Re: GNAT Ada.Streams Bug?

["Warren W. Gay VE3WWG" <ve3wwg@NoSpam.cogeco.ca>]

Simon Wright wrote:
> "Warren W. Gay VE3WWG" <ve3wwg@NoSpam.cogeco.ca> writes:
>>I am not concerned at all about the efficiency of this case, as you
>>read the partition 4 times at boot time (less if you have fewer
>>disks).  I know however, that you were stating the more general
>>case.
>>
>>It is disappointing to learn that basically Ada95 is "portability
>>busted" when it comes to Ada.Streams. As Randy (I think) mentioned
>>in the AI link, it is very difficult to adapt a stream to external
>>formats - more impossible to be compiler independent at the same
>>time. Since I am trying to interface a stream to the boot sector,
>>this becomes a real problem that I'll have to "work around".
> 
> So the AI lets you make the streaming portable provided that
> everything is a multiple of Stream_Element'Size (and, I guess, all the
> participants are of the same endianness).

I suppose I have always considered everything to be a multiple of
Stream_Element'Size anyway. But you are right in that you could
have types in odd bitwise sizes. My expectations were
set lower than yours ;-)

> If those conditions are met, you have what looks like a more
> convenient way of expressing representations. Otherwise, it'll have to
> be the hard way .. I must say it wouldn't have occurred to me to
> expect a Stream to meet your requirements. But we progress by meeting
> needs, and someone has to express them!

With GNAT, I simply need to stick to multiples of 2,4,8 etc.,
and then their streams I/O works fine (apart from arrays of
bytes).

I got around my problem by separating the head from sector
& cylinder (24 bits => 8 + 16). This works fine, since we're
dealing with a 1 and 2 byte values.

Warren.