[mkgmap-dev] [mkgmap-svn] Commit r572: MDR16 is some kind of codebook.
From Gerd Petermann gpetermann_muenchen at hotmail.com on Tue Dec 21 16:49:29 GMT 2021
Hi Ticker, looks good. With your hints I was able to write a patch for MdrDisplay that seems able to decode compressed mdr15 for my maps which have mdr 16 section. Maybe you have another map... It also changes some details for mdr 30/31 and 32/33. Open problem is the length of the gap between the end of data for the 6th level and the first bytes for level 5 (prefix 0b). I see either 7 or 12 or 5 bytes. Check the code that calculdates value for variable skip. The values might not at all depend on the depth of the tree. Code is not at all optimized, it just started to work for me. Lots of bytes in MDR 16 are ignored. Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Gerd Petermann <gpetermann_muenchen at hotmail.com> Gesendet: Montag, 20. Dezember 2021 11:29 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] [mkgmap-svn] Commit r572: MDR16 is some kind of codebook. Hi Ticker, yes, with your theory I found errors in my code. Here's the corrected version // depth 3, prefix 0x07 addHuffmanNode("111", 'A'); // depth 4, prefix 0x09 addHuffmanNode("0111", '\0'); // 0x00 addHuffmanNode("1000", ' '); //0x20 addHuffmanNode("1001", 'E'); addHuffmanNode("1010", 'N'); addHuffmanNode("1011", 'O'); addHuffmanNode("1100", 'I'); addHuffmanNode("1101", 'R'); // depth 5, prefix 0x0b addHuffmanNode("00101", 'C'); addHuffmanNode("00110", 'S'); addHuffmanNode("00111", 'D'); addHuffmanNode("01000", 'T'); addHuffmanNode("01001", 'M'); addHuffmanNode("01010", 'V'); addHuffmanNode("01011", 'J'); addHuffmanNode("01100", 'K'); addHuffmanNode("01101", 'L'); // depth 6 addHuffmanNode("000101", 'G'); addHuffmanNode("000110", 'Z'); addHuffmanNode("000111", 'U'); addHuffmanNode("001000", 'P'); addHuffmanNode("001001", 'B'); // depth 7 addHuffmanNode("0000110", 'H'); addHuffmanNode("0000111", '1'); addHuffmanNode("0001000", '2'); addHuffmanNode("0001001", '.'); // depth 8 addHuffmanNode("00000011", '5'); addHuffmanNode("00000100", '6'); addHuffmanNode("00000101", '-'); addHuffmanNode("00000110", '7'); addHuffmanNode("00000111", '3'); addHuffmanNode("00001000", '8'); addHuffmanNode("00001001", '9'); addHuffmanNode("00001010", '0'); addHuffmanNode("00001011", '4'); // depth 9 addHuffmanNode("000000010", 'F'); addHuffmanNode("000000011",','); addHuffmanNode("000000100", '('); addHuffmanNode("000000101", ')'); // depth 10 addHuffmanNode("0000000011", '*'); // depth 11 addHuffmanNode("00000000011", 'Y'); addHuffmanNode("00000000100", '"'); addHuffmanNode("00000000101", (char) 0x06); // non-print4 // depth 12 addHuffmanNode("000000000011", 'W'); addHuffmanNode("000000000100", 'X'); addHuffmanNode("000000000101", (char) 0x05); //non-print some shield code // depth 13 addHuffmanNode("0000000000100", '&'); addHuffmanNode("0000000000101", (char) 0x1f); //non-print2 // depth 14 addHuffmanNode("00000000000011", 'Q'); addHuffmanNode("00000000000100", 'Š'); addHuffmanNode("00000000000101", '\''); // mdr16 says 0x8a addHuffmanNode("00000000000110", 'Ë'); addHuffmanNode("00000000000111", '/'); // depth 15 addHuffmanNode("000000000000100", 'Æ'); addHuffmanNode("000000000000101", 'È'); // depth 16 addHuffmanNode("0000000000000101", (char) 0x04); // non-print3 addHuffmanNode("0000000000000110", '!'); addHuffmanNode("0000000000000111", (char) 0x9e); //Ž // depth 17 addHuffmanNode("00000000000000110",'+'); addHuffmanNode("00000000000000111", '–'); // different to minus mdr16: 0x96 addHuffmanNode("00000000000001000", 'Á'); //Á addHuffmanNode("00000000000001001", 'Ü'); // depth 18 addHuffmanNode("000000000000000110", '_'); addHuffmanNode("000000000000000111", '{'); addHuffmanNode("000000000000001000", '“'); // mdr16: 0x93 addHuffmanNode("000000000000001001", 'É'); addHuffmanNode("000000000000001010", 'Ð'); addHuffmanNode("000000000000001011", 'Ö'); // depth 19 addHuffmanNode("0000000000000000011", '?'); addHuffmanNode("0000000000000000100", '`'); // mdr16: 0x60 addHuffmanNode("0000000000000000101", '„'); // mdr16: 0x84 addHuffmanNode("0000000000000000110", 'ž'); // mdr16: 0x8e addHuffmanNode("0000000000000000111", '’'); // mdr16: 0x92 addHuffmanNode("0000000000000001000", 'Ä'); addHuffmanNode("0000000000000001001", 'Ø'); addHuffmanNode("0000000000000001010", 'Ú'); addHuffmanNode("0000000000000001011", 'Û'); // depth 20 addHuffmanNode("00000000000000000000", '#'); // offset into MDR 30/31? MapSource displays "HWY " addHuffmanNode("00000000000000000001", '%'); // addHuffmanNode("00000000000000000010", ':'); addHuffmanNode("00000000000000000011", ';'); addHuffmanNode("00000000000000000100", (char) 0x8f); addHuffmanNode("00000000000000000101", (char) 0xb8); Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Gerd Petermann <gpetermann_muenchen at hotmail.com> Gesendet: Montag, 20. Dezember 2021 10:59 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] [mkgmap-svn] Commit r572: MDR16 is some kind of codebook. Hi Ticker, OK, I see. It seems to work out for most of the delta values. Deltas are 6,9,6,4,3,2,5,2,3,3,1,4,9,4 I'll try to find out if I can modify the tree so that it matches all numbers. Probably sometimes I found too short codes. Good finding! Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap at jagit.co.uk> Gesendet: Montag, 20. Dezember 2021 10:38 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] [mkgmap-svn] Commit r572: MDR16 is some kind of codebook. Hi Gerd Are you OK with the idea of the letters at any level being to the right. Then the letters at this level take decreasing values. When exhausted, the next lower slot will be the start of the next level, so subtract 1 to find it and append '1' to the bit-string to get the starting position for the next level. in the test map there is, say: 000002cf | 000019 | 11 | struct level: 17 000002d0 | 00001a | 15 50 00 00 | struct for 17 000002d4 | 00001e | 10 | struct level: 16 000002d5 | 00001f | 19 80 00 00 | struct for 16 000002d9 | 000023 | 0f | struct level: 15 000002da | 000024 | 1c c0 00 00 | struct for 15 The differences between the first byte after the level indicator ie 15, 19 & 1c) give 4 and 3, which are the number of letters at level 17 and level 16 Ticker On Mon, 2021-12-20 at 09:18 +0000, Gerd Petermann wrote: > Hi Ticker, > please explain. What counters do you see? What do they mean? > > Gerd > > ________________________________________ > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von > Ticker Berkin <rwb-mkgmap at jagit.co.uk> > Gesendet: Montag, 20. Dezember 2021 09:49 > An: Development list for mkgmap > Betreff: Re: [mkgmap-dev] [mkgmap-svn] Commit r572: MDR16 > is some kind of codebook. > > Hi Gerd > > The tree is arranged so that letters at any level always have the > highest values, ie come in from the right, and there are no gaps so no > need for bit-flags. All it needs is the count of letters at each level > to determine the tree. > > For levels 7 to 18 this is consistent and the count can be determined > from the first byte in the "struct for {level}". > > Levels 19 and 20 are slightly out, but I think you found some > strangeness here, including something indicate using Mdr3x data. > > Level 6 count might be mixed into the following > > I haven't been able to work out levels 1-5 yet, but somewhere would > hope to find counts 0,0,1,7,9 maybe cumulative, maybe backwards, maybe > without the first 2 values, maybe starting from the cumulative level 6 > value. > > Ticker > > > On Sun, 2021-12-19 at 21:12 +0000, Gerd Petermann wrote: > > 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-bounces at lists.mkgmap.org.uk> im Auftrag > > von Ticker Berkin <rwb-mkgmap at 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 > > > > > > _______________________________________________ > > mkgmap-dev mailing list > > mkgmap-dev at lists.mkgmap.org.uk > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev > > _______________________________________________ > > mkgmap-dev mailing list > > mkgmap-dev at lists.mkgmap.org.uk > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev > > > _______________________________________________ > mkgmap-dev mailing list > mkgmap-dev at lists.mkgmap.org.uk > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev > _______________________________________________ > mkgmap-dev mailing list > mkgmap-dev at lists.mkgmap.org.uk > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev _______________________________________________ mkgmap-dev mailing list mkgmap-dev at lists.mkgmap.org.uk https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev _______________________________________________ mkgmap-dev mailing list mkgmap-dev at lists.mkgmap.org.uk https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev _______________________________________________ mkgmap-dev mailing list mkgmap-dev at lists.mkgmap.org.uk https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev -------------- next part -------------- A non-text attachment was scrubbed... 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