Re: Arrays in Ada 2012

["Randy Brukardt" <randy@rrsoftware.com>]

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:oh88l2$gsf$1@gioia.aioe.org...
> On 06/06/2017 22:56, Randy Brukardt wrote:
>
>>         Current := Current + Long_Long_Integer'Size/Storage_Unit;
>
> A bit OT question.
>
> I always use rounding in the corresponding cases
>
>    (Long_Long_Integer'Size + Storage_Unit - 1) / Storage_Unit;
>
> Is this an overkill from the point of view the permissions RM gives to 
> array implementation?

The definition of 'Size is stupid, so you need rounding like that to be 
portable. It's probably not necessary for base types, but if you had
    (Natural'Size / Storage_Unit)
you would get the wrong answer (Ada requires Natural'Size to be one less 
than Integer'Size, so it usually is 15 or 31 or 63).

Probably a better solution is to use 'Object_Size for such expressions, but 
that is only portable to Ada 202x compilers (for which none exist yet for 
obvious reasons). Object_Size usually will be a multiple of the storage 
unit; that's the Implementation Advice for it, but of course some 
implementation could ignore that in some circumstance.

                              Randy.