Re: copying data between memory locations

[Martin Krischik <krischik@users.sourceforge.net>]

jef.mangelschots@gmail.com schrieb:

> In our current design, we have a package that maintains a list of
> descriptors of various buffers in the application. We don't want to
> know their datatypes or how to write data into them. We only want to
> maintain a physical address of them and use that address to directly
> write data into these buffers (this data comes out incoming packets
> over the network).
> 
> In C, this is very straightforward and use the address as a pointer
> and simply copy the packet into the memory location.

straightforward and highly dangerous.

> I can't figure out a way to do this in Ada (at least not Ada83).

You just have not found the right features yet. Suggested reading:

http://en.wikibooks.org/wiki/Ada_Programming/Types/access#Access_vs._System.Address
http://en.wikibooks.org/wiki/Ada_Programming/Type_System#Address_conversion
http://en.wikibooks.org/wiki/Ada_Programming/Type_System#Overlays

and from the reference manual:

http://www.adaic.com/standards/05rm/html/RM-13-7-2.html#I4643
http://www.adaic.com/standards/05rm/html/RM-13-3.html#I4496

As you can see (once you read the articles) you have even got two
options open and now you are left with choosing the right one ;-).

Martin

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Ada programming at: http://ada.krischik.com