Re: xor

[Michael Moeller <mic2@t-online.de>]

On Tue, 27 Mar 2012, Dmitry A. Kazakov wrote:

> On Tue, 27 Mar 2012 21:09:02 +0100, Michael Moeller wrote:
>
>> I have to read in what in C is called an unsigned byte,
>
> C does not have it. [unsigned] char maybe?
>
> In Ada there is a type Unsigned_8 declared in the package Interfaces.
>
>> which in fact is
>> a stream of bytes without any interpretation as a symbol.
>
> That depends on the operating system and the file type.
>
>> In addition it would be nice to call something like 'fstat' to get the
>> size of file in advance instead of checking every byte for EOF.
>
> In Ada you don't need that. You just read file until End_Error exception is
> propagated. This is more efficient (no look ahead) and more portable too.
>
> Here is an example of reading out a file in Ada using stream interface:
>
>   http://rosettacode.org/wiki/Bitmap/Read_a_PPM_file#Ada
>
> It uses Character type, which is close to the way one programs in C.
> Character'Pos (x), where x is of Character is a number 0..255.
>
> You can also use Interfaces.Unsigned_8 instead of Character, no difference.
>
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de
>
First, this Unsigned_Byte_T'Read thing worked. Thanks again.

Of course it's unsigned char in plain C. My fault.

I'm dealing with cipher stuff at the moment. I know for sure how
big the file is. Any other size will raise an error at runtime.
In addition there is no EOF, which brings me to the next question:

How can I prevent Ada from attaching '0x0a' to the end of the file?

Regards,
Michael