Date   : Sat, 26 Aug 2006 01:44:20
From   : jgh@... (Jonathan Graham Harston)
Subject: Re: Hard disk backup - another challenge

>Message-ID: <4e5b104fd8info@...>

Sprow <info@...> wrote:
> > Why not use Packbits?
>
> Indeed, that's equally applicable, and I'm sure there are a good number of
> other algorithms which are lightweight (for handy BASIC implementation) and
> taylored to the typical contents of a harddisc.
>
> > by the ten bytes of data, which means you're only adding another byte to
> > the data. Only a ten percent increase, versus 100% for RLE.
>
> That would be an especially lame RLE implementation. Reread my random

I've not done anything with SerLink since 2000 when I got an A5000
on the network which removed the requirement to transfer data via
the serial link. Checking the code it does use just such a "lame"
RLE implementation!

01 02 03 04 05 gets encoded as 01 01 01 02 01 03 01 04 01 05 ! but
is assumes the program at the other end has examined the file it's
about to send and and decided to use RLE if it actually would be
better than not using RLE.

I might dig out my Arc-To-Beeb serial lead and change it to use
PackBits so it can dynamically RLE data instead of deciding it on
a per-file basis.

Though, if anybody wants the source to play with, they can have
it.


--
J.G.Harston - jgh@...                - mdfs.net/User/JGH
BBC BASIC for Windows and Internationalisation
  See http://mdfs.net/Software/BBCBasic/Windows/ProgTips