I think this matters a lot because output of our encoder will also be decoded by other zlib compliant decoders such as zlib.so itself. Or I had mis-read your question?
Пт, 12 сен 2014, Raul Miller написал(а): > If we define > > bitlen=:4 :0 > b=. 0~:x > b #inv #@>(b#x) hcodes b#y > ) > > Does it matter that these numbers are sometimes different from those > used in another implementation? > > Thanks, > > -- > Raul > > > On Fri, Sep 12, 2014 at 12:59 AM, bill lam <[email protected]> wrote: > > Consider an example > > > > 1 0 0 2 1 hcodes_jzlib_ i.5 > > +-----+-------+-------+-+---+ > > |1 1 1|1 1 0 0|1 1 0 1|0|1 0| > > +-----+-------+-------+-+---+ > > #&> 1 0 0 2 1 hcodes_jzlib_ i.5 > > 3 4 4 1 2 > > (0~:1 0 0 2 1)* #&> 1 0 0 2 1 hcodes_jzlib_ i.5 > > 3 0 0 1 2 > > > > classic huffman did not expect a 0 frequency and if there were > > it assigns the longest bit length to them. I think this is > > reasonable because it must have a non-zero bit length to encode > > an entity. For zlib, it seems that there is a third rule: > > For the bit length vector, bit lengths for zero frequency symbols > > are zero. > > > > From discussion here, I think using hcodes directly > > or indirectly for zlib is a wrong direction. > > > > Пт, 12 сен 2014, Raul Miller написал(а): > >> That's what I thought at first, also. > >> > >> But, let's look at the example at > >> http://www.jsoftware.com/pipermail/programming/2014-September/039299.html > >> > >> and the bit widths given at > >> http://www.jsoftware.com/pipermail/programming/2014-September/039327.html > >> > >> Here's how it looks to me: > >> > >> bits -:#@>F hcodes A > >> 0 > >> > >> Now.. is this a problem? > >> > >> I think it is. Consider: > >> > >> #0 -.~#@>F hcodes A > >> 286 > >> #0 -.~bits > >> 260 > >> > >> Incidentally, I found a bug in my code, while trying to understand and > >> express this concept. > >> > >> Fixed version here: > >> > >> bl_count=:3 :0 NB. y is result of freqs > >> 0,}.<:#/.~(,~ [: i. 1 + >./)y > >> ) > >> > >> start_vals=: +:@+/\.&.|.@}:@,~&0 > >> > >> find_codes=:3 :0 NB. y is result of freqs > >> b=. bl_count y > >> v=. start_vals b > >> n=. /:~ ~.y-.0 > >> o=. ;({./.~ /:~ (</. i.@#)) y-.0 > >> c=. ;<"1&.>n (([#2:) #: ])&.> (*b)#v+&.>i.&.>b > >> c /: o > >> ) > >> > >> An alternate version of the result from find_codes would be given by: > >> > >> def_code=:3 :0 > >> b=. bl_count y > >> v=. start_vals b > >> n=. /:~ ~.y-.0 > >> o=. ;({./.~ /:~ (</. i.@#)) y-.0 > >> c=. ;n,.&.>(*b)#v+&.>i.&.>b > >> (,. i.@#)c /: o > >> ) > >> > >> Thanks, > >> > >> -- > >> Raul > >> > >> > >> On Thu, Sep 11, 2014 at 8:33 PM, Joe Bogner <[email protected]> wrote: > >> > The bit widths are calculated from the huffman tree > >> > > >> > See > >> > > >> > http://stackoverflow.com/questions/759707/efficient-way-of-storing-huffman-tree > >> > > >> > http://www.siggraph.org/education/materials/HyperGraph/video/mpeg/mpegfaq/huffman_tutorial.html > >> > > >> > The timing is interesting considering we were talking about trees the > >> > other > >> > day: > >> > http://jsoftware.2058.n7.nabble.com/Ragged-Array-Shapes-are-Trees-td63207.html > >> > > >> > I was thinking to myself then how I hadn't used trees more than a few > >> > times > >> > in 18 years of programming. > >> > > >> > I am not sure how to apply your code to the problem. I also am not > >> > completely sure what problem we are solving. If it is creating a > >> > standalone J deflate implementation or PNG compression it may be a tall > >> > order. I would be curious why not just interface to a C library like what > >> > is done in the image3 addon: > >> > http://www.jsoftware.com/jwiki/Addons/media/image3 > >> > On Sep 11, 2014 6:27 PM, "Raul Miller" <[email protected]> wrote: > >> > > >> >> Here's the code I came up with, with Bill's help: > >> >> > >> >> bl_count=:3 :0 NB. y is result of freqs > >> >> 0,}.<:#/.~(,~ [: i. 1 + >./)y > >> >> ) > >> >> > >> >> start_vals=: +:@+/\.&.|.@}:@,~&0 > >> >> > >> >> find_codes=:3 :0 NB. y is result of freqs > >> >> b=. bl_count y > >> >> v=. start_vals b > >> >> n=. /:~ ~.y-.0 > >> >> o=. ;({./.~ /:~ (</. i.@#)) y > >> >> c=. ;<"1&.>n (([#2:) #: ])&.> (*b)#v+&.>i.&.>b > >> >> c /: o > >> >> ) > >> >> > >> >> An alternate version of the result from find_codes would be given by: > >> >> > >> >> def_code=:3 :0 > >> >> b=. bl_count y > >> >> v=. start_vals b > >> >> n=. /:~ ~.y-.0 > >> >> o=. ;({./.~ /:~ (</. i.@#)) y > >> >> c=. ;n,.&.>(*b)#v+&.>i.&.>b > >> >> (,. i.@#)c /: o > >> >> ) > >> >> > >> >> The argument to find_codes or def_code is the bit widths for each > >> >> symbol. > >> >> > >> >> I have not been able to figure out, from rfc 1951, how the bit widths > >> >> are calculated. > >> >> > >> >> Thanks, > >> >> > >> >> -- > >> >> Raul > >> >> > >> >> > >> >> > >> >> On Thu, Sep 11, 2014 at 4:47 PM, Joe Bogner <[email protected]> wrote: > >> >> > bill, I'd be interested in a solution but I don't think I can > >> >> > contribute any more on this. I played with > >> >> > https://code.google.com/p/miniz/ and became even more convinced of the > >> >> > complexity. It seems as though the compressor can decide whether to > >> >> > include the dictionary code table or not -- likely based on the size > >> >> > of the table. > >> >> > > >> >> > > >> >> > http://tools.ietf.org/html/rfc1950 > >> >> > > >> >> > A preset dictionary is specially useful to compress short input > >> >> > sequences. The compressor can take advantage of the dictionary > >> >> > context to encode the input in a more compact manner. > >> >> > > >> >> > > >> >> > More links for anyone who is following and cares to go down the rabbit > >> >> hole too: > >> >> > > >> >> > http://en.wikipedia.org/wiki/Canonical_Huffman_code > >> >> > > >> >> > > >> >> http://stackoverflow.com/questions/759707/efficient-way-of-storing-huffman-tree > >> >> > > >> >> > > >> >> > > >> >> > On Thu, Sep 11, 2014 at 1:28 PM, bill lam <[email protected]> wrote: > >> >> >> This codes seemed invalid. > >> >> >> > >> >> >> 1 is a prefix of 11 which is a prefix of 111. Suppose there > >> >> >> is a bit pattern of 1 1 , it is ambiguous to mean > >> >> >> [68,'1'] [68,'1'] > >> >> >> or [65,'11'] > >> >> >> > >> >> >> The huffman code in rfc is canonical meaning there is exactly one > >> >> >> possible huffman codes for a given bit length vector. This is > >> >> >> important because the huffman code table itself will not be > >> >> >> stored inside the deflate stream. The decoder only gets the bit > >> >> >> length vector, if encoder and decoder use different huffman code > >> >> >> for the same bit length vectors, it will not work. > >> >> >> > >> >> >> Чт, 11 сен 2014, Joe Bogner написал(а): > >> >> >>> Ignore the pako.js example output... It was just outputting the > >> >> >>> binary > >> >> >>> representation of A-Z, not the huffman code > >> >> >>> > >> >> >>> This is what I meant to send > >> >> >>> > >> >> >>> For ABCD: > >> >> >>> > >> >> >>> [65,'11'], > >> >> >>> [66,'0'], > >> >> >>> [67,'10'], > >> >> >>> [68,'1'], > >> >> >>> [256,'111'] > >> >> >>> > >> >> >>> It still doesn't seem to be sorting correctly lexographically, but > >> >> >>> I'm > >> >> >>> not really in my comfort zone of understanding: > >> >> >>> > >> >> >>> The RFC has this instead: > >> >> >>> > >> >> >>> Symbol Code > >> >> >>> ------ ---- > >> >> >>> A 10 > >> >> >>> B 0 > >> >> >>> C 110 > >> >> >>> D 111 > >> >> >>> > >> >> >>> I don't really know if it has to match the RFC or if each > >> >> >>> implementation is able to do its own thing as long since it includes > >> >> >>> the distance/reverse lookup table (whatever it's called). > >> >> >>> > >> >> >>> FYI > >> >> >>> > >> >> >>> > >> >> >>> This is where I inserted my code: > >> >> >>> > >> >> >>> /* > >> >> =========================================================================== > >> >> >>> * Generate the codes for a given tree and bit counts (which need > >> >> >>> not > >> >> be > >> >> >>> * optimal). > >> >> >>> * IN assertion: the array bl_count contains the bit length > >> >> >>> statistics > >> >> for > >> >> >>> * the given tree and the field len is set for all tree elements. > >> >> >>> * OUT assertion: the field code is set for all tree elements of non > >> >> >>> * zero code length. > >> >> >>> */ > >> >> >>> function gen_codes(tree, max_code, bl_count) > >> >> >>> // ct_data *tree; /* the tree to decorate */ > >> >> >>> // int max_code; /* largest code with non zero > >> >> frequency */ > >> >> >>> // ushf *bl_count; /* number of codes at each bit > >> >> >>> length > >> >> */ > >> >> >>> { > >> >> >>> var next_code = new Array(MAX_BITS+1); /* next code value for each > >> >> >>> bit length */ > >> >> >>> var code = 0; /* running code value */ > >> >> >>> var bits; /* bit index */ > >> >> >>> var n; /* code index */ > >> >> >>> > >> >> >>> /* The distribution counts are first used to generate the code > >> >> >>> values > >> >> >>> * without bit reversal. > >> >> >>> */ > >> >> >>> for (bits = 1; bits <= MAX_BITS; bits++) { > >> >> >>> next_code[bits] = code = (code + bl_count[bits-1]) << 1; > >> >> >>> } > >> >> >>> /* Check that the bit counts in bl_count are consistent. The last > >> >> code > >> >> >>> * must be all ones. > >> >> >>> */ > >> >> >>> //Assert (code + bl_count[MAX_BITS]-1 == (1<<MAX_BITS)-1, > >> >> >>> // "inconsistent bit counts"); > >> >> >>> //Tracev((stderr,"\ngen_codes: max_code %d ", max_code)); > >> >> >>> > >> >> >>> for (n = 0; n <= max_code; n++) { > >> >> >>> var len = tree[n*2 + 1]/*.Len*/; > >> >> >>> if (len === 0) { continue; } > >> >> >>> /* Now reverse the bits */ > >> >> >>> tree[n*2]/*.Code*/ = bi_reverse(next_code[len]++, len); > >> >> >>> > >> >> >>> if (tree!=static_ltree) { > >> >> >>> var v = tree[n*2]; > >> >> >>> console.log('[' + n + ",'" + v.toString(2) + "'],"); > >> >> >>> } > >> >> >>> //Tracecv(tree != static_ltree, (stderr,"\nn %3d %c l %2d c %4x > >> >> (%x) ", > >> >> >>> // n, (isgraph(n) ? n : ' '), len, tree[n].Code, > >> >> next_code[len]-1)); > >> >> >>> } > >> >> >>> > >> >> >>> } > >> >> >>> > >> >> >>> On Thu, Sep 11, 2014 at 11:55 AM, Joe Bogner <[email protected]> > >> >> wrote: > >> >> >>> > I think the prefix coding looks OK, but the 2 rules does not: > >> >> >>> > > >> >> >>> > I modified the code[1] to allow passing in a string and outputting > >> >> the codes > >> >> >>> > > >> >> >>> > C:\temp>deflate ABCDEFGHIJKLMONPQRSTUVWXYZ > >> >> >>> > code 65 : 0 00000000000000000000000000000000 > >> >> >>> > code 66 : 6 00000000000000000000000000000110 > >> >> >>> > code 67 : 8 00000000000000000000000000001000 > >> >> >>> > code 68 : 4 00000000000000000000000000000100 > >> >> >>> > code 69 : 22 00000000000000000000000000010110 > >> >> >>> > code 70 : 14 00000000000000000000000000001110 > >> >> >>> > code 71 : 30 00000000000000000000000000011110 > >> >> >>> > code 72 : 1 00000000000000000000000000000001 > >> >> >>> > code 73 : 17 00000000000000000000000000010001 > >> >> >>> > code 74 : 12 00000000000000000000000000001100 > >> >> >>> > code 75 : 9 00000000000000000000000000001001 > >> >> >>> > code 76 : 25 00000000000000000000000000011001 > >> >> >>> > code 77 : 5 00000000000000000000000000000101 > >> >> >>> > code 78 : 21 00000000000000000000000000010101 > >> >> >>> > code 79 : 13 00000000000000000000000000001101 > >> >> >>> > code 80 : 29 00000000000000000000000000011101 > >> >> >>> > code 81 : 3 00000000000000000000000000000011 > >> >> >>> > code 82 : 19 00000000000000000000000000010011 > >> >> >>> > code 83 : 11 00000000000000000000000000001011 > >> >> >>> > code 84 : 27 00000000000000000000000000011011 > >> >> >>> > code 85 : 7 00000000000000000000000000000111 > >> >> >>> > code 86 : 23 00000000000000000000000000010111 > >> >> >>> > code 87 : 15 00000000000000000000000000001111 > >> >> >>> > code 88 : 31 00000000000000000000000000011111 > >> >> >>> > code 89 : 2 00000000000000000000000000000010 > >> >> >>> > code 90 : 10 00000000000000000000000000001010 > >> >> >>> > > >> >> >>> > > >> >> >>> > I think it violates the consecutive rule... Each letter has the > >> >> >>> > same > >> >> >>> > frequency. ABCD have the same bit length. The order is off: > >> >> >>> > > >> >> >>> > If I sort it lexographically using javascript: > >> >> >>> > > >> >> >>> > JSON.stringify([['a','00000000000000000000000000000000'], > >> >> >>> > ['b','00000000000000000000000000000110'], > >> >> >>> > ['c','00000000000000000000000000001000'], > >> >> >>> > ['d','00000000000000000000000000000100']].sort(function(x,y) { > >> >> >>> > return > >> >> >>> > x[1] - y[1] })) > >> >> >>> > > >> >> >>> > > >> >> "[["a","00000000000000000000000000000000"],["d","00000000000000000000000000000100"],["b","00000000000000000000000000000110"],["c","00000000000000000000000000001000"]]" > >> >> >>> > > >> >> >>> > As you can see, the order comes out a,d,b,c > >> >> >>> > > >> >> >>> > I played around with a javascript implementation, pako[2]. It > >> >> >>> > seems > >> >> to > >> >> >>> > work correctly: > >> >> >>> > > >> >> >>> > As you can see, it sorts lexographically > >> >> >>> > > >> >> >>> > JSON.stringify([[65,'1000001'], > >> >> >>> > [66,'1000010'], > >> >> >>> > [67,'1000011'], > >> >> >>> > [68,'1000100'], > >> >> >>> > [69,'1000101'], > >> >> >>> > [70,'1000110'], > >> >> >>> > [71,'1000111'], > >> >> >>> > [72,'1001000'], > >> >> >>> > [73,'1001001'], > >> >> >>> > [74,'1001010'], > >> >> >>> > [75,'1001011'], > >> >> >>> > [76,'1001100'], > >> >> >>> > [77,'1001101'], > >> >> >>> > [78,'1001110'], > >> >> >>> > [79,'1001111'], > >> >> >>> > [80,'1010000'], > >> >> >>> > [81,'1010001'], > >> >> >>> > [82,'1010010'], > >> >> >>> > [83,'1010011'], > >> >> >>> > [84,'1010100'], > >> >> >>> > [85,'1010101'], > >> >> >>> > [86,'1010110'], > >> >> >>> > [87,'1010111'], > >> >> >>> > [88,'1011000'], > >> >> >>> > [89,'1011001'], > >> >> >>> > [90,'1011010']].sort(function(x,y) { return x[1] - y[1] })) > >> >> >>> > > >> >> >>> > > >> >> "[[65,"1000001"],[66,"1000010"],[67,"1000011"],[68,"1000100"],[69,"1000101"],[70,"1000110"],[71,"1000111"],[72,"1001000"],[73,"1001001"],[74,"1001010"],[75,"1001011"],[76,"1001100"],[77,"1001101"],[78,"1001110"],[79,"1001111"],[80,"1010000"],[81,"1010001"],[82,"1010010"],[83,"1010011"],[84,"1010100"],[85,"1010101"],[86,"1010110"],[87,"1010111"],[88,"1011000"],[89,"1011001"],[90,"1011010"]]" > >> >> >>> > > >> >> >>> > All the values are sorted correctly. > >> >> >>> > > >> >> >>> > Here it is with the same ABCD example: > >> >> >>> > > >> >> >>> > var pako = require('pako'); > >> >> >>> > var binaryString = pako.deflate('ABCD', { to: 'string' }); > >> >> >>> > console.log(binaryString); > >> >> >>> > var restored = pako.inflate(binaryString, { to: 'string' }); > >> >> >>> > console.log(restored); > >> >> >>> > > >> >> >>> > It successfully deflates and inflates itself > >> >> >>> > > >> >> >>> > x?♣A☺☺ ? mcÿ7♣A♫☻?☺♂ > >> >> >>> > ABCD > >> >> >>> > > >> >> >>> > > >> >> >>> > Hope this helps... > >> >> >>> > > >> >> >>> > [1] - > >> >> https://gist.github.com/joebo/a3c2932f0e5a7a0c3f07#file-deflate-c-L2613 > >> >> >>> > [2] - https://rawgit.com/nodeca/pako/master/dist/pako.js > >> >> >>> > > >> >> >>> > On Thu, Sep 11, 2014 at 11:33 AM, bill lam <[email protected]> > >> >> wrote: > >> >> >>> >> This is strange since every author must had decode its own > >> >> >>> >> encoded > >> >> >>> >> data as a smoke test. > >> >> >>> >> > >> >> >>> >> Did you test if huffman code or bit lengths it produced was > >> >> >>> >> correct or not, ie it is a prefix coding and it satisfy the 2 > >> >> >>> >> rules in rfc. > >> >> >>> >> > >> >> >>> >> Чт, 11 сен 2014, Joe Bogner написал(а): > >> >> >>> >>> unfortunately the dynamic coding in the putty fork doesn't seem > >> >> >>> >>> to > >> >> work: > >> >> >>> >>> > >> >> >>> >>> deflate -c deflate.c > out > >> >> >>> >>> deflate -d out > >> >> >>> >>> > >> >> >>> >>> decoding error: incorrect data checksum > >> >> >>> >>> > >> >> >>> >>> > >> >> >>> >>> it works fine with static tables > >> >> >>> >>> > >> >> >>> >>> C:\temp>echo ABCD > ABCD > >> >> >>> >>> > >> >> >>> >>> C:\temp>deflate -c ABCD > out > >> >> >>> >>> > >> >> >>> >>> C:\temp>deflate -d out > >> >> >>> >>> ABCD > >> >> >>> >>> > >> >> >>> >>> I added some debugging code to determine that deflating > >> >> >>> >>> deflate.c > >> >> >>> >>> would be a dynamic table... Assuming it's broke, I probably > >> >> wouldn't > >> >> >>> >>> use it as a reference implementation after all > >> >> >>> >>> > >> >> >>> >>> On Thu, Sep 11, 2014 at 3:45 AM, bill lam <[email protected]> > >> >> wrote: > >> >> >>> >>> > the frequencies (guessing from bit lengths) should be > >> >> >>> >>> > something > >> >> like 2 3 1 1 > >> >> >>> >>> > (2 3 1 1) hcodes 'ABCD' > >> >> >>> >>> > > >> >> >>> >>> > the hard part is the inverse problem: how to get the huffman > >> >> code with > >> >> >>> >>> > prior knowing the bits for each symbol. Your pointer to the > >> >> putty > >> >> >>> >>> > fork looks like helpful. The comment is in lines 861 to 914, > >> >> the code > >> >> >>> >>> > itself in line 915 to 964. Do you know how to express it in J? > >> >> >>> >>> > Thanks. > >> >> >>> >>> > > >> >> >>> >>> > On Thu, Sep 11, 2014 at 2:57 PM, Joe Bogner > >> >> >>> >>> > <[email protected]> > >> >> wrote: > >> >> >>> >>> >> Here a few other links ... after reading through the RFC. Not > >> >> sure if > >> >> >>> >>> >> they help, but just sharing from my own research into > >> >> >>> >>> >> assisting > >> >> on > >> >> >>> >>> >> this topic > >> >> >>> >>> >> > >> >> >>> >>> >> https://github.com/evegard/pngview/blob/master/huffman.c#L54 > >> >> >>> >>> >> > >> >> >>> >>> >> And a fork of the putty version with dynamic huffman coding: > >> >> >>> >>> >> > >> >> http://rc.quest.com/viewvc/putty/trunk/halibut/deflate.c?diff_format=s&revision=2&view=markup > >> >> >>> >>> >> > >> >> >>> >>> >> Or just generally googling some of the code from the RFC: > >> >> >>> >>> >> > >> >> https://www.google.com/search?q=next_code%5Blen%5D%2B%2B%3B&oq=next_code%5Blen%5D%2B%2B%3B&aqs=chrome..69i57.387j0j7&sourceid=chrome&es_sm=93&ie=UTF-8#q=next_code%5Blen%5D%2B%2B%3B&start=20 > >> >> >>> >>> >> > >> >> >>> >>> >> > >> >> >>> >>> >> Using the code from > >> >> >>> >>> >> http://www.jsoftware.com/jwiki/Essays/Huffman%20Coding, I got > >> >> stuck > >> >> >>> >>> >> trying to match a simple example to the binary tree in the > >> >> >>> >>> >> RFC: > >> >> >>> >>> >> > >> >> >>> >>> >> From the RFC: > >> >> >>> >>> >> > >> >> >>> >>> >> /\ Symbol Code > >> >> >>> >>> >> 0 1 ------ ---- > >> >> >>> >>> >> / \ A 00 > >> >> >>> >>> >> /\ B B 1 > >> >> >>> >>> >> 0 1 C 011 > >> >> >>> >>> >> / \ D 010 > >> >> >>> >>> >> A /\ > >> >> >>> >>> >> 0 1 > >> >> >>> >>> >> / \ > >> >> >>> >>> >> D C > >> >> >>> >>> >> > >> >> >>> >>> >> > >> >> >>> >>> >> > >> >> >>> >>> >> (4#1) hcodes 'ABCD' > >> >> >>> >>> >> ┌───┬───┬───┬───┐ > >> >> >>> >>> >> │0 0│0 1│1 0│1 1│ > >> >> >>> >>> >> └───┴───┴───┴───┘ > >> >> >>> >>> >> > >> >> >>> >>> >> Per the RFC, ideally that should match this? > >> >> '00';'1';'011';'010' > >> >> >>> >>> >> > >> >> >>> >>> >> > >> >> >>> >>> >> From there, it seems like a pretty straightforward exercise > >> >> >>> >>> >> to > >> >> >>> >>> >> transliterate the C code from the RFC into J code to recode > >> >> >>> >>> >> the > >> >> >>> >>> >> example to: > >> >> >>> >>> >> > >> >> >>> >>> >> > >> >> >>> >>> >> Symbol Code > >> >> >>> >>> >> ------ ---- > >> >> >>> >>> >> A 10 > >> >> >>> >>> >> B 0 > >> >> >>> >>> >> C 110 > >> >> >>> >>> >> D 111 > >> >> >>> >>> >> > >> >> >>> >>> >> > >> >> >>> >>> >> I would probably start with a looping construct like what's > >> >> >>> >>> >> in > >> >> the RFC > >> >> >>> >>> >> and then figure out a more J way to do it, but first I would > >> >> need to > >> >> >>> >>> >> figure out how to create the binary tree in that initial > >> >> >>> >>> >> format. > >> >> >>> >>> >> > >> >> >>> >>> >> On Wed, Sep 10, 2014 at 7:41 PM, bill lam > >> >> >>> >>> >> <[email protected]> > >> >> wrote: > >> >> >>> >>> >>> Thanks Joe, > >> >> >>> >>> >>> putty only use zlib static huffman for encoding so that it > >> >> does not build > >> >> >>> >>> >>> any huffman dictionary table. > >> >> >>> >>> >>> > >> >> >>> >>> >>> The zlib static huffman code does not care about individual > >> >> symbol's > >> >> >>> >>> >>> frequency, it just encode 0 to 286 into bits, see section > >> >> 3.2.6. > >> >> >>> >>> >>> On Sep 11, 2014 1:26 AM, "Joe Bogner" <[email protected]> > >> >> wrote: > >> >> >>> >>> >>> > >> >> >>> >>> >>>> You've already likely considered this, but if it were me I > >> >> would compare > >> >> >>> >>> >>>> results to a working implementation. The one from putty > >> >> >>> >>> >>>> seems > >> >> pretty clean > >> >> >>> >>> >>>> and standalone: > >> >> >>> >>> >>>> > >> >> https://raw.githubusercontent.com/grumpydev/PortablePuTTY/master/SSHZLIB.C > >> >> >>> >>> >>>> . I was able to compile it on windows no problem and I > >> >> >>> >>> >>>> assume > >> >> it'd be fine > >> >> >>> >>> >>>> on linux as well. > >> >> >>> >>> >>>> > >> >> >>> >>> >>>> On Wed, Sep 10, 2014 at 1:00 PM, Raul Miller < > >> >> [email protected]> > >> >> >>> >>> >>>> wrote: > >> >> >>> >>> >>>> > >> >> >>> >>> >>>> > I think the use of the term "consecutive" rather than > >> >> "sequential" is > >> >> >>> >>> >>>> > telling. > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > The described algorithm is: compute the huffman code > >> >> lengths: > >> >> >>> >>> >>>> > #@>F1 hcodes A1 > >> >> >>> >>> >>>> > 1 3 7 7 6 6 6 6 6 6 6 2 > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > Then assign ascending huffman codes first in length order > >> >> and then > >> >> >>> >>> >>>> > within codes of the same length. > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > Taken literally, that might be something like this: > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > H=: 4 :0 > >> >> >>> >>> >>>> > L=.#@> x hcodes y > >> >> >>> >>> >>>> > U=.~.L > >> >> >>> >>> >>>> > ;<@(({.{.U e.~i.&.<:@{.)<@:+"1-@{.{."1 #:@i.@#)/.~L > >> >> >>> >>> >>>> > ) > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > ":@>F1 H A1 > >> >> >>> >>> >>>> > 0 > >> >> >>> >>> >>>> > 1 1 0 > >> >> >>> >>> >>>> > 1 1 1 0 0 1 0 > >> >> >>> >>> >>>> > 1 1 1 0 0 1 1 > >> >> >>> >>> >>>> > 1 1 1 0 0 0 > >> >> >>> >>> >>>> > 1 1 1 0 0 1 > >> >> >>> >>> >>>> > 1 1 1 0 1 0 > >> >> >>> >>> >>>> > 1 1 1 0 1 1 > >> >> >>> >>> >>>> > 1 1 1 1 0 0 > >> >> >>> >>> >>>> > 1 1 1 1 0 1 > >> >> >>> >>> >>>> > 1 1 1 1 1 0 > >> >> >>> >>> >>>> > 1 0 > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > But is this correct? Is it actually safe to leave the > >> >> results like > >> >> >>> >>> >>>> > this - with all codes of the same length being > >> >> >>> >>> >>>> > consecutive > >> >> to each > >> >> >>> >>> >>>> > other? > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > F (hcodes -:&:(#@>) H) A > >> >> >>> >>> >>>> > 0 > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > No. > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > So... "consecutive" must refer only to the values used > >> >> >>> >>> >>>> > and > >> >> not their > >> >> >>> >>> >>>> > order within the result. > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > Perhaps something like this: > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > deflatecodes=:4 :0 > >> >> >>> >>> >>>> > L=.#@> x hcodes y > >> >> >>> >>> >>>> > U=.~.L > >> >> >>> >>> >>>> > R=. ;<@(({.{.U e.~i.&.<:@{.)<@:+"1-@{.{."1 #:@i.@#)/.~L > >> >> >>> >>> >>>> > R/:;(</. i.@#)L > >> >> >>> >>> >>>> > ) > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > F (hcodes -:&:(#@>) deflatecodes) A > >> >> >>> >>> >>>> > 1 > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > There should be a better way of doing this, but this > >> >> >>> >>> >>>> > should > >> >> at least > >> >> >>> >>> >>>> > get you started. > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > Thanks, > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > -- > >> >> >>> >>> >>>> > Raul > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > On Wed, Sep 10, 2014 at 10:45 AM, bill lam < > >> >> [email protected]> wrote: > >> >> >>> >>> >>>> > > For huffman coding used in zlib: > >> >> >>> >>> >>>> > > https://www.ietf.org/rfc/rfc1951.txt section 3.2.2. > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > The Huffman codes used for each alphabet in the > >> >> >>> >>> >>>> > > "deflate" > >> >> >>> >>> >>>> > > format have two additional rules: > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > * All codes of a given bit length have > >> >> >>> >>> >>>> > > lexicographically > >> >> >>> >>> >>>> > > consecutive values, in the same order as the symbols > >> >> >>> >>> >>>> > > they represent; > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > * Shorter codes lexicographically precede longer > >> >> >>> >>> >>>> > > codes. > >> >> >>> >>> >>>> > > I tried jwiki hcodes in > >> >> >>> >>> >>>> > > I try Roger's essay > >> >> >>> >>> >>>> > > http://www.jsoftware.com/jwiki/Essays/Huffman%20Coding > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > hc=: 4 : 0 > >> >> >>> >>> >>>> > > if. 1=#x do. y > >> >> >>> >>> >>>> > > else. ((i{x),+/j{x) hc (i{y),<j{y [ i=. (i.#x) -. j=. > >> >> 2{./:x end. > >> >> >>> >>> >>>> > > ) > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > hcodes=: 4 : 0 > >> >> >>> >>> >>>> > > assert. x -:&$ y NB. weights and words have > >> >> same shape > >> >> >>> >>> >>>> > > assert. (0<:x) *. 1=#$x NB. weights are non-negative > >> >> >>> >>> >>>> > > assert. 1 >: L.y NB. words are boxed not more > >> >> than once > >> >> >>> >>> >>>> > > w=. ,&.> y NB. standardized words > >> >> >>> >>> >>>> > > assert. w -: ~.w NB. words are unique > >> >> >>> >>> >>>> > > t=. 0 {:: x hc w NB. minimal weight binary > >> >> >>> >>> >>>> > > tree > >> >> >>> >>> >>>> > > ((< S: 0 t) i. w) { <@(1&=)@; S: 1 {:: t > >> >> >>> >>> >>>> > > ) > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > but the coding produced is malformed for zlib. eg, > >> >> >>> >>> >>>> > > this is what I ran into trouble > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > f1=: 1 256 17 1 1 9 1 > >> >> >>> >>> >>>> > > f2=: 2 1 0 1 255 0 1536 > >> >> >>> >>> >>>> > > F=: ,/(f1#f2) > >> >> >>> >>> >>>> > > A=: i.286 > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > F hcodes A > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > Or a shorter example > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > A1=: i.12 > >> >> >>> >>> >>>> > > F1=: 2 1 0 0 0 0 0 0 0 0 0 1 > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > F1 hcodes A1 > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > Any idea? > >> >> >>> >>> >>>> > > > >> >> >>> >>> >>>> > > -- > >> >> >>> >>> >>>> > > regards, > >> >> >>> >>> >>>> > > ==================================================== > >> >> >>> >>> >>>> > > GPG key 1024D/4434BAB3 2008-08-24 > >> >> >>> >>> >>>> > > gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3 > >> >> >>> >>> >>>> > > gpg --keyserver subkeys.pgp.net --armor --export > >> >> >>> >>> >>>> > > 4434BAB3 > >> >> >>> >>> >>>> > > > >> >> ---------------------------------------------------------------------- > >> >> >>> >>> >>>> > > For information about J forums see > >> >> http://www.jsoftware.com/forums.htm > >> >> >>> >>> >>>> > > >> >> ---------------------------------------------------------------------- > >> >> >>> >>> >>>> > For information about J forums see > >> >> http://www.jsoftware.com/forums.htm > >> >> >>> >>> >>>> > > >> >> >>> >>> >>>> > >> >> ---------------------------------------------------------------------- > >> >> >>> >>> >>>> For information about J forums see > >> >> http://www.jsoftware.com/forums.htm > >> >> >>> >>> >>>> > >> >> >>> >>> >>> > >> >> ---------------------------------------------------------------------- > >> >> >>> >>> >>> For information about J forums see > >> >> http://www.jsoftware.com/forums.htm > >> >> >>> >>> >> > >> >> ---------------------------------------------------------------------- > >> >> >>> >>> >> For information about J forums see > >> >> http://www.jsoftware.com/forums.htm > >> >> >>> >>> > > >> >> ---------------------------------------------------------------------- > >> >> >>> >>> > For information about J forums see > >> >> http://www.jsoftware.com/forums.htm > >> >> >>> >>> > >> >> ---------------------------------------------------------------------- > >> >> >>> >>> For information about J forums see > >> >> http://www.jsoftware.com/forums.htm > >> >> >>> >> > >> >> >>> >> -- > >> >> >>> >> regards, > >> >> >>> >> ==================================================== > >> >> >>> >> GPG key 1024D/4434BAB3 2008-08-24 > >> >> >>> >> gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3 > >> >> >>> >> gpg --keyserver subkeys.pgp.net --armor --export 4434BAB3 > >> >> >>> >> > >> >> ---------------------------------------------------------------------- > >> >> >>> >> For information about J forums see > >> >> http://www.jsoftware.com/forums.htm > >> >> >>> ---------------------------------------------------------------------- > >> >> >>> For information about J forums see > >> >> >>> http://www.jsoftware.com/forums.htm > >> >> >> > >> >> >> -- > >> >> >> regards, > >> >> >> ==================================================== > >> >> >> GPG key 1024D/4434BAB3 2008-08-24 > >> >> >> gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3 > >> >> >> gpg --keyserver subkeys.pgp.net --armor --export 4434BAB3 > >> >> >> ---------------------------------------------------------------------- > >> >> >> For information about J forums see > >> >> >> http://www.jsoftware.com/forums.htm > >> >> > ---------------------------------------------------------------------- > >> >> > For information about J forums see http://www.jsoftware.com/forums.htm > >> >> ---------------------------------------------------------------------- > >> >> For information about J forums see http://www.jsoftware.com/forums.htm > >> > ---------------------------------------------------------------------- > >> > For information about J forums see http://www.jsoftware.com/forums.htm > >> ---------------------------------------------------------------------- > >> For information about J forums see http://www.jsoftware.com/forums.htm > > > > -- > > regards, > > ==================================================== > > GPG key 1024D/4434BAB3 2008-08-24 > > gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3 > > gpg --keyserver subkeys.pgp.net --armor --export 4434BAB3 > > ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm -- regards, ==================================================== GPG key 1024D/4434BAB3 2008-08-24 gpg --keyserver subkeys.pgp.net --recv-keys 4434BAB3 gpg --keyserver subkeys.pgp.net --armor --export 4434BAB3 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
