From: Jos De Laender <De_Laender-De_Winter@village.uunet.be>
Subject: Newbie question : types , representation
Date: 1999/08/22
Date: 1999-08-22T00:00:00+00:00 [thread overview]
Message-ID: <37BFC251.601ADF8F@village.uunet.be> (raw)
Hi,
I'm trying to learn ADA on my own.
My background is C programming (sorry ;-) ) and VHDL hardware
programming. The latter helps a lot , as VHDL inherited a lot of ADA.
I'm having trouble with following very simple problem , at least in
doing it portable and clean.
In base64 decoding , each ASCII character must be translated to 6 'bit'.
4 characters translate then to 3 bytes. The problem and algorithms are
trivial. In C I could do it within 5 minutes.
It would involve some bitmanipulation (shifting , anding , oring ) on
the character itself and then outputting. That's it.
However, what's unclear is how to do this in ADA types : A character
cannot be bit manipulated , and so needs some explicit translation to a
'byte' or something.
How is this usually done ? I would guess to use a modular type 2**8 ? If
I declare such a type , and I want a byte , is this guaranteed by 2**8
or do I have explicitly to attribute it with a 'for Byte'size use 8' ?
Also I will need some kind of assignment to that modular type, say aVar
:= 2#00000011#. This will assign the value 3 to aVar ? Is this
guaranteed to have that bit pattern ? Or could I imagine a (probably
exotic) machine on which 3 is represented with another bit pattern ?
Does ADA guarantee ?
If I output aVar with a write function , is the bitpattern guaranteed ?
Thanks for all clarifications.
Jos
next reply other threads:[~1999-08-22 0:00 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-08-22 0:00 Jos De Laender [this message]
1999-08-22 0:00 ` Newbie question : types , representation Robert Dewar
1999-08-23 0:00 ` Wolfgang Jeltsch
1999-08-24 0:00 ` tmoran
1999-08-24 0:00 ` jdla
1999-08-24 0:00 ` Matthew Heaney
1999-08-24 0:00 ` Jos De Laender
1999-08-24 0:00 ` Brian Rogoff
1999-08-25 0:00 ` Jos De Laender
1999-08-22 0:00 ` Martin Dowie
1999-08-22 0:00 ` Wilhelm Spickermann
1999-08-23 0:00 ` Martin C. Carlisle
1999-08-23 0:00 ` Simon Wright
[not found] ` <37C621F3.C6C0DC3A@acenet.com.au>
1999-08-27 0:00 ` tmoran
1999-08-27 0:00 ` Florian Weimer
1999-08-27 0:00 ` David C. Hoos, Sr.
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