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From: Malcolm McLean <malcolm.arthur.mclean@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: ASCII to ASCII compression.
Date: Mon, 10 Jun 2024 22:52:31 +0100
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On 10/06/2024 21:28, Ben Bacarisse wrote:
> Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:
> 
>> On 10/06/2024 18:55, Ben Bacarisse wrote:
>>> Malcolm McLean <malcolm.arthur.mclean@gmail.com> writes:
>>>
>>>> We have a fixed Huffman tree which is part of the algorithm and optmised
>>>> for ASCII. And we take each line otext, and comress it to a binary string,
>>>> using the Huffman table. The we code the binary string six bytes ar a time
>>>> using a 64 character dubset of ASCCI. And the we append a special character
>>>> which is chosen to be visually distinctive..
>>>>
>>>> So the inout is
>>>>
>>>> Mary had a little lamb,
>>>> it's fleece was white as snow,
>>>> and eveywhere that Mary went,
>>>> the lamb was sure to. go.
>>>>
>>>> And we get the output.
>>>>
>>>> CVbGNh£-H$£*MMH&-VVdsE3w2as3-vv$G^&ggf-
>>> It would be more like
>>> pOHcDdz8v3cz5Nl7WP2gno5krTqU6g/ZynQYlawju8rxyhMT6B30nDusHrWaE+TZf1KdKmJ9Fb6orB
>>> (That's an actual example using an optimal Huffman encoding for that
>>> input and the conventional base 64 encoding.  I can post the code table,
>>> if you like.)
>>>
>>>> And if it shorter or not depends on whether the fixed Huffman table is any
>>>> good.
>>> If I use a bigger corpus of English text to derive the Huffman codes,
>>> the encoding becomes less efficient (of course) so those 110 characters
>>> need more like 83 base 64 encoded bytes to represent them.  Is 75% of
>>> the size worth it?
>>> What is the use-case where there is so much English text that a little
>>> compression is worthwhile?
>>>
>> The FileSystem XML files. They are uncompressed, and as you can take in
>> entire folders, they can be very large.
> 
> I don't know what the XML file system is for either so explaining one by
> the other doesn't help.  I was hoping for a use -- a user story -- that
> would help me understand what the point of all this is.
> 
> Tell me as a story: A user wants to ... what?  And having a directory of
> large text files in a structured XML text helps because they can
> ... what?  And if they were a quarter of the size it would be better
> because ... why?
> 

The idea is that you package up a directory, and use it as an embedded 
resource on inside the application. So it has access to an internal 
filing system. That's the point of the Baby X Filesystem sub component, 
BabyXFS, which I am currently adding to the resource compiler 
repository. And that what this stage of the hobby project is all about.

-- 
Check out my hobby project.
http://malcolmmclean.github.io/babyxrc