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-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@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/ass... https://stackoverflow.com/questions/759707/efficient-way-of-storing-huffman-...
Gerd
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