						10 Feb 1994

Since version 0.1 was uploaded and announced, several people have
reported problems installing the DouBle driver. I believe, patch01
and individual assistance by email has solved their problems.

Unfortunately, I lost some of my email on Feb 6 and Feb 7 (my mistake;
it went to /dev/null by accident !) :(.
If you sent me email last week and got no reply:
1 - I apologize.
2 - Send it again; I WILL reply.

In particular someone wrote the following and I lost the return path/From
fields:

>Although I have no Linux handy (SS2 at work, XT at home) I decided to
>take a look at your compression code. Probably I'm not the first who
>asks you that, but why did you choose LZW? It is 1) patented;
>2) slow (especially for decompression); 3) non-optimal for on-the-fly
>compression (it adapts relatively slowly). You can say that LZRW1 is
>patented too, and its maximum compression ratio is less than LZW's,
>but as your blocks are of fixed length (4K), you can adapt it to
>be more suitable for your purposes (say, you probably will want to
>use 10-to-6 or 11-to-5 bit partitioning instead of regular 12-to-4
>bit for offset+length coding). And LZRW1 is definitely faster
>(esp. for decompression). As for patents, you can consider LZRW2, 3
>or modifications (LZRW1+RLE, etc.).


The reason I chose LZW is that I had it handy when I wrote my driver.
I had no idea it was patented; I found the algorithm in a book several
years ago. In fact I don't know much about compression.
I don't know much about device drivers either; it's my first one.

All I wanted was to put something together. However, I am open-minded,
and I hope the driver will be as well. It should be easy to add new
compression code and I realize the one I chose was probably not the best.
So if you, the author of this message (by the way you were the first and
only one to ask so far), or anybody else want to help you can at your
convenience:

- Get in touch with me (I'll do by very best not to trash my email again).

- Write the compression code of your choice for this driver and send
it to me so that I can include it.

- Send me more information (algorithms) on alternate compression techniques.

- Tell me where I can easily find more information on other techniques.

Of course, anybody having suggestions/questions on other parts of the driver
is also welcome to get in touch with me.

				Thanks for your help,

				Jean-Marc Verbavatz
