Hi Ticker,
I looked at a few more old maps (donations from a mkgmap user)
with MDR16. They all seem to match the
pattern with the prefixes 0x0b, 0x09, and 0x07 and the repeating of information.
Maybe you get an idea what the rest means.
Gerd
________________________________________
Von: Gerd Petermann <gpetermann_muenc...@hotmail.com>
Gesendet: Donnerstag, 16. Dezember 2021 15:42
An: Development list for mkgmap
Betreff: AW: [mkgmap-dev] [mkgmap-svn] Commit r572: MDR16 is
some kind of codebook.
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
_______________________________________________
mkgmap-dev mailing list
mkgmap-dev@lists.mkgmap.org.uk
https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
--------- MDR 16 (decompression codebook Huffman tree) -------------------------
| | | Unknown 177 bytes:
000002ae | 000000 | be 02 15 12 0c 08 5d 00 | ¾.....].
000002b6 | 000008 | 00 00 12 00 06 00 00 11 | ........
000002be | 000010 | 06 0c 00 00 10 09 20 00 | ...... .
000002c6 | 000018 | 00 0f 0e 50 00 00 0e 14 | ...P....
000002ce | 000020 | e0 00 00 0d 1d 00 01 00 | à.......
000002d6 | 000028 | 0c 1e 80 01 00 0b 20 00 | ..?... .
000002de | 000030 | 03 00 0a 23 00 04 00 08 | ...#....
000002e6 | 000038 | 24 00 08 00 07 25 00 20 | $....%.
000002ee | 000040 | 00 06 28 00 0a 16 0b 16 | ..(.....
000002f6 | 000048 | 0b 16 0b 0b 55 0b 44 0b | ....U.D.
000002fe | 000050 | 48 0b 4b 0b 20 0b 47 09 | H.K. .G.
00000306 | 000058 | 4e 09 4e 09 4c 09 4c 09 | N.N.L.L.
0000030e | 000060 | 41 09 41 09 53 09 53 09 | A.A.S.S.
00000316 | 000068 | 49 09 49 09 52 09 52 09 | I.I.R.R.
0000031e | 000070 | 4f 09 4f 09 00 09 00 09 | O.O.....
00000326 | 000078 | 54 09 54 07 45 07 45 07 | T.T.E.E.
0000032e | 000080 | 45 07 45 22 30 39 3c 60 | E.E"09<`
00000336 | 000088 | c7 3e cf d4 34 35 36 37 | Ç>ÏÔ4567
0000033e | 000090 | c0 32 38 33 c4 ca db 2c | À283ÄÊÛ,
00000346 | 000098 | 28 31 c2 2f 29 2e d6 dc | (1Â/).ÖÜ
0000034e | 0000a0 | c8 51 cb 58 27 c9 59 46 | ÈQËX'ÉYF
00000356 | 0000a8 | 5a 4a 2d 56 57 50 42 43 | ZJ-VWPBC
0000035e | 0000b0 | 4d | M
--------- MDR 16 (decompression codebook Huffman tree) -------------------------
| | | Unknown 210 bytes:
000002a6 | 000000 | 42 03 15 16 10 08 77 00 | B.....w.
000002ae | 000008 | 00 00 16 00 06 00 00 15 | ........
000002b6 | 000010 | 06 18 00 00 14 0f 20 00 | ...... .
000002be | 000018 | 00 13 11 30 00 00 12 13 | ...0....
000002c6 | 000020 | 60 00 00 11 16 80 00 00 | `....?..
000002ce | 000028 | 0f 17 00 01 00 0e 18 00 | ........
000002d6 | 000030 | 02 00 0d 19 00 04 00 0c | ........
000002de | 000038 | 1a 00 18 00 0b 1f 00 20 | .......
000002e6 | 000040 | 00 0a 20 00 80 00 09 26 | .. .?..&
000002ee | 000048 | 00 80 01 08 2e 00 80 02 | .?....?.
000002f6 | 000050 | 07 32 00 00 04 06 35 00 | .2....5.
000002fe | 000058 | 0d 1a 0e 1e 0f 1e 0f 1e | ........
00000306 | 000060 | 0f 0b 42 0b 4c 0b 4f 0b | ..B.L.O.
0000030e | 000068 | 4d 0b 55 0b 49 0b 47 09 | M.U.I.G.
00000316 | 000070 | 53 09 53 09 52 09 52 09 | S.S.R.R.
0000031e | 000078 | 48 09 48 09 4e 09 4e 09 | H.H.N.N.
00000326 | 000080 | 20 09 20 09 54 09 54 09 | . .T.T.
0000032e | 000088 | 00 09 00 09 41 09 41 07 | ....A.A.
00000336 | 000090 | 45 07 45 07 45 07 45 9f | E.E.E.E?
0000033e | 000098 | b0 cf d2 d9 db 60 c2 ca | °ÏÒÙÛ`ÂÊ
00000346 | 0000a0 | cb cd d1 d4 da de c0 c1 | ËÍÑÔÚÞÀÁ
0000034e | 0000a8 | 3f d3 5f c8 22 2b 21 2c | ?Ó_È"+!,
00000356 | 0000b0 | c9 51 2f 26 27 df 58 4a | ÉQ/&'ßXJ
0000035e | 0000b8 | 59 37 39 38 30 36 32 33 | Y7980623
00000366 | 0000c0 | c4 34 2e 35 31 29 d6 dc | Ä4.51)ÖÜ
0000036e | 0000c8 | 56 28 2d 5a 50 43 57 4b | V(-ZPCWK
00000376 | 0000d0 | 44 46 | DF
-
_______________________________________________
mkgmap-dev mailing list
mkgmap-dev@lists.mkgmap.org.uk
https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
