Oops, I should have included example uses. umix is a dyad - you need to give it a left argument saying how many times you want it to run.
Try: 1 umix i.8 emix would need another loop (or a power conjunction) to achieve the same thing. Thanks, -- Raul On Sat, Sep 5, 2015 at 7:00 PM, Jose Mario Quintana <[email protected]> wrote: > emix i.8 > 68112070 67580715 540296643 2058 539239185 529307 67580712 539769534 > > umix i.8 > |length error: SH > | umix i.8 > |[-23] > > ? > > > On Sat, Sep 5, 2015 at 10:50 AM, Raul Miller <[email protected]> wrote: > >> Nice. >> >> Except, I prefer shift to take the number of bits as a left argument. >> Also, there's still the matter of doing it tacitly. >> >> So, here's my rephrasing of your excellent work, for the explicit mix: >> >> top=: <:2^32 >> SH =: top AND 34 b. NB. 32 bit shift >> MP =: top AND + NB. 32 bit addition ("modplus") >> >> emix =: verb define >> for_j. 11 _2 8 _16 10 _4 8 _9 do. >> 'a b c d e f g h' =. y >> i=. a XOR j SH b >> y =. (b MP c), c, (d MP i), e, f, g, h, i >> end. >> ) >> >> And, here is a tacit equivalent: >> >> rfold=: 1 :'u&.>/@,&.:(<"_1),:' >> tmix=: _9 8 _4 10 _16 8 _2 11 umix rfold ] >> imix=: 1 }. ], (0,[) XOR/@SH 2 {. ] >> ymix=: MP/ .*&(8 8$1(8 58}),=i.8) >> umix=: ymix@imix >> >> Honestly, though, I prefer the explicit version. It's simpler, more >> concise, and faster. But I think that that is more a direct >> consequence of the (somewhat arbitrary) design of the algorithm than >> anything else. >> >> Thanks, >> >> -- >> Raul >> >> On Sat, Sep 5, 2015 at 12:33 AM, Michal Wallace >> <[email protected]> wrote: >> > It's just a hashing algorithm, mixing up the bits of data in a >> > deterministic but irreversible way. >> > >> > If you notice that the "alphabet-distance" between the variable names on >> > each line is always the same, >> > my implementation might make more sense. Since the offsets are always the >> > same, I'm just rotating the >> > array and re-applying the same logic. >> > >> > Here's the c code that will tell us what the result should be for mix >> i.8: >> > >> > #include <stdio.h> >> > int main() { >> > int a,b,c,d,e,f,g,h; >> > a=0;b=1;c=2;d=3;e=4;f=5;g=6;h=7; >> > a^=b<<11; d+=a; b+=c; >> > b^=c>>2; e+=b; c+=d; >> > c^=d<<8; f+=c; d+=e; >> > d^=e>>16; g+=d; e+=f; >> > e^=f<<10; h+=e; f+=g; >> > f^=g>>4; a+=f; g+=h; >> > g^=h<<8; b+=g; h+=a; >> > h^=a>>9; c+=h; a+=b; >> > // a b c d e f g h >> > printf("%d %d %d %d %d %d %d %d\n", a,b,c,d,e,f,g,h); >> > } >> > >> > Answer: >> > >> > 68112070 67580715 540296643 2058 539239185 529307 67580712 539769534 >> > >> > Here's the corrected code: >> > >> > top=: <:2^32 >> > >> > SH =: top AND (34 b.)~ NB. 32 bit shift >> > >> > MP =: top AND + NB. 32 bit addition ("modplus") >> > >> > mix =: verb define >> > >> > for_i. 11 _2 8 _16 10 _4 8 _9 do. >> > >> > 'a b c d e f g h' =. y >> > >> > x =. a XOR b SH i >> > >> > y =. 1 |. x, (b MP c), c, (d MP x), e, f, g, h >> > >> > end. >> > >> > ) >> > >> > >> > assert (mix i.8) -: 68112070 67580715 540296643 2058 539239185 529307 >> > 67580712 539769534 >> > >> > >> > >> > >> > >> > >> > >> > On Fri, Sep 4, 2015 at 10:34 PM, Dan Bron <[email protected]> wrote: >> > >> >> Michal Wallace wrote: >> >> > I don't know whether or not this produces the correct results because >> I >> >> > don't have any test data, but... >> >> >> >> >> >> Yeah, that is troublesome. Unfortunately, it’s the same catch-22 I’m >> in. >> >> >> >> I’m transliterating the C code here: >> >> >> >> http://rosettacode.org/wiki/The_ISAAC_Cipher#C < >> >> http://rosettacode.org/wiki/The_ISAAC_Cipher#C> >> >> >> >> as directly as possible into J, so that I can get a working program >> which >> >> produces the expected outputs for the given inputs. >> >> >> >> Once I have a working program that I can test, interrogate, and reason >> >> about, I’ll be in a much better position to refactor the code into >> >> idiomatic, and, hopefully, elegant J. >> >> >> >> But the very reason I have to do it this cart-before-horse way is >> because >> >> I don’t (yet) understand the algorithm on a conceptual level. So I’m >> >> starting from the code. >> >> >> >> I guess what I was asking for in my previous email was for someone who >> >> does or can easily grok the concepts underlying the code to express >> them in >> >> J (which is a language I speak, so such code would teach me those >> concepts). >> >> >> >> Barring that, someone who is confident enough in his C to trust in his >> >> translation of the macro would also suffice. >> >> >> >> (One big obstacle here, and I think more broadly to the lack of adoption >> >> of ISAAC the author of that article laments is the majority of >> >> easily-accessible artifacts dealing with it are code, rather than >> prose.) >> >> >> >> -Dan >> >> ---------------------------------------------------------------------- >> >> 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
