[Mplayer-cvslog] CVS: main/drivers/radeon README,1.14,1.15

Michael Niedermayer michaelni at gmx.at
Thu Jan 3 13:27:25 CET 2002


Hi

On Thursday 03 January 2002 11:17, Nick Kurshev wrote:
> Hello, Michael!
>
> On Wed, 2 Jan 2002 13:11:19 +0100 you wrote:
> > Hi
> >
> > On Wednesday 02 January 2002 12:57, Nick Kurshev wrote:
> > [...]
> >
> > > > what about decreasing hue range to -100..+100, and using sin/cos
> > > > lookup table?
> > >
> > > We'll lose precision.
> >
> > do some interpolation (with a table & cubic interpolation it will be more
> > than precise enough)
>
> I already solved this problem with generic_math.h which perform linear
> interpolation by 1.8 degree step.
> But there is other BIGGEST problem. This driver violates rule: "No float in
> the kernel" :( Well there is way to avoid this problem (from
> linux-kernel at vger.kernel.org):
[...]
u could use fixpoint math
1<<24 == "1.0"
int64_t a,b,c
ADD(a,b) a + b
MUL(a,b) (a*b + (1<<23))>>24
DIV(a,b) (a<<24)/b 	//not correctly rounded ...

Michael



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