Re: md5 checksum of a img file, or get the value of 100th byte

[Ted Zlatanov <tzz@lifelogs.com>]

On Fri, 06 Jun 2008 19:33:40 +0300 Eli Zaretskii <eliz@gnu.org> wrote: 

>> From: Ted Zlatanov <tzz@lifelogs.com>
>> Date: Fri, 06 Jun 2008 09:44:57 -0500
>> 
>> On Thu, 05 Jun 2008 22:17:02 +0300 Eli Zaretskii <eliz@gnu.org> wrote: 
>> 
EZ> Reading the file into a buffer and then working on that buffer is one
EZ> of the most efficient operations in Emacs.  After all, this is the
EZ> most basic operation of any text editor, so it must be heavily
EZ> optimized.
>> 
>> Not if the file is large :)

EZ> Yes, even if the file is large.

EZ> Note, I'm talking about Emacs, not about any computer program in
EZ> general.

I thought you meant the OP should just read the whole file into the
buffer, which is a bad idea for large files.  Sorry.

>> I'd like to see a 'sliding editing window' for large files but I
>> think it would require changes at the C level.

EZ> ??? insert-file-contents already can read only a portion of a file.
EZ> See its doc string.

I know about that.  I'd like to be able to open a 1 GB file in Emacs and
view just a piece at a time, in a sliding window.  I am not aware of
functionality to do this, and it's hard to do it efficiently because
every save is so painful, not to mention selecting the whole buffer and
other normally simple operations.  Read-only may be somewhat OK but lots
of basic commands will need to be advised or overridden.

Ted