2/18/2014

02-18-14 - Understanding ANS - Conclusion

I think we can finally say that we understand ANS pretty well, so this series will end. I may cover some more ANS topics but they won't be "Understanding ANS".

Here is the index of all posts on this topic :

cbloom rants 1-30-14 - Understanding ANS - 1
cbloom rants 1-31-14 - Understanding ANS - 2
cbloom rants 02-01-14 - Understanding ANS - 3
cbloom rants 02-02-14 - Understanding ANS - 4
cbloom rants 02-03-14 - Understanding ANS - 5
cbloom rants 02-04-14 - Understanding ANS - 6
cbloom rants 02-05-14 - Understanding ANS - 7
cbloom rants 02-06-14 - Understanding ANS - 8
cbloom rants 02-10-14 - Understanding ANS - 9
cbloom rants 02-11-14 - Understanding ANS - 10
cbloom rants 02-14-14 - Understanding ANS - 11
cbloom rants 02-18-14 - Understanding ANS - 12

And here is some source code for my ANS implementation : (v2 02/21/2014)

ans_learning.cpp
ans_fast.cpp
ans.zip - contains ans_fast and ans_learning
cblib.zip is required to build my code

My home code is MSVC 2005/2008. Port if you like. Email me if you need help.

NOTE : this release is not a library you just download and use. It is intended as documentation of research. If you want some ANS code you can just use off the shelf, go get FiniteStateEntropy . You may also want ryg_rans .

I think I'll do a followup post with the performance of ans_fast and some optimization notes so it doesn't crud up this index post. Please put implementation speed discussion in that followup post .

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3 comments:

  1. CyanFebruary 18, 2014 at 4:01 PM

    I've tried to compile your project, but so far no luck. GCC complains about a missing crtdef.h, so I believe it means it must be compiled using MSVC.

    But MSVC has problem too. I'm using VS 2012 express. Here is the "debug" output ("release" is a lot more worse)

    1>------ Début de la génération : Projet : ans, Configuration : Debug x64 ------
    1> ans_fast.cpp
    1>C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\include\xtgmath.h(86): error C2244: 'cb::acos_asserting' : impossible de faire correspondre la définition de fonction avec une déclaration existante
    1> c:\my program files\dev\compression\entropy\bloom\ans\cblib/FloatUtil.h(964) : voir la déclaration de 'cb::acos_asserting'
    1>C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\include\xtgmath.h(87): error C2244: 'cb::asin_asserting' : impossible de faire correspondre la définition de fonction avec une déclaration existante
    1> c:\my program files\dev\compression\entropy\bloom\ans\cblib/FloatUtil.h(963) : voir la déclaration de 'cb::asin_asserting'
    1>C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\include\xtgmath.h(105): error C2244: 'cb::sqrt_asserting' : impossible de faire correspondre la définition de fonction avec une déclaration existante
    1> c:\my program files\dev\compression\entropy\bloom\ans\cblib/FloatUtil.h(962) : voir la déclaration de 'cb::sqrt_asserting'
    ========== Génération : 0 a réussi, 1 a échoué, 0 mis à jour, 0 a été ignoré ==========

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  2. CyanMarch 28, 2014 at 11:16 AM

    Is there any chance to have or build a "reduced dependency" version of fast ANS ?

    I'm trying to get your code included into an open source portable program, but the amount of dependency with cblib is quite deep (and afaik cblib is only for Windows).

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  3. cbloomMarch 28, 2014 at 2:41 PM

    I'd love to do nice open source versions of lots of stuff. (LZ-ANS anyone?) But I just don't have free time and noone is paying me to do it.

    I think it should be pretty easy though. I would just take the core functions and only port those. (you don't need string or fileenum)

    vector_s can be replaced with just a C array and a 'size' variable.

    cb::sum is trivial

    check_value_cast can be replaced with static_cast

    You have to use STL or write a heap.

    etc.

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