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xoofx/BatchSimdDot.cs

Created September 2, 2024 06:36
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BatchSimdDot Example
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BatchSimdDot.cs
// Comment about https://mastodon.social/@brandewinder@hachyderm.io/113064780292323247
// https://brandewinder.com/2024/09/01/should-i-use-simd-vectors/
using System.Numerics;
using System.Runtime.InteropServices;
using System.Runtime.Intrinsics;
public class VectorProcessor
{
public static float Take2(float[] left, float[] right)
{
var size = left.Length;
var s1 = new ReadOnlySpan<float>(left);
var s2 = new ReadOnlySpan<float>(right);
var total = 0.0f;
// Use Vector<float>.Count, don't hardcode
for (int i = 0; i < size / Vector<float>.Count; i++)
{
var s = Vector<float>.Count * i;
var v1 = new Vector<float>(s1.Slice(s, Vector<float>.Count));
var v2 = new Vector<float>(s2.Slice(s, Vector<float>.Count));
var diff = v1 - v2;
total += Vector.Dot(diff, diff);
}
return MathF.Sqrt(total);
}
public static float TakeFaster(float[] left, float[] right)
{
var s1 = MemoryMarshal.Cast<float, Vector<float>>(new ReadOnlySpan<float>(left));
var s2 = MemoryMarshal.Cast<float, Vector<float>>(new ReadOnlySpan<float>(right));
var total = 0.0f;
for (int i = 0; i < s1.Length && i < s2.Length; i++)
{
var v1 = s1[i];
var v2 = s2[i];
var diff = v1 - v2;
total += Vector.Dot(diff, diff);
}
return MathF.Sqrt(total);
}
}
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