On 01/07/2026 07:26, E. C. Masloch via Freedos-devel wrote:
On at 2026-06-30 12:06:43 +0000, Crefelean Nicolae via Freedos-devel
<[email protected]> wrote:
Hi,
About the floppy edition: please consider creating a special set for pre-386
PCs by using LZ4_8088.
Link: http://www.oldskool.org/pc/lz4_8088
...
On the licensing side, it's basically FOSS, but you can read that bit on the
URL I mentioned.
I disagree, it uses a bespoke license that I think is incompatible with the
GPL. The license text in full reads:
...
The remainder of this message is about building a kernel file that's lDOS
flavour, containing a FreeDOS kernel.
...
test$ ls -lgG */*/freedos.{com,sys}
-rw-r--r-- 1 67472 Jun 30 20:01 tmp/lz4/freedos.com
-rw-r--r-- 1 63712 Jun 30 20:01 tmp/lz4/freedos.sys
-rw-r--r-- 1 56624 Jun 30 20:01 tmp/lz/freedos.com
-rw-r--r-- 1 52864 Jun 30 20:01 tmp/lz/freedos.sys
-rw-r--r-- 1 60176 Jun 30 20:01 tmp/sa2/freedos.com
-rw-r--r-- 1 56416 Jun 30 20:01 tmp/sa2/freedos.sys
test$
These are the LZ4, LZSA2, and LZMA-lzip compression methods. ...
Hmm, how does ZX0 compare? This one's fairly common in the demoscene these
days, and actually is open source / free software:
https://github.com/einar-saukas/ZX0 [compressor + reference decompressors, BSD
3-clause licence]
https://github.com/emmanuel-marty/unzx0_x86 [8088 asm decompressor, Zlib
licence]
Although LZSA2 does look like another good option at least in terms of speed.
... ah who am I kidding, I can test this myself, thanks for posting the link to
the build with the uncompressed files...
.q is testing the quick non-optimal compression which is still pretty slow to compress,
and .b is testing backwards compression, "delta=" is what I got from the
compressor output and I think for the backwards variants you have to start unpacking at
least this many bytes after the end of the uncompressed result:
86112 fdosu.com
58842 fdosu.com.q.zx0 [delta=2]
56541 fdosu.com.b.zx0 [delta=3]
56395 fdosu.com.zx0 [delta=2]
82352 fdosu.sys
53607 fdosu.sys.b.zx0 [delta=3]
53450 fdosu.sys.zx0 [delta=3]
So... competitive with LZMA-lzip, but should also decompress quickly? Maybe I
should do what I did with my own packer+unpacker and apply it to V8 Power Tools
then compare it on an emulated 286 in 86Box - the UPX decompression was
painfully slow.
Then again, that's more of a concern for loading and running programs from
disk, decompressing the kernel is something that only happens once per boot so
something a little slower should be OK.
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