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From: Dennis Hoppe <dennis.hoppe@hoppinet.de>
Newsgroups: comp.lang.ada
Subject: Re: Bit operations in Ada (endianness)
Date: Mon, 02 Jun 2008 15:27:32 +0200
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Date: 2008-06-02T15:27:32+02:00
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Hi,

I have another question regarding litte and big-endian. Is there
any way to declare, that the type

   type Bit_Field is array (Bit_Number) of Boolean;

is represented by litte or big-endian? Bit_Number is a generic
paremeter (mod <>). I figured out to set the endianness to
record types, but it does not work for the above array type.

I also wonder, if I can query the operating system via Ada,
which endianness it uses.

Thank you in advance,
   Dennis Hoppe



Simon Wright wrote:
> Ludovic Brenta <ludovic@ludovic-brenta.org> writes:
> 
>> Another alternative is Unchecked_Conversion:
>>
>> type Bit_Number is range 0 .. 31;
>> type Bit_Field is array (Bit_Number) of Boolean;
>> pragma Pack (Bit_Field);
>> function To_Bit_Field is
>>   new Ada.Unchecked_Conversion (Source => Interfaces.Unsigned_32,
>>                                 Target => Bit_Field);
> 
> Whether this does what you want may depend on whether the machine is
> big-endian (eg, SPARC, PowerPC etc) or not (Intel etc).