[Mesa-dev] [PATCH] gallium/docs: fix NRM, NRM4 docs

[Brian Paul]

DX9 ps3/vs3 has a NRM (3-component) instruction so there's that 
potential use, I guess.

-Brian

On 10/31/2014 04:52 PM, Jose Fonseca wrote:
> Looks good.
>
> AFAICT these opcodes are never generated, and no driver except llvmpipe/softpipe/svga supports them.  The performance is dominated by the square root reciprocate which has its own opcode, RSQ, so personally I'm for removing these opcodes.
>
> Jose
>
> ________________________________________
> From: mesa-dev <mesa-dev-bounces at lists.freedesktop.org> on behalf of Brian Paul <brianp at vmware.com>
> Sent: 31 October 2014 22:09
> To: mesa-dev at lists.freedesktop.org
> Subject: [Mesa-dev] [PATCH] gallium/docs: fix NRM, NRM4 docs
>
> Need to do a sqrt().
>
> FWIW, the html that Sphinx 1.1.3 generates for the math expressions
> looks completely broken.
> ---
>   src/gallium/docs/source/tgsi.rst |   36 ++++++++++++++++++++++++------------
>   1 file changed, 24 insertions(+), 12 deletions(-)
>
> diff --git a/src/gallium/docs/source/tgsi.rst b/src/gallium/docs/source/tgsi.rst
> index 7d5918f..2e01971 100644
> --- a/src/gallium/docs/source/tgsi.rst
> +++ b/src/gallium/docs/source/tgsi.rst
> @@ -837,16 +837,37 @@ This instruction replicates its result.
>   .. opcode:: NRM - 3-component Vector Normalise
>
>   .. math::
> +
> +  u = src.x \times src.x + src.y \times src.y + src.z \times src.z
>
> -  dst.x = src.x / (src.x \times src.x + src.y \times src.y + src.z \times src.z)
> +  v = \frac{1}{\sqrt{u}}
>
> -  dst.y = src.y / (src.x \times src.x + src.y \times src.y + src.z \times src.z)
> +  dst.x = src.x \times v
>
> -  dst.z = src.z / (src.x \times src.x + src.y \times src.y + src.z \times src.z)
> +  dst.y = src.y \times v
> +
> +  dst.z = src.z \times v
>
>     dst.w = 1
>
>
> +.. opcode:: NRM4 - 4-component Vector Normalise
> +
> +.. math::
> +
> +  u = src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w
> +
> +  v = \frac{1}{\sqrt{u}}
> +
> +  dst.x = src.x \times v
> +
> +  dst.y = src.y \times v
> +
> +  dst.z = src.z \times v
> +
> +  dst.w = src.w \times v
> +
> +
>   .. opcode:: DIV - Divide
>
>   .. math::
> @@ -1888,15 +1909,6 @@ Some require glsl version 1.30 (UIF/BREAKC/SWITCH/CASE/DEFAULT/ENDSWITCH).
>      Ends a switch expression.
>
>
> -.. opcode:: NRM4 - 4-component Vector Normalise
> -
> -This instruction replicates its result.
> -
> -.. math::
> -
> -  dst = \frac{src.x}{src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w}
> -
> -
>   Interpolation ISA
>   ^^^^^^^^^^^^^^^^^
>
> --
> 1.7.10.4
>
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