Hi Ticker,

the order of the chars seems to depend on the depth in the tree at which they 
appear.
Something like this happens beginning at offset 5c in MDR 16:
write 0x0b
write 1st value at depth 5
write 0x0b
write 2nd value at depth 5
write 0x0b
write 3rd value at depth 5
...
write 0x0b
write last value at depth 5

repeat 2 times:
write 0x09
write 1st value at depth 4
repeat 2 times:
write 0x09
write 2nd value at depth 4
...
repeat 2 times:
write 0x09
write last value at depth 4

repeat 4 times:
write 0x07
write 1st value at depth 3 (there is only one in this tree)

No prefix, no repeats for the rest:
write values at level depth 20
write values at level depth 19
...
write values at level depth 6

This decribes all bytes in MDR 16 from offset 5c to the end.

No idea yet what the prefixes mean.
Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-boun...@lists.mkgmap.org.uk> im Auftrag von Ticker 
Berkin <rwb-mkg...@jagit.co.uk>
Gesendet: Donnerstag, 16. Dezember 2021 10:04
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev]       [mkgmap-svn]    Commit  r572:   MDR16   is      
some    kind    of      codebook.

Hi Gerd

I found similar/same algos. I'm trying to thing of other ways that
might come up with what we see. I'll continue research.

Ticker

On Wed, 2021-12-15 at 20:18 +0000, Gerd Petermann wrote:
> Hi Ticker,
>
> do you have a link for me? None of the methods to store the tree that
> I found would produce such a data structure.
> This is what I found so far:
> https://web.stanford.edu/class/archive/cs/cs106b/cs106b.1208/assignments/assign6/warmup
> https://stackoverflow.com/questions/759707/efficient-way-of-storing-huffman-tree
>
> Gerd


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