SmallapackPortingOnSqueak

Introduction

Porting the first version of Smallapack on Squeak (in 2006) has not been that easy. Here are a few historical notes taken while porting.

Details

Problems encountered porting Smallapack on Squeak:

first problem: (minor) line end conventions in file.

• I develop under linux where line end convention is LF.
• I found Squeak very tyrannic with its Mac CR convention...
• All my attempts to work around failed and i had to resolve myself converting my files to CR before going to Squeak...

second problem: lack of FFI examples

• How to pass an array of structures? (the Complex Matrix case)
• How to load a library before another? (mostly in Unix environment)
• How to define a specific library path?

All these questions were resolved slowly...

I proposed a new feature to automagically free allocated memory at http://bugs.squeak.org/view.php?id=3692
I did not invent much, this kind of utility exists in VW for a long time.

I also experimented an infinite loop as described at http://bugs.squeak.org/view.php?id=3691

third problem: method can only have 15 arguments

LAPACK have some functions with more than 15...
I circumvent this problem using a trick: pass a single array of arguments.
I implemented Compiler tweak for having this automated (and not crafted by hand...)
This can be found at http://bugs.squeak.org/view.php?id=2918

fourth problem: a strange bug in unix FFI

This bug is described at http://bugs.squeak.org/view.php?id=3929
I remained stuck a long time by this one...
It prevented my SUnit TestCase to work.
I finally solved it and the patch is integrated in Squeak VM. Anyway, Eliot Miranda has totally cleaned FFI on the cog vm

fifth problem: understand Squeak tools Monticello, SqueakMap, ...

Not really a problem, i find Monticello is great.
But as a Newbie, there's always a learning curve...

sixth problem: no Callback framework

I need such framework for example in Schur algorithm (a function for sorting eigenvalues is necessary)
update: it seems now possible with Aliens, but not yet implemented in Smallapack

seventh problem: bugs in Number library

Especially, with floating point arithmetic...
To be fair, most of these bugs are found in major Smalltalk implementations (VW, Squeak, Dolphin, ST/X, gst, ...)
But Squeak had a little bit more bugs than others...
You can see some of my patches at:
http://bugs.squeak.org/view.php?id=3564 , 3568 , 3512 , 3360 , 3504 , 3493 , 3374 , 3373 , 2688 , 3133

What i like in Squeak:

• FFI is somehow more simple than VW DLLCC.
  
• The ability to work in Smalltalk memory with ByteArray is also simpler than allocating/freeing external heap.
  
• Squeak community is great.
  
• Monticello
  
• Mantis bug database

All in all, porting to Squeak was a very interesting experience!