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From: Richard Harnden <richard.nospam@gmail.invalid>
Newsgroups: comp.lang.c
Subject: Re: ASCII to ASCII compression.
Date: Fri, 7 Jun 2024 20:06:09 +0100
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On 07/06/2024 19:49, Malcolm McLean wrote:
> On 07/06/2024 13:52, Mikko wrote:
>> On 2024-06-07 09:00:57 +0000, Malcolm McLean said:
>>
>>> Yes, but Huffman is easy to decode. It's the sort of project you give 
>>> to people who have just got past the beginner stage but aren't very 
>>> experienced programmers yet, whilst implementing Lempel-Ziv is a job 
>>> for someone who knows what he is doing.
>>>
>>> Because the lines will often be very short, adaptive Huffman coding 
>>> is no good. I need a fixed Huffman table with 128 entries for each 7 
>>> bit value plus one for "stop". I wonder if any such standard table 
>>> exists.
>>
>> You don't need a standard table. You need statistics. Once you have the
>> statistics the table is easy to costruct with Huffman's algorithm.
>>
> No you do. The text might be very short, like "Mary had a little lamb", 
> and you will compress it because you know that you are being fed 
> meaningful ASCII. For example even this tiny fragment contains the 
> letter "e", which would have a short Huffman code. And four a's and two 
> t's, which are the third and the second most commn letters. So it should 
> compress.
> 
> And we're compressing each line independently, and choosing a visually 
> distinctive ASCII character as the line break. So anyone seeing the 
> compressed data will immediately be able to home in on the line breaks, 
> and will be able to fix any corruption without special tools.
> 
> And you have a standard table which never changes. And so that makes the 
> decompressor much easier to write.

Will your babyx be able to handle, say, utf-8?

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