Re: [colorforth] shifted huffman trees

[Bill Parker <hodjiii@xxxxxxxxx>]

--- Mark Slicker <maslicke@xxxxxxxxxxx> wrote:

> This new tree should be regarded as an alternative
> to the 'comment', 'Capitalized', 'all caps' tags and
> the anti-space word.

Starting with a colorForth where 13/16 tags were used,
extending the character set frees up 2 tags.  If you
also use a special marker value in the upper bits to
indicate when numbers need a second word (something
I've toyed with and I think has been mentioned here
before) then you free up another 2 tags which gets you
down to the point where only 9/16 tags are used.

At that point, you could shrink the 'character' tags
with a Huffman-like encoding to add another data bit
(i.e. 29 bit character fields rather than 28).  It's
likely this makes the addition of an extended
character set a net gain (in terms of encoding).

For example, the tag bits of a word could become:

  111 extension
  110 variable
  101 comment
  100 define
  011 compile/cyan
  010 compile/green
  001 execute
11000 compile hex #
10000 execute hex #
01000 compile decimal #
00000 execute decimal #

I don't like this because there is no room for
expansion.  Does anybody see a good way to free up
00000 so that it is available to introduce additional
longer tag values?

> Huffman probabilities should influence the shape and
> balance of tree, but I haven't done that yet,

One of the reasons I just added one big block of
extended characters was that I was hard pressed to
come up with any reasonable 'frequency of use' by the
time I got to digits, capital letters and punctuation.

I'll be interested in seeing what you come up with for
this if you take the idea any further.

Bill


		
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