Re: setting 'Size and unchecked conversion safe here?

[Marius Amado Alves <amado.alves@netcabo.pt>]

On 12 Feb 2005, at 06:55, Martin Krischik wrote:

> Marius Amado Alves wrote:
>
>>>    ARM 13.9(5 .. 11) says
>>> "If all of the following are true,
>>>  ...
>>>  S'Size = Target'Size
>>
>> I know. This happens, because I forced the access type to be 64-bit,
>> same as the modular. What I'm not sure about is whether the unused 32
>> bits are harmless or not (by definition). Thanks.
>
> There are not harmless since there is no requironment to set them to
> 16#0000000#.

If there were such a requirement is there a simple way to specify it?

> In order to help you we have to know why it is that the access is 32 
> bit and
> the modular 64. I can only guess it is for some compatiblity reason - 
> but
> what do you need to keep compatible?

The access type is 32 bits because the compiler says so.
The modular 64 is my choice to represent small values (integers, 
floats, tiny strings, access values) in the vertices of a Mneson graph:

    type Vertex is record
       Tip : Natural_16;
       Cue : Modular_64;
    end record;
    for Vertex'Size use 80;
    pragma Pack (Vertex);

I know this might be incompatible with some unusual architectures but 
I'm prepared to deal with that when and if the time comes.