ARMv7 Architecture support for NuPIC

[akamlani]

Moving up to a recent codebase for ARMv7 Architecture support to get mainlined. Platform: Samsung Chromebook Ubuntu (Crouton).

Few Open Issues for Discussion:

• Currently we are combining platform os and architecture specifics in ../external//. Based on the current model, adding armv7 support would mean I would have to add something like "linux32armv7" and have the architecture and configuration files change to use this folder and that add the preprocessor macros in the code where we are currently using for "NTA_platform_linux32arm". Is this acceptable? Technically this should be combined in "linux32arm" and have a separate armv6 and armv7 folders within for the proper cpu architecture. But this should probably be handled as a separate issue.
• I am using the following sources to compile for ARMv7 platform, are there additional dependencies on top of these? As I came across the below mentioned pull requests, which seem to dictate NuPIC has additional changes on top of these downloads. (1) http://code.google.com/p/yaml-cpp/ (version 0.3.0) Came across the following: https://github.com/numenta/nupic/pull/301 (2) http://www.zlib.net/ (version 1.2.8) (3) http://apr.apache.org (apr: version 1.4.8, apr-util: 1.5.2) Came across the following: https://github.com/numenta/nupic/pull/253 (4) http://www.swig.org/ (2.0.10) Came across the following: https://github.com/numenta/nupic/pull/344

However still facing build errors. Thought I would check first on dependencies before pasting build error logs. Comments?

[breznak]

Hi, cool to see the Chromebook knowcking on the door!

I think for now you can go with linux32arm7 separate, though it'd be nice to have them merged under linux32arm in future, like you say.

To the dependencies, we do not patch any of those, but specific build flags are sometimes used to work with NuPIC, that's why we ship these libs statically. So basically you should use the istructions (if applicable) in the PRs you mentioned and rebuild for the new platform..

[akamlani]

Submitted PR 418: https://github.com/numenta/nupic/pull/418