Re: 64bit access to an array of 8bit values

["Warren W. Gay VE3WWG" <ve3wwg@home.com>]

David C. Hoos, Sr. wrote:

> How about something like this?
> 
...

>    function Value (Index : Ram_Range) return Interfaces.Unsigned_64
>    is
>       Result : Interfaces.Unsigned_64;
>       for Result'Address use Ram (Index)'Address;
>    begin
>       return Result;
>    end Value;

I don't think you'll find this particularly portable. Even if

the compiler allows it, on some UNIX (for example) platforms
you may get a SIGBUS error if the Index value is not on a word
boundary (some CPUs like SPARC and other big endian machines
seem to come to mind in this regard).

There is another nit-pick with regards to safety if you try
using Index values that would address the last 3 bytes of the
available "RAM", returning a 4-byte value.


-- 
Warren W. Gay VE3WWG
http://home.cogeco.ca/~ve3wwg