[REBOL] Re: compression
From: ryanc:iesco-dms at: 12-Sep-2001 17:01
Just out the curiousity I had to read the patend. I wonder if it still would
apply if you did the process backwards?
Strangely, as I read though it, I was somehow reminded of a night I filled a
super soaker with tequila.
--Ryan
High speed data compression and decompression apparatus and method
Abstract
A data compressor compresses an input stream of data character signals by
storing in a string table strings of data character signals encountered in the
input stream. The compressor searches the input stream to determine the longest
match to a stored string. Each stored string comprises a prefix string and an
extension character where the extension character is the last character in the
string and the prefix string comprises all but the extension character. Each
string has a code signal associated therewith and a string is stored in the
string table by, at least implicitly, storing the code signal for the string,
the code signal for the string prefix and the extension character. When the
longest match between the input data character stream and the stored strings is
determined, the code signal for the longest match is transmitted as the
compressed code signal for the encountered string of characters and an extension
string is stored in the string table. The prefix of the extended string is the
longest match and the extension character of the extended string is the next
input data character signal following the longest match. Searching through the
string table and entering extended strings therein is effected by a limited
search hashing procedure. Decompression is effected by a decompressor that
receives the compressed code signals and generates a string table similar to
that constructed by the compressor to effect lookup of received code signals so
as to recover the data character signals comprising a stored string. The
decompressor string table is updated by storing a string having a prefix in
accordance with a prior received code signal and an extension character in
accordance with the first character of the currently recovered string.
Gregg Irwin wrote:
> << I'd be interested in how to do the equivalent of a bitblt in REBOL, or to
> know what is the most efficient way to manipulate images. >>
>
> Hmmm, maybe I just found it. It looks like you can use an image in the draw
> dialect. Dang, every time I think I've found something that should be hard
> to do, there's an easy solution.<g>
>
> --Gregg
>
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--
Ryan Cole
Programmer Analyst
www.iesco-dms.com
707-468-5400
