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From: Georg Bauhaus <sb463ba@l1-hrz.uni-duisburg.de>
Newsgroups: comp.lang.ada
Subject: Re: Ada way to read/write to character file
Date: Wed, 9 Jan 2002 16:12:13 +0000 (UTC)
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Michael Bode <m.g.bode@web.de> wrote:
: tmoran@acm.org writes:
:>   Given timing, error conditions, dropped lines, and the likelihood of
:> non-text data, I wonder how often you would actually want to do
:> "sequential text I/O" on an RS232 port. 
: 
: ...
: for a linear axis, 2 CCTV cameras and a scope. So I guess I will have to
: do that quite often :-).

The point is, I think, that Text_I/O is for text, where text refers
to the Ada notion of text, which includes lines, columns, pages and
what not; all of these give special meaning to some Character values
that you might not want to be that special for your devices.

So, when 0S services are called for, call the OS. Some package
producers have sets of subprograms to make things easier. If you
dig the archives for RS232/COM and Ada...

Moreover, if you want to live on the paranoia side, you might want
to consider it an assumption to consider OS's character
handling to be 8 bits chunk handling in sequential no-endian order.

And might it not be adventurous in some circumstances, like a
multi-access situation, to think that you would have to put hardware
in a required state just once at the start of a program?


Georg