36 lines
933 B
C#
36 lines
933 B
C#
using System.Runtime.CompilerServices;
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using BenchmarkDotNet.Attributes;
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using BenchmarkDotNet.Running;
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BenchmarkRunner.Run<InverseSqrtBenchmarks>();
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[SimpleJob, MemoryDiagnoser(false)]
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public class InverseSqrtBenchmarks
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{
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[Benchmark]
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[Arguments(16.0f)]
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public float OneOverMathFSqrt(float number)
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{
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return 1.0f / MathF.Sqrt(number);
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}
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[Benchmark]
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[Arguments(16.0f)]
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public float Q_rsqrt(float number)
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{
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int i;
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float x2, y;
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const float threehalfs = 1.5F;
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x2 = number * 0.5F;
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y = number;
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i = Unsafe.As<float, int>(ref y); // evil floating point bit level hacking
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i = 0x5f3759df - (i >> 1); // what the fuck?
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y = Unsafe.As<int, float>(ref i);
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y = y * (threehalfs - (x2 * y * y)); // 1st iteration
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// y = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, this can be removed
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return y;
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}
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}
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