58 lines
1.7 KiB
C#
58 lines
1.7 KiB
C#
using System.Runtime.CompilerServices;
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using BenchmarkDotNet.Attributes;
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using BenchmarkDotNet.Jobs;
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using PerfectNumbers.Core;
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namespace EvenPerfectBitScanner.Benchmarks;
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[SimpleJob(RuntimeMoniker.Net80, launchCount: 1, warmupCount: 1, iterationCount: 3)]
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[MemoryDiagnoser]
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public class Mod6ULongBenchmarks
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{
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private static readonly byte[] Mod6Lookup = [0, 3, 4, 1, 2, 5];
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[MethodImpl(MethodImplOptions.AggressiveInlining)]
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public static ulong Mod6(ulong value) => Mod6Lookup[(int)(((value % 3UL) << 1) | (value & 1UL))];
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[Params(3UL, 131071UL, ulong.MaxValue - 1024UL)]
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public ulong Value { get; set; }
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/// <summary>
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/// `% 6` baseline; recorded 0.264 ns at Value 3, 0.262 ns at 131071, and 0.271 ns near ulong.Max.
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/// </summary>
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[Benchmark(Baseline = true)]
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public ulong ModuloOperator()
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{
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return Value % 6UL;
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}
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/// <summary>
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/// Division-based reduction (`value / 6`); timings were 0.277 ns, 0.284 ns, and 0.287 ns across the three start values.
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/// </summary>
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[Benchmark]
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public ulong DivisionBased()
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{
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ulong quotient = Value / 6UL;
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return Value - quotient * 6UL;
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}
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/// <summary>
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/// FastDivHigh helper; significantly slower at 1.24 ns (Value 3), 1.04 ns (131071), and 1.17 ns (near ulong.Max).
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/// </summary>
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[Benchmark]
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public ulong FastDivHigh()
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{
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ulong quotient = Value.FastDiv64(6UL, (ulong)(((UInt128)1 << 64) / 6UL));
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return Value - quotient * 6UL;
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}
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/// <summary>
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/// Lookup-based helper; cost 0.461 ns at Value 3, 0.467 ns at 131071, 0.467 ns near ulong.Max—about 1.7x slower than the modulo.
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/// </summary>
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[Benchmark]
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public ulong ExtensionMethod()
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{
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return Mod6(Value);
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}
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}
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