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From: "Vinzent Hoefler" <0439279208b62c95f1880bf0f8776eeb@t-domaingrabbing.de>
Newsgroups: comp.lang.ada
Subject: Re: How do I write directly to a memory address?
Date: Thu, 10 Feb 2011 18:48:40 +0100
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Date: 2011-02-10T18:48:40+01:00
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J-P. Rosen wrote:

> Le 09/02/2011 23:25, Vinzent Hoefler a =C3=A9crit :
>>> No. They are just used to write left to right.
>>
>> Yes, but as you probably know, the number system is - arabic and ther=
e
>> the text-direction is "rtl".
>
> That's because you are insisting of considering that every machine wor=
d
> is a number. It is not. It just a set of bits.

Yeah. I remember Turbo-Pascal sets and an associates discussion in the
FreePascal mailing list where someone complained that the order of the
bits changes with the endianess. In such a case the bit-numbering indeed=

is more or less meaningless (and should be declared by convention),
because it's not associated with some numeric value.

(Yet, to be a really nit-picking a**hole, the original question was
about the "third bit in a byte", and I consider "byte" an integral
type, or "number".)

>> I know. Unfortunately, still some compilers (especially the one we're=

>> using) do not support that. I don't remember the exact error message,=

>> but it was somewhere along the lines of "non-default bit-order not
>> supported".
>>
> Just curious, which one is it?

The opposite of red valleys. ;)

> I'm surprised that a compiler is unable
> to compute 31-N.

I should probably have tried it again today to tell the precise
problem. I just remember that the code compiled with GNAT for both
little and big endian targets, but the target compiler complained
if a bit-order attribute was given.


Vinzent.

-- =

You know, we're sitting on four million pounds of fuel, one nuclear weap=
on,
and a thing that has 270,000 moving parts built by the lowest bidder.
Makes you feel good, doesn't it?
   --  Rockhound, "Armageddon"