editing binary (hexa) data

editing binary (hexa) data

[Peter Tury]

Hi,

I have strings(!) like this: "54 68 69 73 20 69 73 20 61 20 73 61 6D
70 6C 65 20 74 65 78 74 2E" and would like to edit them in
Emacs. However the above example is really "means": "This is a sample
text." So I would like to see this "meaning" while I edit it. If I
would have the text ("This is a sample text.") originally, then I
could use hexl-mode (hopefully it can be customized to group by bytes
and not by words). But now I don't know how to use it in my situation?
Or perhaps you know some other mode for me? (hexl-mode's UI would be
ideal if I could disable its original conversion at activation). (I
know I could make a small function to convert my "hexa string" into
"real" string before calling hexl-mode... but I hope you have a better
alternative.)

Thanks,
P

Re: editing binary (hexa) data

[Peter Dyballa]

Am 17.05.2007 um 11:09 schrieb Peter Tury:

> Or perhaps you know some other mode for me?

In GNU Emacs 22 you can use query-replace-regexp or replace-regexp to  
convert between ASCII and numeric:

	M-x replace-regexp RET \(.\) RET \,(string-to-number \1)  RET

or such and back with

	M-x replace-regexp RET \([1-9][0-9]\)  RET \,(string (+ ?a \1)) RET

There are some "invisible" spaces in the expressions, and they're not  
tested ...

--
Greetings

   Pete

A lot of us are working harder than we want, at things we don't like  
to do. Why? ...In order to afford the sort of existence we don't care  
to live.
                                    -- Bradford Angier

Re: editing binary (hexa) data

[David Kastrup]

Peter Dyballa <Peter_Dyballa@Web.DE> writes:

> Am 17.05.2007 um 11:09 schrieb Peter Tury:
>
>> Or perhaps you know some other mode for me?
>
> In GNU Emacs 22 you can use query-replace-regexp or replace-regexp to
> convert between ASCII and numeric:
>
> 	M-x replace-regexp RET \(.\) RET \,(string-to-number \1)  RET

You mean

 	M-x replace-regexp RET . RET \,(string-to-char \1)  RET

(returns Emacs' internal coding, not unicode or latin-1).

> or such and back with
>
> 	M-x replace-regexp RET \([1-9][0-9]\)  RET \,(string (+ ?a \1)) RET

	M-x replace-regexp RET [0-9]+  RET \,(string (+ ?a \#&)) RET

But why ?a?  Weird.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum

Re: editing binary (hexa) data

[Peter Dyballa]

Am 17.05.2007 um 19:24 schrieb David Kastrup:

> You mean
>
>  	M-x replace-regexp RET . RET \,(string-to-char \1)  RET

No, I meant that the text is first written in ASCII as "text" and  
then converted to ASCII values separated by spaces, i.e. the numbers  
and spaces we've seen.

>
> (returns Emacs' internal coding, not unicode or latin-1).

So it is not converting "ASCII" characters to their values?

>
>> or such and back with
>>
>> 	M-x replace-regexp RET \([1-9][0-9]\)  RET \,(string (+ ?a \1)) RET
>
> 	M-x replace-regexp RET [0-9]+  RET \,(string (+ ?a \#&)) RET
>
> But why ?a?  Weird.

You're right: this is nonsense! The numbers already *are* the ASCII  
values (and not the first, second, third ... letter, and the smallest  
letter is, of course, capital A!), so it's not necessary to add the  
smallest letter's ASCII value to the supposed ordinal. And two digits  
are not enough for all ASCII characters, since d already has 100 in  
decimal!

Why are you using ``\#&´´? Isn't \# meaning the back-reference?

--
Mit friedvollen Grüßen

   Pete

A child of five could understand this!  Fetch me a child of five.