Restore struct residue args and add residue benchmark project

EvenPerfectBitScanner.Benchmarks/EvenPerfectBitScanner.Benchmarks.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="../PerfectNumbers.Core/PerfectNumbers.Core.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="BenchmarkDotNet" Version="0.13.12" />
+  </ItemGroup>
+
+</Project>

EvenPerfectBitScanner.Benchmarks/Program.cs

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+using BenchmarkDotNet.Running;
+
+namespace EvenPerfectBitScanner.Benchmarks;
+
+public static class Program
+{
+    public static void Main(string[] args)
+    {
+        BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);
+    }
+}
+

EvenPerfectBitScanner.Benchmarks/ResidueComputationBenchmarks.cs

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+using System.Numerics;
+using BenchmarkDotNet.Attributes;
+using PerfectNumbers.Core;
+
+namespace EvenPerfectBitScanner.Benchmarks;
+
+[MemoryDiagnoser]
+public class ResidueComputationBenchmarks
+{
+    [Params(3UL, 8191UL, 131071UL, 2147483647UL)]
+    public ulong Exponent { get; set; }
+
+    [Benchmark(Baseline = true)]
+    public (ulong Step10, ulong Step8, ulong Step3, ulong Step5) LegacyModulo()
+    {
+        ulong exponent = Exponent;
+        ulong step10 = ((exponent % 10UL) << 1) % 10UL;
+        ulong step8 = ((exponent & 7UL) << 1) & 7UL;
+        ulong step3 = ((exponent % 3UL) << 1) % 3UL;
+        ulong step5 = ((exponent % 5UL) << 1) % 5UL;
+        return (step10, step8, step3, step5);
+    }
+
+    [Benchmark]
+    public (ulong Step10, ulong Step8, ulong Step3, ulong Step5) ModMethodModulo()
+    {
+        UInt128 exponent128 = Exponent;
+        exponent128.Mod10_8_5_3(out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3);
+        ulong step10 = (mod10 << 1) % 10UL;
+        ulong step8 = (mod8 << 1) & 7UL;
+        ulong step3 = (mod3 << 1) % 3UL;
+        ulong step5 = (mod5 << 1) % 5UL;
+        return (step10, step8, step3, step5);
+    }
+}
+