Re: Hi byte and Lo Byte Question

[Peter Dulimov <pedu@eraseme.systems.saab.se>]

This is a really good idea.
I have spent a lot of time doing this manually, and inefficiently (in terms of
produced code, as well as the speed at which I produce it), in Ada83 (so not
even modular types available.)
Also, the original poster's problem --- switching byte order --- becomes easy.

Cheers,

Peter Dulimov.

Marin David Condic wrote:

[snip - stuff deleted]

> Here's a proposition worth discussing:
>
> In a lot of embedded apps and/or other apps that need to deal with things
> like communication streams, it would be very handy to be able to easily
> translate whatever data you have into raw bytes or turn raw bytes into the
> data you want. You typically need to do this efficiently and don't want to
> move the data. You can certainly get there with Unchecked_Conversion, but
> this can be a pain in the ASCII and might be inefficient - requiring the
> data to be moved. You can also get there by laboriously creating your own
> overlays - but this can rewuire a lot of declaring if you have a lot of
> things you want to treat as raw bytes.
>
> What about an attribute of any type that yields an array of
> Ada.Streams.Stream_Element_Array ? Similarly, going in the other direction:
>
> for X in My_Type'Raw_Data (My_Data)'Range loop
>     Some_Storage_Element := My_Type'Raw_Data (My_Data) (X) ;
> end loop ;
>
> or
>
> Some_Field := My_Type'Overlay (Some_Stream_Element_Array).Other_Field ;
>
> Maybe it should be an attribute of an Object rather than a Type? Don't know
> what can be done about safety in the event that the sizes don't line up, but
> I'll leave that to the compiler guys.
>
> I'm not fussy about the details (like the names) but it sure would be nice
> to have a means of very easily, efficiently and quickly treating any object
> as a stream of bytes - with the caveat being that I've just removed the
> safety net (as with Unchecked_Conversion) and I can now royally shoot myself
> in the foot.
>
> Comments?
>
> MDC