[Mesa-dev] [GSoC2016] Interested in implementing "Soft" double precision floating point support

[Marek Olšák]

On Thu, Mar 10, 2016 at 3:30 PM, tournier.elie <tournier.elie at gmail.com> wrote:
> First, thank you all for your answers.
>
> So if I summarize what was said, we need
> Ian:
>  - add
>  - negate
>  - absolute value
>  - multiply
>  - reciprocal
>  - convert to single precision
>  - convert from single precision
> Roland:
>  - sqrt
>  - comparaison (< / == / >)
>  - floor/ceil
> I will contact Pat Brown (His name appear in the contact field in [1]) to
> know if we need the function below for implement gpu_shader_fp64.
>  - pow
>  - exp
>  - log
>
> About the license
>
> Like I mentioned in the project description, there are quite a few
> existing C implementations of these functions.  Finding one of those
> that you can understand and that has a compatible license is probably
> the best place to start.
>
> Main Mesa code is under MIT license.
> If I chose to use a GNU GPL license file like Linux kernel [3], my code must
> be under GNU GPL and probably all the project too. Am I right?
>
> [1] https://www.opengl.org/registry/specs/ARB/gpu_shader_fp64.txt
> [2] http://www.mesa3d.org/license.html
> [3]
> https://github.com/torvalds/linux/blob/097f70b3c4d84ffccca15195bdfde3a37c0a7c0f/arch/arm/nwfpe/softfloat.c

You can't use GNU GPL for this project.

The kernel as a whole is licensed under GNU GPL, but some source files
aren't. The file you linked doesn't mention GNU GPL. Somebody needs to
verify that the file you linked can be legally re-licensed under the
MIT license. If not, I think you have to forget the contents of the
file immediately, but I'm not a lawyer.

Marek