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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: relearning C: why does an in-place change to a char* segfault?
Date: Mon, 12 Aug 2024 02:55:01 -0700
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Richard Damon <richard@damon-family.org> writes:

> On 8/3/24 10:58 PM, Keith Thompson wrote:
>
>> Lawrence D'Oliveiro <ldo@nz.invalid> writes:
>>
>>> On Sat, 03 Aug 2024 17:07:37 -0700, Keith Thompson wrote:
>>>
>>>> ... general compression isn't something I've seen ...
>>>
>>> I recall Apple had a patent on some aspects of the ?PEF?
>>> executable format that they created for their PowerPC machines
>>> running old MacOS.  This had to do with some clever instruction
>>> encodings for loading stuff into memory.
>>
>> Is that relevant to what I asked about?
>>
>> What I had in mind is something that, given this:
>>
>>      static int buf = { 1, 1, 1, ..., 1 }; // say, 1000 elements
>>
>> would store something less than 1000*sizeof(int) bytes in the
>> executable file.  I wouldn't be hard to do, but I'm not convinced
>> it would be worthwhile.
>
> I vaguely seem to remember an embedded format that did something like
> this.  The .init segement that was "copied" to the .data segement has
> a simple run-length encoding option.  For non-repetitive data, it
> just encoded 1 copy of length n.  But it could also encode repeats
> like your example.  When EPROM was a scarce commodity squeezing out a
> bit of size for the .init segment was useful.
>
> My guess that since it didn't persist, it didn't actually help that
> much.

Or maybe it helped back in the day, but since then technology has
changed and it doesn't help any more.