## digitalmars.D.learn - vector Cross/Dot using core.simd?

• F i L (41/41) Aug 11 2012 I'm trying to write a Cross and Dot function using
• F i L (6/6) Aug 11 2012 On a side note, if I run the simple code:
• Sean Cavanaugh (15/19) Aug 11 2012 Some reference:
• F i L (5/21) Aug 12 2012 Awesome, I see XMM.HADDPS (amoung others) in core.simd now,
"F i L" <witte2008 gmail.com> writes:
```I'm trying to write a Cross and Dot function using
core.simd.float4 and DMD

The C++ code looks like:

from:
http://fastcpp.blogspot.com/2011/04/vector-cross-product-using-sse-code.html

inline __m128 CrossProduct(__m128 a, __m128 b)
{
return _mm_sub_ps (
_mm_mul_ps (
_mm_shuffle_ps(a, a, _MM_SHUFFLE(3, 0, 2, 1)),
_mm_shuffle_ps(b, b, _MM_SHUFFLE(3, 1, 0, 2))
),
_mm_mul_ps (
_mm_shuffle_ps(a, a, _MM_SHUFFLE(3, 1, 0, 2)),
_mm_shuffle_ps(b, b, _MM_SHUFFLE(3, 0, 2, 1))
)
);
}

I can see that core.simd.XMM supports a XMM.PSHUFB command I can
use with __simd(), but I'm not sure how to go about translate the
_MM_SHUFFLE() macro above.

For Dot product, I have a C# Mono.Simd function:

public static Vector4f Dot(Vector4f a, Vector4f b)
{
var result = a * b;

return result.X;
}

And I have no idea what XMM command HorizontalAdd would translate
to. But the Mono.Simd documentation says it performs:

{
return new Vector4f (
(a.X + a.Y), (a.Z + a.W),
(b.X + b.Y), (b.Z + b.W)
);
}

Does anyone know anything about SIMD operations that may be able
to help me translate these functions into a D equivalent? I would
```
Aug 11 2012
"F i L" <witte2008 gmail.com> writes:
```On a side note, if I run the simple code:

void16 a = 0, b = 0;
void16 r = __simd(XMM.PSHUFB, a, b);
writeln(r.array);

I get the following error:

Internal error: e2ir.c 3817
```
Aug 11 2012
Sean Cavanaugh <WorksOnMyMachine gmail.com> writes:
```On 8/11/2012 8:23 PM, F i L wrote:
I'm trying to write a Cross and Dot function using core.simd.float4 and DMD

Does anyone know anything about SIMD operations that may be able to help
me translate these functions into a D equivalent? I would very much

Some reference:

C++ simd intrinsic for dot product (requires SSE 4.1, very modern)
_mm_dp_ps

C++ simd instrinsic for horizontal add (requires SSE3, also reasonably
modern)

If you are on SSE2 (which is the base spec for x64) and also the minimum
CPU target we use at work for commercial game development, you are stuck
doing shuffles and adds for dot product, which effectively process these
operations as scalar).

Ideally one of the sides of the dot product is an array and you can
vectorize the dot product itself (1 vector vs 4 others, or 4 v 4).  This
is common when setting up shapes like view frustum culling (point tested
against 6-8 extruded planes in an array)
```
Aug 11 2012
"F i L" <witte2008 gmail.com> writes:
```Sean Cavanaugh wrote:
Some reference:

C++ simd intrinsic for dot product (requires SSE 4.1, very
modern)
_mm_dp_ps

Good to know, thanks!

C++ simd instrinsic for horizontal add (requires SSE3, also
reasonably modern)

Awesome, I see XMM.HADDPS (amoung others) in core.simd now,
thanks again!

If you are on SSE2 (which is the base spec for x64) and also
the minimum CPU target we use at work for commercial game
development, you are stuck doing shuffles and adds for dot
product, which effectively process these operations as scalar).

Ideally one of the sides of the dot product is an array and you
can vectorize the dot product itself (1 vector vs 4 others, or
4 v 4).  This is common when setting up shapes like view
frustum culling (point tested against 6-8 extruded planes in an
array)

Thanks for the info.
```
Aug 12 2012