Re: GNAT 4.4.5 Record Bit_Order Endian issues

[Stephen Leake <stephen_leake@stephe-leake.org>]

Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org> writes:

> On 01/21/2013 08:21 PM, Stephen Leake wrote:
>>
>> 2/2
>> R.C'Position
>>
>>                 {AI95-00133-01AI95-00133-01} If the nondefault bit
>>                 ordering applies to the composite type, and if a
>>                 component_clause specifies the placement of C, denotes
>>                 the value given for the position of the
>>                 component_clause; otherwise, denotes the same value as
>>                 R.C'Address - R'Address. The value of this attribute is
>>                 of the type universal_integer.
>>
>> Note the 'otherwise'; that's means the value is R.C'Address - R'Address
>> only if position is _not_ specified in a rep clause.
>
> No. This says
>
> if A and B then
>    D;
> else
>    E;
> end if;

Ah, missed that. I stand corrected. I did take symbolic algebra in
college - my professor would be disappointed ;).

So, this _never_ defines the meaning of the position given in a
component clause; it only defines the meaning of the 'Position
attribute. 

I suppose we could assume that 'Position always means the same thing as
the position specified in the component clause, but it would be better
if this (and 13.5.1) said that explicitly.

Actually, if we assume Cohen's paper applies, I believe it is still
R.C'Address - R'Address in the nondefault bit order case.

-- 
-- Stephe