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