[Gegl-developer] Question about the use of C99/gcc built-in math intrinsics within GEGL on gfloats

[Sven Neumann]

Hi,

On Fri, 2008-09-12 at 12:50 -0400, Nicolas Robidoux wrote:
> --------
> CONTEXT:
> --------
> 
> I have completely changed the gegl/buffer/gegl-sampler-yafr.c
> code.
> 
> Before I put together the patch to the new yafr, I would like to
> see if I could make the code even faster by using C99/gcc
> built-in math intrinsics. I have not tried this yet.

It would be interesting to know if this makes a difference and how much
of a difference it makes. In general it seems like a dependency on GCC
is a high price to pay and I am not sure if we are willing to do that.
Depending on C99 is something that could certainly be considered.

> I noticed that fabs, fmin and copysign, or similar C99/gcc
> built-ins, are not found anywhere in the gegl source.
> 
> Is there a preferred/tolerated way of using such math functions in gegl?

As far as I can see there is no decision on this yet.

> Can I assume that gfloats are floats?

Yes.

> Can I assume that gdoubles are doubles?

Yes.

> Must I program with the possibility that gfloats be doubles?

No, gfloat is just a typedef to float. Always.

> Must I program with the possibility that gdoubles be floats?

No, gdouble is just a typedef to double. Always.


Sven