[Pixman] [PATCH 06/15] pixman-filter: reduced number of samples in Simpson's integration

[Bill Spitzak]

Ok to squash them together. Do you want me to do that?

It actually does not increase the runtime, because the two loops are only
adding every *other* sample. Thus the same number of samples are computed.

On Thu, Dec 17, 2015 at 1:23 PM, Oded Gabbay <oded.gabbay at gmail.com> wrote:

> On Sat, Dec 12, 2015 at 8:06 PM,  <spitzak at gmail.com> wrote:
> > From: Bill Spitzak <spitzak at gmail.com>
> >
> > With the cubic fix this is plenty accurate enough, far in excess of the
> pixman
> > fixed-point error limit. Likely even 16 samples is too many.
> > ---
> >  pixman/pixman-filter.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/pixman/pixman-filter.c b/pixman/pixman-filter.c
> > index 7c1da0d..4aafa51 100644
> > --- a/pixman/pixman-filter.c
> > +++ b/pixman/pixman-filter.c
> > @@ -190,7 +190,7 @@ integral (pixman_kernel_t reconstruct, double x1,
> >      else
> >      {
> >         /* Integration via Simpson's rule */
> > -#define N_SEGMENTS 128
> > +#define N_SEGMENTS 16
> >  #define SAMPLE(a1, a2)                                                 \
> >         (filters[reconstruct].func ((a1)) * filters[sample].func ((a2) /
> scale))
> >
> > --
> > 1.9.1
> >
> > _______________________________________________
> > Pixman mailing list
> > Pixman at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/pixman
>
> I think it is better to just squash this patch into the previous one,
> as it closely related and actually makes more sense to put them
> together so we can see the run time hasn't increased but actually
> decreased.
>
>       Oded
>
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