.Calendar.Conversions.To_Duration( long(sec), long(nSec));

It depends what you mean by 'epoch'. If it's 1 Jan 1970 (as for Unix),
then you should be aware that at the change to Ada 05 GNAT changed
representations so that 1 Jan 1970 is no longer stored as 0.

      use type Ada.Calendar.Time;
   begin
      T := Ada.Calendar.Time_Of (Year => 1970, Month => 1, Day => 1)
             + Duration (sec) + Duration (nSec) / 1.0e9;

Re: Ada.Calendar Question

[awdorrin]

On Friday, July 20, 2012 2:51:23 PM UTC-4, Simon Wright wrote:
> 
> It depends what you mean by 'epoch'. If it's 1 Jan 1970 (as for Unix),
> then you should be aware that at the change to Ada 05 GNAT changed
> representations so that 1 Jan 1970 is no longer stored as 0.

Since I'm interfacing to C routines, I do mean 1-Jan-1970.

I do like your suggestion, it is much cleaner and I don't need to include either the Interfaces.C or Ada.Calendar.Conversions packages.

Thanks!