[Bug 27901] GLSL cos/sin functions broken on Mesa R600 driver

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=27901

--- Comment #9 from Conn Clark <conn.o.clark at gmail.com> 2010-05-20 18:08:28 PDT ---
On Thu, May 20, 2010 at 5:40 PM,  <bugzilla-daemon at freedesktop.org> wrote:
> https://bugs.freedesktop.org/show_bug.cgi?id=27901
>
> --- Comment #8 from Alain Perrot <alain.perrot at gmail.com> 2010-05-20 17:40:21 PDT ---
> Created an attachment (id=35777)
 View: https://bugs.freedesktop.org/attachment.cgi?id=35777
 Review: https://bugs.freedesktop.org/review?bug=27901&attachment=35777

>  View: https://bugs.freedesktop.org/attachment.cgi?id=35777
>  Review: https://bugs.freedesktop.org/review?bug=27901&attachment=35777
>
> Alternative assemble_TRIG fix
>
> I can confirm that your patch seems to work for me too.
>
> By the way, you beat me at posting a working patch here :-)
>
> I also figured out that the 0.5 special constant was an issue in your patch,
> and I managed to get a working assemble_TRIG function which implements the
> following instruction sequence (lightly different of yours) to normalize the
> angle:
>
> MULADD  tmp.x, angle, 1/(2*PI), 0.5
> FRACT   tmp.x, tmp.x
> ADD     tmp.y, tmp.x, 1
> CNDGE   tmp.x, tmp.x, tmp.x, tmp.y
> MULADD  tmp.x, tmp.x, 2*PI, -PI
>
> I don't known if it is better or worse than yours beside the fact that it use
> only one helper variable.
>
> I attached my patch (updated to use the same extended value of PI than yours)
> which fix the assemble_TRIG function, but not the assemble_SCS one.
>
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Alain,

Its a tough call on who's is the better solution. Yours uses one less
temp reg and mine will allow for a couple of operations to be done in
parallel in the future. I guess we both deserve a pat on the back and
leave it to someone more experienced to make the call on which one to
choose.

Good job

Conn

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