Hi Ticker,
my thought for the struct bytes was that the 1-bits might represent the
position of leafs, but
the bit counts don't match.
Gerd
________________________________________
Von: mkgmap-dev <mkgmap-dev-boun...@lists.mkgmap.org.uk> im Auftrag von Ticker
Berkin <rwb-mkg...@jagit.co.uk>
Gesendet: Sonntag, 19. Dezember 2021 10:12
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] [mkgmap-svn] Commit r572: MDR16 is
some kind of codebook.
Hi Gerd
It looks like the order of the letter patterns approaches canonical
Huffman (but not quite as far as I can see). With this, only the number
of codes of each length is required to form the tree.
The "struct for {level}" looks like 2 numbers. Both increasing as
levels go from 20 to 6. The first, a single byte from #00 to #3d - this
could be give the accumulated lengths at each level (but I didn't get
it to match). The second, variable length, from #000006 to #180c00 and
I've no idea what it could mean.
Levels 1 - 5 seem to be handled differently. with the repeat * 4,
repeat * 2, no repeat and the padding.
Ticker
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