Hi Mateusz,

The compression is a crude, back-referencing algorithm of my own design, called MVCOMP http://mateusz.fr/mvcomp/ Its compression rate is not spectacular, but it is not much worse than deflate, while being significantly simpler and faster.

I assume you enjoy designing algorithms, because there already are nice and lightweight existing ones, too :-) Some of this is topic of a thread about pondering compressed diskimage drivers for DOS on BTTR, sort of a VERY simple DOS-squashfs as distant cousin of doublespace, stacker and the like which would just compress each sector or cluster separately and store a table of compressed sector offsets for fast decompression. Back to the original topic of compressing AMB and similar content, the thread mentioned some suitable compression algorithms or packages :-)

I believe this should be of special interest to the FreeDOS project: the FreeDOS help is using AMB nowadays and the help file is painfully large.

As I prefer the ZIPped htmlhelp, I would say having compressed AMB helps the competition :-)

As a quick test I took the FDHELPEN.AMB file from the FreeDOS "AMBHELP 0.1d" package and repacked it with the compression-enabled AMB:

The manual decreased from 861K to 461K.
(for comparison, ZIP packs it to 380K)

That makes a big difference compared to the old AMB, thank you for the update :-)

Eric



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