On Wed, Feb 8, 2012 at 9:56 AM, Olе Streicher
<[log in to unmask]> wrote:
> Tim Jenness <[log in to unmask]> writes:
>> I actually want all the software to be GPL and especially AST. The
>> whole point of this discussion is to work out how we get this done. I
>> don't think anyone is objecting to the concept of making AST compliant
>> I'm just wondering how it's going to be possible in the short term.
>
> Since the problem is slalib, I see basically four ways:
>
> 1. Use the Fortran library and live with the poorer performance. Or try
> to convince the compiler allocate local variables on the stack
> ("-frecursive"?). This is the fastest solution.
>
Using a compiler flag is not a portable solution. You would have to
package up CNF to be portable. It may be that you could also have two
binary versions of AST. One with threads enabled that is crippled with
the mutex and one without threads. For all I know DS9 doesn't need the
thread-safe version.
> 2. Convince Patrick to release the C version of his library under GPL.
> This would be the ideal solution.
That's highly unlikely. The only possible way would be for the subset
used by AST to be included in AST but also rebranded to make it
obvious that it's not the official SLA.
>
> 3. Convert the Fortran library to C, using f.e. f2c This is basically
> not too complicated, and after some automated polishing one could get
> beautiful, readable C source code with only small human intervention.
> Since the Fortran version is GPL, a conversion to C would count as
> "derived work" and could be also released under that license.
> In the C code, one has the full control over "static" vs. "auto"
> local variables -- f2c even has the option "-a" to do this.
> This requires some work, but is at the end as good as 2.
>
f2c must have made many improvements since last time I used it. Last
time I tried it I ended up with something that worked but may as well
have been called obfuscated C. Also ended up with a dependency against
the f2c library which was never a good idea (I think that might only
come into play if fortran I/O is involved).
> 4. Clarify the GPL compability of SOFA and switch over to it.
>
I had forgotten about the problem of shipping AST with a subset of
SOFA being incompatible with the GPL. Presumably SOFA's licence
doesn't prevent GPL code from linking against SOFA.
--
Tim Jenness
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