Re: ASCII to ASCII compression.

On Thu, 06 Jun 2024 17:25:37 +0100, Malcolm McLean wrote:

Not strictly a C programming question, but smart people will see the
relavance to the topicality, which is portability.
 
Is there a compresiion algorthim which converts human language ASCII
text to compressed ASCII, preferably only "isgraph" characters?
 
So "Mary had a little lamb, its fleece was white as snow".
 
Would become
 
QWE£$543GtT£$"||x|VVBB?

I'm afraid that you have conflicting requirements here. In effect,
you want to take an array of values (each within the range of
0 to 127) and
a) make the array shorter ("compress it"), and
b) express the individual elements of this shorter array with
   a range of 96 values ("isgraph() characters")

Because you reduce the number of values each result element
can carry, each result element can only express a fraction
(96/128'ths) of the corresponding source element. Thus,
with the isgraph() requirement, the result will take /more/
elements to express the same data as the source did.

However, you want /compression/, which implies that you want
the result to be smaller than the source. And, therein lies
the conflict.

Can you help clarify this for me?
--
Lew Pitcher
"In Skills We Trust"