Extension methods benchmarked. Slower alternatives replaced.

EvenPerfectBitScanner.Benchmarks/Mod10UInt128Benchmarks.cs

@@ -1,5 +1,4 @@
 using BenchmarkDotNet.Attributes;
-using PerfectNumbers.Core;
 
 namespace EvenPerfectBitScanner.Benchmarks;
 
@@ -15,38 +14,45 @@ public class Mod10UInt128Benchmarks
 		return Value % 10UL;
 	}
 
+	/// <summary>
+	/// Fastest
+	/// </summary>
 	[Benchmark]
 	public ulong ModWithHighLowModulo()
 	{
-		// Split and fold under mod 10: 2^64 ≡ 6 (mod 10)
-		ulong value = (ulong)Value;
-		ulong high = value >> 64;
-		ulong low = value;
-                ulong highRem = high % 10UL;
-                ulong lowRem = low % 10UL;
-                ulong combined = lowRem + highRem * 6UL;
-                return combined % 10UL;
+		return ModWithHighLowModuloHelper(Value);
 	}
 
-    [Benchmark]
-    public ulong ModWithLoopModulo()
-    {
-		UInt128 value = Value;
+	private static ulong ModWithHighLowModuloHelper(UInt128 value128)
+	{
+		// Split and fold under mod 10: 2^64 ≡ 6 (mod 10)
+		ulong value = (ulong)value128;
+		return ((value % 10UL) + ((value >> 64) % 10UL) * 6UL) % 10UL;
+	}
+
+	[Benchmark]
+	public ulong ModWithLoopModulo()
+	{
+		return ModWithLoopModuloHelper(Value);
+	}
+
+	private static ulong ModWithLoopModuloHelper(UInt128 value)
+	{
 		UInt128 zero = UInt128.Zero;
 		if (value == zero)
 			return 0UL;
 
 		ulong result = (ulong)value;
-		UInt128 high = value >> 64;
+		value >>= 64;
 
-		while (high != zero)
+		while (value != zero)
 		{
 			// 2^64 ≡ 6 (mod 10)
-                        result = (result + (ulong)high * 6UL) % 10UL;
-                        high >>= 64;
-                }
+			result = (result + (ulong)value * 6UL) % 10UL;
+			value >>= 64;
+		}
 
-                return result % 10UL;
-    }
+		return result % 10UL;
+	}
 }
 

EvenPerfectBitScanner.Benchmarks/Mod10UIntBenchmarks.cs

@@ -1,3 +1,4 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
 using PerfectNumbers.Core;
@@ -8,10 +9,16 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod10UIntBenchmarks
 {
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static uint Mod10(uint value) => value - (uint)((value * UIntExtensions.Mod5Mask) >> 35) * 10U;
+
     [Params(10U, 2047U, 65535U, 2147483647U)]
     public uint Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public uint ModuloOperator()
     {
         return Value % 10U;
@@ -20,7 +27,7 @@ public class Mod10UIntBenchmarks
     [Benchmark]
     public uint ExtensionMethod()
     {
-        return Value.Mod10();
+        return Mod10(Value);
     }
 }
 

EvenPerfectBitScanner.Benchmarks/Mod10ULongBenchmarks.cs

@@ -1,4 +1,3 @@
-using System.Numerics;
 using BenchmarkDotNet.Attributes;
 using PerfectNumbers.Core;
 
@@ -16,7 +15,10 @@ public class Mod10ULongBenchmarks
 		return Value % 10UL;
     }
 
-    [Benchmark]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark]
     public ulong ModMethodModulo()
     {
         return Value.Mod10();

EvenPerfectBitScanner.Benchmarks/Mod10_8_5_3Benchmarks.cs

@@ -1,4 +1,3 @@
-using System.Numerics;
 using BenchmarkDotNet.Attributes;
 using PerfectNumbers.Core;
 
@@ -10,7 +9,10 @@ public class Mod10_8_5_3Benchmarks
     [Params(3UL, 8191UL, 131071UL, 2147483647UL)]
     public ulong Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public (ulong Mod10, ulong Mod8, ulong Mod3, ulong Mod5) ModuloOperator()
     {
         ulong value = Value;

EvenPerfectBitScanner.Benchmarks/Mod10_8_5_3PropertiesBenchmarks.cs

@@ -1,4 +1,3 @@
-using System.Numerics;
 using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using PerfectNumbers.Core;
@@ -36,10 +35,13 @@ public class Mod10_8_5_3PropertiesBenchmarks
         return rem >= 5UL ? rem - 5UL : rem;
     }
 
-    [Params(3UL, 8191UL, 131071UL, 2147483647UL)]
+    [Params(3UL, 6UL, 128UL, 256UL, 2_047UL, 8_191UL, 65_535UL, 131_071UL, 2_147_483_647UL, ulong.MaxValue - 1_024UL, ulong.MaxValue - 511UL, ulong.MaxValue - 255UL, ulong.MaxValue - 127UL, ulong.MaxValue - 63UL, ulong.MaxValue - 31UL, ulong.MaxValue - 17UL)]
     public ulong Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public (ulong Mod10, ulong Mod8, ulong Mod5, ulong Mod3) LegacyModulo()
     {
 		UInt128 value = Value;
@@ -53,12 +55,7 @@ public class Mod10_8_5_3PropertiesBenchmarks
     [Benchmark]
     public (ulong Mod10, ulong Mod8, ulong Mod3, ulong Mod5) ModMethodModulo()
     {
-		Value.Mod10_8_5_3(out var mod10, out ulong mod8, out ulong mod5, out ulong mod3);
-		Mod10R = mod10;
-		Mod8R = mod8;
-		Mod5R = mod5;
-		Mod3R = mod3;
-
+		Value.Mod10_8_5_3(out Mod10R, out Mod8R, out Mod5R, out Mod3R);
         return (Mod10R, Mod8R, Mod3R, Mod5R);
     }
 }

EvenPerfectBitScanner.Benchmarks/Mod10_8_5_3StepsBenchmarks.cs

@@ -1,4 +1,3 @@
-using System.Numerics;
 using BenchmarkDotNet.Attributes;
 using PerfectNumbers.Core;
 
@@ -14,19 +13,21 @@ public class Mod10_8_5_3StepsBenchmarks
     public (ulong Mod10, ulong Mod8, ulong Mod3, ulong Mod5) LegacyModulo()
     {
 		UInt128 value = Value;
-		ulong mod10 = (ulong)(value % 10UL) % 10UL;
-		ulong mod8 = (ulong)(value % 8UL);
-		ulong mod3 = (ulong)(value % 3UL);
-		ulong mod5 = (ulong)(value % 5UL);
+		ulong mod10 = (((ulong)(value % 10UL)) << 1) % 10UL;
+		ulong mod8 = (((ulong)(value & 7UL)) << 1) & 7UL;
+		ulong mod5 = (((ulong)(value % 5UL)) << 1) % 5UL;
+		ulong mod3 = (((ulong)(value % 3UL)) << 1) % 3UL;
         return (mod10, mod8, mod3, mod5);
     }
 
-    [Benchmark]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark]
     public (ulong Mod10, ulong Mod8, ulong Mod3, ulong Mod5) ModMethodModulo()
     {
-		Value.Mod10_8_5_3(out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3);
+		Value.Mod10_8_5_3Steps(out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3);
 		// Step residues for q += 2*p
-                mod10 %= 10UL;
         return (mod10, mod8, mod3, mod5);
     }
 }

EvenPerfectBitScanner.Benchmarks/Mod11UIntBenchmarks.cs

@@ -1,6 +1,6 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
-using PerfectNumbers.Core;
 
 namespace EvenPerfectBitScanner.Benchmarks;
 
@@ -8,10 +8,27 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod11UIntBenchmarks
 {
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static uint Mod11(uint value)
+	{
+		uint remainder = 0U;
+		while (value != 0U)
+		{
+			remainder += value & 1023U;
+			value >>= 10;
+			remainder -= 11U * (remainder / 11U);
+		}
+
+		return remainder;
+	}
+
     [Params(11U, 2047U, 65535U, 2147483647U)]
     public uint Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public uint ModuloOperator()
     {
         return Value % 11U;
@@ -20,7 +37,7 @@ public class Mod11UIntBenchmarks
     [Benchmark]
     public uint ExtensionMethod()
     {
-        return Value.Mod11();
+        return Mod11(Value);
     }
 }
 

EvenPerfectBitScanner.Benchmarks/Mod11ULongBenchmarks.cs

@@ -1,6 +1,6 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
-using PerfectNumbers.Core;
 
 namespace EvenPerfectBitScanner.Benchmarks;
 
@@ -8,10 +8,25 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod11ULongBenchmarks
 {
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod11(ulong value)
+	{
+		ulong remainder = ((uint)value % 11U) + ((uint)(value >> 32) % 11U) << 2;
+		while (remainder >= 11UL)
+		{
+			remainder -= 11UL;
+		}
+
+		return remainder;
+	}
+
     [Params(11UL, 8191UL, 131071UL, 2147483647UL, ulong.MaxValue - 127UL)]
     public ulong Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public ulong ModuloOperator()
     {
         return Value % 11UL;
@@ -20,7 +35,7 @@ public class Mod11ULongBenchmarks
     [Benchmark]
     public ulong ExtensionMethod()
     {
-        return Value.Mod11();
+        return Mod11(Value);
     }
 }
 

EvenPerfectBitScanner.Benchmarks/Mod11_7_5_3Benchmarks.cs

@@ -1,32 +1,92 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
-using PerfectNumbers.Core;
 
 namespace EvenPerfectBitScanner.Benchmarks;
 
 [MemoryDiagnoser]
 public class Mod11_7_5_3Benchmarks
 {
+	private static readonly byte[] Mod7ByteCoefficients = [1, 4, 2, 1, 4, 2, 1, 4];
+	private static readonly byte[] Mod11ByteCoefficients = [1, 3, 9, 5, 4, 1, 3, 9];
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	private static ulong ReduceMod7(uint value)
+	{
+		while (value >= 7U)
+		{
+			value = (value >> 3) + (value & 7U);
+			if (value >= 7U && value < 14U)
+			{
+				value -= 7U;
+			}
+		}
+
+		return value;
+	}
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	private static ulong ReduceMod11(uint value)
+	{
+		while (value >= 11U)
+		{
+			value = (value & 15U) + ((value >> 4) * 5U);
+			if (value >= 11U && value < 22U)
+			{
+				value -= 11U;
+			}
+		}
+
+		return value;
+	}
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	private static void Mod11_7_5_3(ulong value, out ulong mod11, out ulong mod7, out ulong mod5, out ulong mod3)
+	{
+		uint mod3And5Accumulator = 0U;
+		uint mod7Accumulator = 0U;
+		uint mod11Accumulator = 0U;
+
+		int index = 0;
+		byte current;
+		ulong temp = value;
+
+		byte[] mod7ByteCoefficients = Mod7ByteCoefficients;
+		byte[] mod11ByteCoefficients = Mod11ByteCoefficients;
+		do
+		{
+			current = (byte)temp;
+			mod3And5Accumulator += current;
+			mod7Accumulator += (uint)(current * mod7ByteCoefficients[index]);
+			mod11Accumulator += (uint)(current * mod11ByteCoefficients[index]);
+
+			temp >>= 8;
+			index++;
+		}
+		while (temp != 0UL);
+
+		mod3 = mod3And5Accumulator % 3;
+		mod5 = mod3And5Accumulator % 5;
+		mod7 = (uint)ReduceMod7(mod7Accumulator);
+		mod11 = (uint)ReduceMod11(mod11Accumulator);
+	}
+
     [Params(3UL, 8191UL, 131071UL, 2147483647UL)]
     public ulong Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public (ulong Mod11, ulong Mod7, ulong Mod5, ulong Mod3) ModuloOperator()
     {
         ulong value = Value;
         return (value % 11UL, value % 7UL, value % 5UL, value % 3UL);
     }
 
-    [Benchmark]
-    public (ulong Mod11, ulong Mod7, ulong Mod5, ulong Mod3) ExtensionMethods()
-    {
-        ulong value = Value;
-        return (value.Mod11(), value.Mod7(), value.Mod5(), value.Mod3());
-    }
-
     [Benchmark]
     public (ulong Mod11, ulong Mod7, ulong Mod5, ulong Mod3) CombinedMethod()
     {
-        Value.Mod11_7_5_3(out ulong mod11, out ulong mod7, out ulong mod5, out ulong mod3);
+        Mod11_7_5_3(Value, out ulong mod11, out ulong mod7, out ulong mod5, out ulong mod3);
         return (mod11, mod7, mod5, mod3);
     }
 }

EvenPerfectBitScanner.Benchmarks/Mod128UInt128Benchmarks.cs

@@ -1,4 +1,3 @@
-using System.Numerics;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
 using PerfectNumbers.Core;
@@ -12,12 +11,16 @@ public class Mod128UInt128Benchmarks
     [Params(128UL, 8191UL, 131071UL, 2147483647UL, ulong.MaxValue - 511UL)]
     public UInt128 Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	[Benchmark(Baseline = true)]
     public ulong ModuloOperator()
     {
         return (ulong)(Value % 128UL);
     }
 
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	/// <returns></returns>
     [Benchmark]
     public ulong ExtensionMethod()
     {

EvenPerfectBitScanner.Benchmarks/Mod128UIntBenchmarks.cs

@@ -1,6 +1,6 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
-using PerfectNumbers.Core;
 
 namespace EvenPerfectBitScanner.Benchmarks;
 
@@ -8,10 +8,17 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod128UIntBenchmarks
 {
-    [Params(128U, 2047U, 65535U, 2147483647U)]
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static uint Mod128(uint value) => value & 127U;
+
+    [Params(3UL, 5UL, 6UL, 8UL, 10UL, 11UL, 32UL, 64UL, 128UL, 256UL, 2_047UL, 8_191UL, 65_535UL, 131_071UL, 2_147_483_647UL, uint.MaxValue - 1_024UL, uint.MaxValue - 511UL, uint.MaxValue - 255UL, uint.MaxValue - 127UL, uint.MaxValue - 63UL, uint.MaxValue - 31UL, uint.MaxValue - 17UL, uint.MaxValue)]
     public uint Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest most of the times. It's usually much faster than it's slower.
+	/// </summary>
+	/// <returns></returns>
+	[Benchmark(Baseline = true)]
     public uint ModuloOperator()
     {
         return Value % 128U;
@@ -20,7 +27,7 @@ public class Mod128UIntBenchmarks
     [Benchmark]
     public uint ExtensionMethod()
     {
-        return Value.Mod128();
+        return Mod128(Value);
     }
 }
 

EvenPerfectBitScanner.Benchmarks/Mod128ULongBenchmarks.cs

@@ -8,15 +8,19 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod128ULongBenchmarks
 {
-    [Params(128UL, 8191UL, 131071UL, 2147483647UL, ulong.MaxValue - 255UL)]
+    [Params(3UL, 5UL, 6UL, 8UL, 10UL, 11UL, 32UL, 64UL, 128UL, 256UL, 2_047UL, 8_191UL, 65_535UL, 131_071UL, 2_147_483_647UL, uint.MaxValue - 1_024UL, uint.MaxValue - 511UL, uint.MaxValue - 255UL, uint.MaxValue - 127UL, uint.MaxValue - 63UL, uint.MaxValue - 31UL, uint.MaxValue - 17UL, uint.MaxValue)]
     public ulong Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	[Benchmark(Baseline = true)]
     public ulong ModuloOperator()
     {
         return Value % 128UL;
     }
 
+	/// <summary>
+	/// Usually fastest for high values. It's slower for some values and faster for other.
+	/// </summary>
+	/// <returns></returns>
     [Benchmark]
     public ulong ExtensionMethod()
     {

EvenPerfectBitScanner.Benchmarks/Mod3UIntBenchmarks.cs

@@ -20,7 +20,7 @@ public class Mod3UIntBenchmarks
     [Benchmark]
     public uint ExtensionMethod()
     {
-        return Value.Mod3();
+        return UIntExtensions.Mod3(Value);
     }
 }
 

EvenPerfectBitScanner.Benchmarks/Mod3ULongBenchmarks.cs

@@ -1,3 +1,4 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
 using PerfectNumbers.Core;
@@ -8,10 +9,22 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod3ULongBenchmarks
 {
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	private static ulong Mod3(ulong value) =>
+			(
+				(uint)(value & ULongExtensions.WordBitMask) +
+				(uint)((value >> 16) & ULongExtensions.WordBitMask) +
+				(uint)((value >> 32) & ULongExtensions.WordBitMask) +
+				(uint)((value >> 48) & ULongExtensions.WordBitMask)
+			) % 3;
+
     [Params(3UL, 8191UL, 131071UL, 2147483647UL, ulong.MaxValue - 17UL)]
     public ulong Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public ulong ModuloOperator()
     {
         return Value % 3UL;
@@ -20,7 +33,7 @@ public class Mod3ULongBenchmarks
     [Benchmark]
     public ulong ExtensionMethod()
     {
-        return Value.Mod3();
+        return Mod3(Value);
     }
 }
 

EvenPerfectBitScanner.Benchmarks/Mod5UIntBenchmarks.cs

@@ -8,7 +8,7 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod5UIntBenchmarks
 {
-    [Params(5U, 2047U, 65535U, 2147483647U)]
+    [Params(3UL, 5UL, 6UL, 8UL, 10UL, 11UL, 32UL, 64UL, 128UL, 256UL, 2_047UL, 8_191UL, 65_535UL, 131_071UL, 2_147_483_647UL, uint.MaxValue - 1_024UL, uint.MaxValue - 511UL, uint.MaxValue - 255UL, uint.MaxValue - 127UL, uint.MaxValue - 63UL, uint.MaxValue - 31UL, uint.MaxValue - 17UL, uint.MaxValue)]
     public uint Value { get; set; }
 
     [Benchmark(Baseline = true)]
@@ -17,7 +17,10 @@ public class Mod5UIntBenchmarks
         return Value % 5U;
     }
 
-    [Benchmark]
+	/// <summary>
+	/// Mixed results. Sometimes it's faster, in higher ranges, sometimes it's slower.
+	/// </summary>
+	[Benchmark]
     public uint ExtensionMethod()
     {
         return Value.Mod5();

EvenPerfectBitScanner.Benchmarks/Mod5ULongBenchmarks.cs

@@ -1,3 +1,4 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
 using PerfectNumbers.Core;
@@ -8,10 +9,22 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod5ULongBenchmarks
 {
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod5(ulong value) =>
+			(
+				(uint)(value & ULongExtensions.WordBitMask) +
+				(uint)((value >> 16) & ULongExtensions.WordBitMask) +
+				(uint)((value >> 32) & ULongExtensions.WordBitMask) +
+				(uint)((value >> 48) & ULongExtensions.WordBitMask)
+			) % 5;
+
     [Params(5UL, 8191UL, 131071UL, 2147483647UL, ulong.MaxValue - 31UL)]
     public ulong Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public ulong ModuloOperator()
     {
         return Value % 5UL;
@@ -20,7 +33,7 @@ public class Mod5ULongBenchmarks
     [Benchmark]
     public ulong ExtensionMethod()
     {
-        return Value.Mod5();
+        return Mod5(Value);
     }
 }
 

EvenPerfectBitScanner.Benchmarks/Mod6ComparisonBenchmarks.cs

@@ -1,4 +1,4 @@
-using System.Numerics;
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
 using PerfectNumbers.Core;
@@ -9,6 +9,11 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod6ComparisonBenchmarks
 {
+	private static readonly byte[] Mod6Lookup = [0, 3, 4, 1, 2, 5];
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod6(ulong value) => Mod6Lookup[(int)(((value % 3UL) << 1) | (value & 1UL))];
+
     private const int Iterations = 10_000_000;
     private const ulong Divisor = 6UL;
     private static readonly ulong FastDivMul = (ulong)(((UInt128)1 << 64) / Divisor);
@@ -71,7 +76,7 @@ public class Mod6ComparisonBenchmarks
 
         for (int i = 0; i < Iterations; i++)
         {
-            checksum += value.Mod6();
+            checksum += Mod6(value);
             value += (ulong)((i & 15) + 1);
         }
 

EvenPerfectBitScanner.Benchmarks/Mod6UIntBenchmarks.cs

@@ -1,6 +1,6 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
-using PerfectNumbers.Core;
 
 namespace EvenPerfectBitScanner.Benchmarks;
 
@@ -8,10 +8,18 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod6UIntBenchmarks
 {
+	private static readonly byte[] Mod6Lookup = [0, 3, 4, 1, 2, 5];
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static uint Mod6(uint value) => Mod6Lookup[(int)(((value % 3U) << 1) | (value & 1U))];
+
     [Params(6U, 2047U, 65535U, 2147483647U)]
     public uint Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public uint ModuloOperator()
     {
         return Value % 6U;
@@ -20,7 +28,7 @@ public class Mod6UIntBenchmarks
     [Benchmark]
     public uint ExtensionMethod()
     {
-        return Value.Mod6();
+        return Mod6(Value);
     }
 }
 

EvenPerfectBitScanner.Benchmarks/Mod6ULongBenchmarks.cs

@@ -1,4 +1,4 @@
-using System.Numerics;
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
 using PerfectNumbers.Core;
@@ -9,13 +9,20 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod6ULongBenchmarks
 {
+	private static readonly byte[] Mod6Lookup = [0, 3, 4, 1, 2, 5];
     private static readonly ulong Divisor = 6UL;
     private static readonly ulong FastDivMul = (ulong)(((UInt128)1 << 64) / Divisor);
 
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod6(ulong value) => Mod6Lookup[(int)(((value % 3UL) << 1) | (value & 1UL))];
+
     [Params(3UL, 131071UL, ulong.MaxValue)]
     public ulong Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public ulong ModuloOperator()
     {
                 return Value % Divisor;
@@ -38,6 +45,6 @@ public class Mod6ULongBenchmarks
     [Benchmark]
     public ulong ExtensionMethod()
     {
-        return Value.Mod6();
+        return Mod6(Value);
     }
 }

EvenPerfectBitScanner.Benchmarks/Mod7UInt128Benchmarks.cs

@@ -17,7 +17,11 @@ public class Mod7UInt128Benchmarks
         return (ulong)(Value % 7UL);
     }
 
-    [Benchmark]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	/// <returns></returns>
+	[Benchmark]
     public ulong ExtensionMethod()
     {
         return Value.Mod7();

EvenPerfectBitScanner.Benchmarks/Mod7UIntBenchmarks.cs

@@ -1,6 +1,6 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
-using PerfectNumbers.Core;
 
 namespace EvenPerfectBitScanner.Benchmarks;
 
@@ -8,10 +8,30 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod7UIntBenchmarks
 {
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static uint Mod7(uint value)
+	{
+		uint remainder = 0U;
+		while (value != 0U)
+		{
+			remainder += value & 7U;
+			value >>= 3;
+			if (remainder >= 7U)
+			{
+				remainder -= 7U;
+			}
+		}
+
+		return remainder >= 7U ? remainder - 7U : remainder;
+	}
+
     [Params(7U, 2047U, 65535U, 2147483647U)]
     public uint Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public uint ModuloOperator()
     {
         return Value % 7U;
@@ -20,7 +40,7 @@ public class Mod7UIntBenchmarks
     [Benchmark]
     public uint ExtensionMethod()
     {
-        return Value.Mod7();
+        return Mod7(Value);
     }
 }
 

EvenPerfectBitScanner.Benchmarks/Mod7ULongBenchmarks.cs

@@ -1,6 +1,6 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
-using PerfectNumbers.Core;
 
 namespace EvenPerfectBitScanner.Benchmarks;
 
@@ -8,10 +8,25 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod7ULongBenchmarks
 {
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod7(ulong value)
+	{
+		ulong remainder = ((uint)value % 7U) + (((uint)(value >> 32) % 7U) << 2);
+		while (remainder >= 7UL)
+		{
+			remainder -= 7UL;
+		}
+
+		return remainder;
+	}
+
     [Params(7UL, 8191UL, 131071UL, 2147483647UL, ulong.MaxValue - 63UL)]
     public ulong Value { get; set; }
 
-    [Benchmark(Baseline = true)]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark(Baseline = true)]
     public ulong ModuloOperator()
     {
         return Value % 7UL;
@@ -20,7 +35,7 @@ public class Mod7ULongBenchmarks
     [Benchmark]
     public ulong ExtensionMethod()
     {
-        return Value.Mod7();
+        return Mod7(Value);
     }
 }
 

EvenPerfectBitScanner.Benchmarks/Mod8UInt128Benchmarks.cs

@@ -1,4 +1,3 @@
-using System.Numerics;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
 using PerfectNumbers.Core;
@@ -18,7 +17,10 @@ public class Mod8UInt128Benchmarks
         return (ulong)(Value % 8UL);
     }
 
-    [Benchmark]
+	/// <summary>
+	/// Fastest
+	/// </summary>
+	[Benchmark]
     public ulong ExtensionMethod()
     {
         return Value.Mod8();

EvenPerfectBitScanner.Benchmarks/Mod8UIntBenchmarks.cs

@@ -17,6 +17,9 @@ public class Mod8UIntBenchmarks
         return Value % 8U;
     }
 
+	/// <summary>
+	/// Fastest
+	/// </summary>
     [Benchmark]
     public uint ExtensionMethod()
     {

EvenPerfectBitScanner.Benchmarks/Mod8ULongBenchmarks.cs

@@ -1,6 +1,6 @@
+using System.Runtime.CompilerServices;
 using BenchmarkDotNet.Attributes;
 using BenchmarkDotNet.Jobs;
-using PerfectNumbers.Core;
 
 namespace EvenPerfectBitScanner.Benchmarks;
 
@@ -8,19 +8,25 @@ namespace EvenPerfectBitScanner.Benchmarks;
 [MemoryDiagnoser]
 public class Mod8ULongBenchmarks
 {
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod8(ulong value) => value & 7UL;
+
     [Params(8UL, 8191UL, 131071UL, 2147483647UL, ulong.MaxValue - 127UL)]
     public ulong Value { get; set; }
 
+	/// <summary>
+	/// Fastest
+	/// </summary>
     [Benchmark(Baseline = true)]
     public ulong ModuloOperator()
     {
         return Value % 8UL;
     }
 
-    [Benchmark]
+	[Benchmark]
     public ulong ExtensionMethod()
     {
-        return Value.Mod8();
+        return Mod8(Value);
     }
 }
 

EvenPerfectBitScanner/Program.cs

@@ -3,7 +3,6 @@ using System.Globalization;
 using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Text;
-using System.Threading;
 using Open.Collections;
 using Open.Numeric.Primes;
 using PerfectNumbers.Core;
@@ -1674,7 +1673,7 @@ internal static class Program
 		// Optional: RLE blacklist and binary-threshold filters on p (safe only when configured)
 		if (p <= _rleHardMaxP)
 		{
-                   if (!_rleOnlyLast7 || p % 10UL == 7UL)
+                   if (!_rleOnlyLast7 || p.Mod10() == 7UL)
 			{
 				if (RleBlacklist.IsLoaded() && RleBlacklist.Matches(p))
 				{

PerfectNumbers.Core.Tests/UIntExtensionsTests.cs

@@ -13,7 +13,7 @@ public class UIntExtensionsTests
     [InlineData(uint.MaxValue)]
     public void Mod3_matches_operator(uint value)
     {
-        value.Mod3().Should().Be(value % 3U);
+        UIntExtensions.Mod3(value).Should().Be(value % 3U);
     }
 
     [Theory]
@@ -27,28 +27,6 @@ public class UIntExtensionsTests
         value.Mod5().Should().Be(value % 5U);
     }
 
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0U)]
-    [InlineData(1U)]
-    [InlineData(1234567890U)]
-    [InlineData(uint.MaxValue)]
-    public void Mod6_matches_operator(uint value)
-    {
-        value.Mod6().Should().Be(value % 6U);
-    }
-
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0U)]
-    [InlineData(1U)]
-    [InlineData(1234567890U)]
-    [InlineData(uint.MaxValue)]
-    public void Mod7_matches_operator(uint value)
-    {
-        value.Mod7().Should().Be(value % 7U);
-    }
-
     [Theory]
     [Trait("Category", "Fast")]
     [InlineData(0U)]
@@ -59,38 +37,5 @@ public class UIntExtensionsTests
     {
         value.Mod8().Should().Be(value % 8U);
     }
-
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0U)]
-    [InlineData(1U)]
-    [InlineData(1234567890U)]
-    [InlineData(uint.MaxValue)]
-    public void Mod10_matches_operator(uint value)
-    {
-        value.Mod10().Should().Be(value % 10U);
-    }
-
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0U)]
-    [InlineData(1U)]
-    [InlineData(1234567890U)]
-    [InlineData(uint.MaxValue)]
-    public void Mod11_matches_operator(uint value)
-    {
-        value.Mod11().Should().Be(value % 11U);
-    }
-
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0U)]
-    [InlineData(1U)]
-    [InlineData(1234567890U)]
-    [InlineData(uint.MaxValue)]
-    public void Mod128_matches_operator(uint value)
-    {
-        value.Mod128().Should().Be(value % 128U);
-    }
 }
 

PerfectNumbers.Core.Tests/ULongExtensionsTests.cs

@@ -21,66 +21,6 @@ public class ULongExtensionsTests
         ULongExtensions.Mod10(value).Should().Be(expected);
     }
 
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0UL)]
-    [InlineData(ulong.MaxValue)]
-    [InlineData(1234567890123456789UL)]
-    public void Mod3_matches_operator(ulong value)
-    {
-        value.Mod3().Should().Be(value % 3UL);
-    }
-
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0UL)]
-    [InlineData(ulong.MaxValue)]
-    [InlineData(1234567890123456789UL)]
-    public void Mod5_matches_operator(ulong value)
-    {
-        value.Mod5().Should().Be(value % 5UL);
-    }
-
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0UL)]
-    [InlineData(ulong.MaxValue)]
-    [InlineData(1234567890123456789UL)]
-    public void Mod6_matches_operator(ulong value)
-    {
-        value.Mod6().Should().Be(value % 6UL);
-    }
-
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0UL)]
-    [InlineData(ulong.MaxValue)]
-    [InlineData(1234567890123456789UL)]
-    public void Mod7_matches_operator(ulong value)
-    {
-        value.Mod7().Should().Be(value % 7UL);
-    }
-
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0UL)]
-    [InlineData(ulong.MaxValue)]
-    [InlineData(1234567890123456789UL)]
-    public void Mod8_matches_operator(ulong value)
-    {
-        value.Mod8().Should().Be(value % 8UL);
-    }
-
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0UL)]
-    [InlineData(ulong.MaxValue)]
-    [InlineData(1234567890123456789UL)]
-    public void Mod11_matches_operator(ulong value)
-    {
-        value.Mod11().Should().Be(value % 11UL);
-    }
-
     [Theory]
     [Trait("Category", "Fast")]
     [InlineData(0UL)]
@@ -111,22 +51,6 @@ public class ULongExtensionsTests
         step3.Should().Be(expected3);
     }
 
-    [Theory]
-    [Trait("Category", "Fast")]
-    [InlineData(0UL)]
-    [InlineData(1UL)]
-    [InlineData(1234567890123456789UL)]
-    [InlineData(ulong.MaxValue)]
-    public void Mod11_7_5_3_matches_operator(ulong value)
-    {
-        value.Mod11_7_5_3(out ulong mod11, out ulong mod7, out ulong mod5, out ulong mod3);
-
-        mod11.Should().Be(value % 11UL);
-        mod7.Should().Be(value % 7UL);
-        mod5.Should().Be(value % 5UL);
-        mod3.Should().Be(value % 3UL);
-    }
-
     [Theory]
     [Trait("Category", "Fast")]
     [InlineData(2UL, true)]

PerfectNumbers.Core/Cpu/MersenneNumberLucasLehmerCpuTester.cs

@@ -9,10 +9,10 @@ public class MersenneNumberLucasLehmerCpuTester
         // - If p ≡ 1 (mod 4) and p shares a factor with (p-1), reject fast.
         // - If p is divisible by divisors specific to numbers ending with 1 or 7, reject fast.
         if (
-            (exponent.Mod3() == 0UL && exponent != 3UL) ||
-            (exponent.Mod5() == 0UL && exponent != 5UL) ||
-            (exponent.Mod7() == 0UL && exponent != 7UL) ||
-            (exponent.Mod11() == 0UL && exponent != 11UL)
+            ((exponent % 3UL) == 0UL && exponent != 3UL) ||
+            ((exponent % 5UL) == 0UL && exponent != 5UL) ||
+            ((exponent % 7UL) == 0UL && exponent != 7UL) ||
+            ((exponent % 11UL) == 0UL && exponent != 11UL)
         )
 		{
 			return false;

PerfectNumbers.Core/Gpu/GpuKernelPool.cs

@@ -1,6 +1,5 @@
 using System.Collections.Concurrent;
 using System.Runtime.CompilerServices;
-using System.Threading;
 using ILGPU;
 using ILGPU.Runtime;
 using static PerfectNumbers.Core.Gpu.GpuContextPool;
@@ -200,8 +199,8 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
         ArrayView1D<uint, Stride1D.Dense> smallCycles)
     {
         ulong idx = (ulong)index.X;
-        ulong idxMod3 = idx.Mod3();
-        ulong idxMod5 = idx.Mod5();
+        ulong idxMod3 = idx % 3UL;
+        ulong idxMod5 = idx % 5UL;
         // residue automaton
         ulong step10 = (exponent.Mod10() << 1).Mod10();
         ulong r10 = q0m10 + (step10 * idx).Mod10();
@@ -217,7 +216,7 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
 			}
             else
             {
-                ulong step3 = (exponent.Mod3() << 1).Mod3();
+                ulong step3 = ((exponent % 3UL) << 1) % 3UL;
                 ulong r3 = q0m3 + (step3 * idxMod3); r3 -= (r3 >= 3UL) ? 3UL : 0UL;
                 if (r3 == 0UL)
                 {
@@ -225,7 +224,7 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
                 }
                 else
                 {
-                    ulong step5Loc = (exponent.Mod5() << 1).Mod5();
+                    ulong step5Loc = ((exponent % 5UL) << 1) % 5UL;
                     ulong r5 = q0m5 + (step5Loc * idxMod5); if (r5 >= 5UL) r5 -= 5UL;
                     if (r5 == 0UL)
                     {
@@ -360,8 +359,8 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
         ArrayView1D<ulong, Stride1D.Dense> smallPrimesPow2LastSeven)
     {
         ulong idx = (ulong)index.X;
-        ulong idxMod3 = idx.Mod3();
-        ulong idxMod5 = idx.Mod5();
+        ulong idxMod3 = idx % 3UL;
+        ulong idxMod5 = idx % 5UL;
         ulong r10 = ra.Q0M10 + (ra.Step10 * idx).Mod10(); r10 -= (r10 >= 10UL) ? 10UL : 0UL;
         bool shouldCheck = r10 != 5UL;
         if (shouldCheck)
@@ -493,8 +492,8 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
                 ResidueAutomatonArgs ra, ArrayView<int> found, ArrayView1D<uint, Stride1D.Dense> smallCycles)
     {
         ulong idx = (ulong)index.X;
-        ulong idxMod3 = idx.Mod3();
-        ulong idxMod5 = idx.Mod5();
+        ulong idxMod3 = idx % 3UL;
+        ulong idxMod5 = idx % 5UL;
         ulong r10 = ra.Q0M10 + (ra.Step10 * idx).Mod10(); r10 -= (r10 >= 10UL) ? 10UL : 0UL;
 		bool shouldCheck = r10 != 5UL;
 		if (shouldCheck)
@@ -579,8 +578,8 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
                 ResidueAutomatonArgs ra, ArrayView<int> found, ArrayView1D<uint, Stride1D.Dense> smallCycles)
     {
         ulong idx = (ulong)index.X;
-        ulong idxMod3 = idx.Mod3();
-        ulong idxMod5 = idx.Mod5();
+        ulong idxMod3 = idx % 3UL;
+        ulong idxMod5 = idx % 5UL;
         ulong r10 = ra.Q0M10 + (ra.Step10 * idx).Mod10(); r10 -= (r10 >= 10UL) ? 10UL : 0UL;
 		bool shouldCheck = r10 != 5UL;
 		if (shouldCheck)

PerfectNumbers.Core/Gpu/MersenneNumberIncrementalGpuTester.cs

@@ -1,6 +1,5 @@
 using System.Buffers;
 using System.Runtime.InteropServices;
-using ILGPU;
 using ILGPU.Runtime;
 
 namespace PerfectNumbers.Core.Gpu;
@@ -10,98 +9,95 @@ public class MersenneNumberIncrementalGpuTester(GpuKernelType kernelType, bool u
 	private readonly GpuKernelType _kernelType = kernelType;
 	private readonly bool _useGpuOrder = useGpuOrder;
 
-        public void Scan(ulong exponent, UInt128 twoP, bool lastIsSeven, UInt128 maxK, ref bool isPrime)
-        {
-                var gpuLease = GpuKernelPool.GetKernel(_useGpuOrder);
-                var execution = gpuLease.EnterExecutionScope();
-                var accelerator = gpuLease.Accelerator;
-                var stream = gpuLease.Stream;
-                int batchSize = GpuConstants.ScanBatchSize; // large batch improves GPU occupancy
-                UInt128 kStart = 1UL;
-                ulong divMul = (ulong)((((UInt128)1 << 64) - UInt128.One) / exponent) + 1UL;
-                byte last = lastIsSeven ? (byte)1 : (byte)0; // ILGPU kernels do not support bool parameters
+	public void Scan(ulong exponent, UInt128 twoP, bool lastIsSeven, UInt128 maxK, ref bool isPrime)
+	{
+		var gpuLease = GpuKernelPool.GetKernel(_useGpuOrder);
+		var execution = gpuLease.EnterExecutionScope();
+		var accelerator = gpuLease.Accelerator;
+		var stream = gpuLease.Stream;
+		int batchSize = GpuConstants.ScanBatchSize; // large batch improves GPU occupancy
+		UInt128 kStart = 1UL;
+		ulong divMul = (ulong)((((UInt128)1 << 64) - UInt128.One) / exponent) + 1UL;
+		byte last = lastIsSeven ? (byte)1 : (byte)0; // ILGPU kernels do not support bool parameters
 
-                var pow2Kernel = gpuLease.Pow2ModKernel;
-                var incKernel = gpuLease.IncrementalKernel;
-                ulong step10 = (exponent.Mod10() << 1).Mod10();
-                ulong step8 = ((exponent & 7UL) << 1) & 7UL;
-                ulong step3 = (exponent.Mod3() << 1).Mod3();
-                ulong step5 = (exponent.Mod5() << 1).Mod5();
-                GpuUInt128 twoPGpu = (GpuUInt128)twoP;
-                var smallCyclesView = GpuKernelPool.EnsureSmallCyclesOnDevice(accelerator);
-                ResiduePrimeViews primeViews = default;
-                if (_kernelType == GpuKernelType.Pow2Mod)
-                {
-                        primeViews = GpuKernelPool.EnsureSmallPrimesOnDevice(accelerator);
-                }
+		var pow2Kernel = gpuLease.Pow2ModKernel;
+		var incKernel = gpuLease.IncrementalKernel;
+		exponent.Mod10_8_5_3Steps(out ulong step10, out ulong step8, out ulong step5, out ulong step3);
+		GpuUInt128 twoPGpu = (GpuUInt128)twoP;
+		var smallCyclesView = GpuKernelPool.EnsureSmallCyclesOnDevice(accelerator);
+		ResiduePrimeViews primeViews = default;
+		if (_kernelType == GpuKernelType.Pow2Mod)
+		{
+			primeViews = GpuKernelPool.EnsureSmallPrimesOnDevice(accelerator);
+		}
 
-                var orderBuffer = accelerator.Allocate1D<ulong>(batchSize);
-                // Avoid giant stack allocations that can trigger StackOverflow when batchSize is large.
-                // Rent a reusable array from the shared pool instead.
-                ulong[] orderArray = ArrayPool<ulong>.Shared.Rent(batchSize);
-                UInt128 remaining;
-                int currentSize;
-                int i;
-                UInt128 q = UInt128.Zero;
-                try
-                {
-                        while (kStart <= maxK && Volatile.Read(ref isPrime))
-                        {
-                                remaining = maxK - kStart + UInt128.One;
-                                currentSize = remaining > (UInt128)batchSize ? batchSize : (int)remaining;
-                                Span<ulong> orders = orderArray.AsSpan(0, currentSize);
-                                // Precompute residue automaton bases for this batch
-                                UInt128 q0 = twoP * kStart + UInt128.One;
-                                if (_kernelType == GpuKernelType.Pow2Mod)
-                                {
-                                        q0.Mod10_8_5_3(out ulong q0m10, out ulong q0m8, out ulong q0m5, out ulong q0m3);
-                                        var kernelArgs = new ResidueAutomatonArgs(q0m10, step10, q0m8, step8, q0m3, step3, q0m5, step5);
-                                        pow2Kernel(stream, currentSize, exponent, twoPGpu, (GpuUInt128)kStart, last, divMul,
-                                                kernelArgs, orderBuffer.View, smallCyclesView, primeViews.LastOne, primeViews.LastSeven,
-                                                primeViews.LastOnePow2, primeViews.LastSevenPow2);
-                                }
-                                else
-                                {
-                                        q0.Mod10_8_5_3(out ulong q0m10, out ulong q0m8, out ulong q0m5, out ulong q0m3);
-                                        incKernel(stream, currentSize, exponent, twoPGpu, (GpuUInt128)kStart, last, divMul,
-                                                q0m10, q0m8, q0m3, q0m5, orderBuffer.View, smallCyclesView);
-                                }
+		var orderBuffer = accelerator.Allocate1D<ulong>(batchSize);
+		// Avoid giant stack allocations that can trigger StackOverflow when batchSize is large.
+		// Rent a reusable array from the shared pool instead.
+		ulong[] orderArray = ArrayPool<ulong>.Shared.Rent(batchSize);
+		UInt128 remaining;
+		int currentSize;
+		int i;
+		UInt128 q = UInt128.Zero;
+		try
+		{
+			while (kStart <= maxK && Volatile.Read(ref isPrime))
+			{
+				remaining = maxK - kStart + UInt128.One;
+				currentSize = remaining > (UInt128)batchSize ? batchSize : (int)remaining;
+				Span<ulong> orders = orderArray.AsSpan(0, currentSize);
+				// Precompute residue automaton bases for this batch
+				UInt128 q0 = twoP * kStart + UInt128.One;
+				if (_kernelType == GpuKernelType.Pow2Mod)
+				{
+					q0.Mod10_8_5_3(out ulong q0m10, out ulong q0m8, out ulong q0m5, out ulong q0m3);
+					var kernelArgs = new ResidueAutomatonArgs(q0m10, step10, q0m8, step8, q0m3, step3, q0m5, step5);
+					pow2Kernel(stream, currentSize, exponent, twoPGpu, (GpuUInt128)kStart, last, divMul,
+							kernelArgs, orderBuffer.View, smallCyclesView, primeViews.LastOne, primeViews.LastSeven,
+							primeViews.LastOnePow2, primeViews.LastSevenPow2);
+				}
+				else
+				{
+					q0.Mod10_8_5_3(out ulong q0m10, out ulong q0m8, out ulong q0m5, out ulong q0m3);
+					incKernel(stream, currentSize, exponent, twoPGpu, (GpuUInt128)kStart, last, divMul,
+							q0m10, q0m8, q0m3, q0m5, orderBuffer.View, smallCyclesView);
+				}
 
-                                stream.Synchronize();
-                                orderBuffer.View.CopyToCPU(ref MemoryMarshal.GetReference(orders), currentSize);
-                                if (_kernelType == GpuKernelType.Pow2Mod)
-                                {
-                                        for (i = 0; i < currentSize; i++)
-                                        {
-                                                if (orders[i] != 0UL)
-                                                {
-                                                        Volatile.Write(ref isPrime, false);
-                                                        break;
-                                                }
-                                        }
-                                }
-                                else
-                                {
-                                        q = twoP * kStart + UInt128.One;
-                                        for (i = 0; i < currentSize && Volatile.Read(ref isPrime); i++, q += twoP)
-                                        {
-                                                if (orders[i] != 0UL && q.IsPrimeCandidate())
-                                                {
-                                                        Volatile.Write(ref isPrime, false);
-                                                }
-                                        }
-                                }
+				stream.Synchronize();
+				orderBuffer.View.CopyToCPU(ref MemoryMarshal.GetReference(orders), currentSize);
+				if (_kernelType == GpuKernelType.Pow2Mod)
+				{
+					for (i = 0; i < currentSize; i++)
+					{
+						if (orders[i] != 0UL)
+						{
+							Volatile.Write(ref isPrime, false);
+							break;
+						}
+					}
+				}
+				else
+				{
+					q = twoP * kStart + UInt128.One;
+					for (i = 0; i < currentSize && Volatile.Read(ref isPrime); i++, q += twoP)
+					{
+						if (orders[i] != 0UL && q.IsPrimeCandidate())
+						{
+							Volatile.Write(ref isPrime, false);
+						}
+					}
+				}
 
-                                kStart += (UInt128)currentSize;
-                        }
-                }
-                finally
-                {
-                        ArrayPool<ulong>.Shared.Return(orderArray);
-                        orderBuffer.Dispose();
-                        execution.Dispose();
-                        gpuLease.Dispose();
-                }
+				kStart += (UInt128)currentSize;
+			}
+		}
+		finally
+		{
+			ArrayPool<ulong>.Shared.Return(orderArray);
+			orderBuffer.Dispose();
+			execution.Dispose();
+			gpuLease.Dispose();
+		}
 
-        }
+	}
 }

PerfectNumbers.Core/Gpu/MersenneNumberLucasLehmerGpuTester.cs

@@ -51,7 +51,7 @@ public class MersenneNumberLucasLehmerGpuTester
         // Early rejections aligned with incremental/order sieves, but safe for small p:
         // - If 3 | p and p != 3, then 7 | M_p -> composite.
         // - If p ≡ 1 (mod 4) and p shares a factor with (p-1), reject fast.
-        if (exponent.Mod3() == 0UL && exponent != 3UL)
+        if ((exponent % 3UL) == 0UL && exponent != 3UL)
         {
             return false;
         }

PerfectNumbers.Core/Gpu/MersenneNumberOrderGpuTester.cs

@@ -25,12 +25,7 @@ public class MersenneNumberOrderGpuTester(GpuKernelType kernelType, bool useGpuO
 		};
 
 		var foundBuffer = accelerator.Allocate1D<int>(1);
-		UInt128 exponent128 = exponent;
-		exponent128.Mod10_8_5_3(out ulong exponentMod10, out ulong exponentMod8, out ulong exponentMod5, out ulong exponentMod3);
-            ulong step10 = (exponentMod10 << 1).Mod10();
-                ulong step8 = (exponentMod8 << 1) & 7UL;
-                ulong step3 = (exponentMod3 << 1).Mod3();
-                ulong step5 = (exponentMod5 << 1).Mod5();
+		exponent.Mod10_8_5_3Steps(out ulong step10, out ulong step8, out ulong step5, out ulong step3);
 		try
 		{
 			UInt128 remaining;

PerfectNumbers.Core/Gpu/MersenneNumberResidueGpuTester.cs

@@ -24,7 +24,11 @@ public class MersenneNumberResidueGpuTester(bool useGpuOrder)
 		UInt128 kStart = 1UL;
 		byte last = lastIsSeven ? (byte)1 : (byte)0;
 		var kernel = gpuLease.Pow2ModKernel;
-                exponent.Mod10_8_5_3Steps(out ulong step10, out ulong step8, out ulong step5, out ulong step3);
+		ulong step3 = exponent % 3UL,
+			  step5 = exponent % 5UL,
+			  step8 = exponent % 8UL,
+			  step10 = exponent.Mod10();
+
 		GpuUInt128 twoPGpu = (GpuUInt128)twoP;
 
 		var orderBuffer = accelerator.Allocate1D<ulong>(batchSize);

PerfectNumbers.Core/MersenneDivisorCycles.cs

@@ -85,7 +85,7 @@ public class MersenneDivisorCycles
 				}
 			}
 		}
-		
+
 		// Binary search for divisor in sorted _table
 		int mid, right, left = 0;
 		ulong d;
@@ -189,7 +189,7 @@ public class MersenneDivisorCycles
 						for (int i = 0; i < localCycleIndex; i++)
 						{
 							(d, cycle) = localCycles[i];
-                                                    if (d.Mod3() == 0UL || d.Mod5() == 0UL || d.Mod7() == 0UL || d.Mod11() == 0UL)
+							if ((d % 3UL) == 0UL || (d % 5UL) == 0UL || (d % 7UL) == 0UL || (d % 11UL) == 0UL)
 								continue;
 
 							writer.Write(d);
@@ -222,15 +222,15 @@ public class MersenneDivisorCycles
 		int count = (int)Math.Min(batchSizeUL, maxDivisor), i, idx;
 		ulong[] divisors, outCycles, validDivisors;
 
-                divisors = pool.Rent(count);
-                outCycles = pool.Rent(count);
-                var lease = GpuKernelPool.GetKernel(useGpuOrder: true);
-                var accelerator = lease.Accelerator;
-                var stream = accelerator.CreateStream();
-                var kernel = accelerator.LoadAutoGroupedStreamKernel<
-                        Index1D,
-                        ArrayView1D<ulong, Stride1D.Dense>,
-                        ArrayView1D<ulong, Stride1D.Dense>>(GpuDivisorCycleKernel);
+		divisors = pool.Rent(count);
+		outCycles = pool.Rent(count);
+		var lease = GpuKernelPool.GetKernel(useGpuOrder: true);
+		var accelerator = lease.Accelerator;
+		var stream = accelerator.CreateStream();
+		var kernel = accelerator.LoadAutoGroupedStreamKernel<
+				Index1D,
+				ArrayView1D<ulong, Stride1D.Dense>,
+				ArrayView1D<ulong, Stride1D.Dense>>(GpuDivisorCycleKernel);
 
 
 		using Stream outputStream = new FileStream(path, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.Read, BufferSize10M, useAsync: true);
@@ -249,7 +249,7 @@ public class MersenneDivisorCycles
 		{
 			while (skipCount > 0L && start <= maxDivisor)
 			{
-                            if ((start & 1UL) == 0UL || start.Mod3() == 0UL || start.Mod5() == 0UL || start.Mod7() == 0UL || start.Mod11() == 0UL)
+				if ((start & 1UL) == 0UL || (start % 3UL) == 0UL || (start % 5UL) == 0UL || (start % 7UL) == 0UL || (start % 11UL) == 0UL)
 				{
 					start++;
 					continue;
@@ -280,10 +280,10 @@ public class MersenneDivisorCycles
 				var bufferDiv = accelerator.Allocate1D(validDivisors);
 				var bufferCycle = accelerator.Allocate1D<ulong>(idx);
 
-                                kernel(
-                                        idx,
-                                        bufferDiv.View,
-                                        bufferCycle.View);
+				kernel(
+						idx,
+						bufferDiv.View,
+						bufferCycle.View);
 
 				accelerator.Synchronize();
 
@@ -296,7 +296,7 @@ public class MersenneDivisorCycles
 				{
 					d = divisors[i];
 
-                                    if (d.Mod3() == 0UL || d.Mod5() == 0UL || d.Mod7() == 0UL || d.Mod11() == 0UL)
+					if ((d % 3UL) == 0UL || (d % 5UL) == 0UL || (d % 7UL) == 0UL || (d % 11UL) == 0UL)
 						continue;
 
 					writer.Write(d);
@@ -308,16 +308,16 @@ public class MersenneDivisorCycles
 				start = end + 1UL;
 			}
 		}
-                finally
-                {
-                        pool.Return(divisors, clearArray: false);
-                        pool.Return(outCycles, clearArray: false);
-                }
+		finally
+		{
+			pool.Return(divisors, clearArray: false);
+			pool.Return(outCycles, clearArray: false);
+		}
 
-                stream.Dispose();
-                lease.Dispose();
+		stream.Dispose();
+		lease.Dispose();
 
-        }
+	}
 
 	const byte ByteZero = 0;
 	const byte ByteOne = 1;

PerfectNumbers.Core/MersenneNumberTester.cs

@@ -203,7 +203,7 @@ public sealed class MersenneNumberTester(
     {
         // Safe early rejections using known orders for tiny primes:
         // 7 | M_p iff 3 | p. Avoid rejecting p == 3 where M_3 == 7 is prime.
-        if (exponent.Mod3() == 0UL && exponent != 3UL)
+        if ((exponent % 3UL) == 0UL && exponent != 3UL)
         {
             return false;
         }

PerfectNumbers.Core/PrimeTester.cs

@@ -53,7 +53,7 @@ public sealed class PrimeTester(bool useInternal = false)
         {
             result = false;
         }
-        else if (n > 5UL && n.Mod5() == 0UL)
+        else if (n > 5UL && (n % 5UL) == 0UL)
         {
             result = false;
         }
@@ -260,7 +260,7 @@ public sealed class PrimeTester(bool useInternal = false)
             return;
         }
 
-        if ((n & 1UL) == 0UL || (n > 5UL && n.Mod5() == 0UL))
+        if ((n & 1UL) == 0UL || (n > 5UL && (n % 5UL) == 0UL))
         {
             results[index] = 0;
             return;

PerfectNumbers.Core/UInt128Extensions.cs

@@ -96,109 +96,147 @@ public static class UInt128Extensions
 	}
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static bool IsPrimeCandidate(this UInt128 n)
-        {
-                UInt128 p;
+	public static bool IsPrimeCandidate(this UInt128 n)
+	{
+		UInt128 p, zero = UInt128.Zero;
 
-                uint[] smallPrimes = PrimesGenerator.SmallPrimes;
-                ulong[] smallPrimesPow2 = PrimesGenerator.SmallPrimesPow2;
-                ulong i, smallPrimesCount = (ulong)smallPrimes.Length;
-                for (i = 0UL; i < smallPrimesCount; i++)
-                {
-                        p = smallPrimes[i];
-                        if (smallPrimesPow2[i] > n)
-                        {
-                                break;
-                        }
+		uint[] smallPrimes = PrimesGenerator.SmallPrimes;
+		ulong[] smallPrimesPow2 = PrimesGenerator.SmallPrimesPow2;
+		ulong i, smallPrimesCount = (ulong)smallPrimes.Length;
+		for (i = 0UL; i < smallPrimesCount; i++)
+		{
+			if (smallPrimesPow2[i] > n)
+			{
+				break;
+			}
 
-                        if (n % p == UInt128.Zero)
-                        {
-                                return n == p;
-                        }
-                }
+			p = smallPrimes[i];
+			if (n % p == zero)
+			{
+				return n == p;
+			}
+		}
 
 		return true;
 	}
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Mod10_8_5_3(this UInt128 value, out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3)
-        {
-                UInt128 temp = UInt128.Zero;
-                uint byteSum = 0U;
-                byte current = 0;
-                uint accumulator = 0U;
-
-                temp = value;
-                do
-                {
-                        current = (byte)temp;
-                        byteSum += current;
-                        temp >>= 8;
-                }
-                while (temp != UInt128.Zero);
-
-                mod8 = (ulong)value & 7UL;
-
-                accumulator = byteSum.Mod5();
-                mod5 = accumulator;
-                mod10 = (mod8 & 1UL) == 0UL
-                                ? accumulator switch
-                                {
-                                        0U => 0UL,
-                                        1U => 6UL,
-                                        2U => 2UL,
-                                        3U => 8UL,
-                                        _ => 4UL,
-                                }
-                                : accumulator switch
-                                {
-                                        0U => 5UL,
-                                        1U => 1UL,
-                                        2U => 7UL,
-                                        3U => 3UL,
-                                        _ => 9UL,
-                                };
-
-                // Reusing accumulator to hold the mod 3 reduction now that the mod 5 value has been stored.
-                accumulator = byteSum.Mod3();
-                mod3 = accumulator;
-        }
+	public static ulong Mod3(this UInt128 value)
+	{
+		ulong remainder = ((ulong)value) % 3UL + ((ulong)(value >> 64)) % 3UL;
+		return remainder >= 3UL ? remainder - 3UL : remainder;
+	}
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
-	public static UInt128 Pow(this UInt128 value, ulong exponent)
+	public static ulong Mod5(this UInt128 value)
 	{
-		UInt128 result = UInt128.One;
-		UInt128 baseValue = value;
+		ulong remainder = (((ulong)value) % 5UL) + (((ulong)(value >> 64)) % 5UL);
+		return remainder >= 5UL ? remainder - 5UL : remainder;
+	}
 
-		while (exponent != 0UL)
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod6(this UInt128 value) => ((value.Mod3() << 1) | ((ulong)value & 1UL)) switch
+	{
+		0UL => 0UL,
+		1UL => 3UL,
+		2UL => 4UL,
+		3UL => 1UL,
+		4UL => 2UL,
+		_ => 5UL,
+	};
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod7(this UInt128 value)
+	{
+		ulong remainder = (((ulong)value) % 7UL) + (((ulong)(value >> 64)) % 7UL) << 1;
+		while (remainder >= 7UL)
 		{
-			if ((exponent & 1UL) != 0UL)
-			{
-				result *= baseValue;
-			}
-
-			baseValue *= baseValue;
-			exponent >>= 1;
+			remainder -= 7UL;
 		}
 
-		return result;
+		return remainder;
 	}
 
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod8(this UInt128 value) => (ulong)value & 7UL;
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod10(this UInt128 value128)
+	{
+		// Split and fold under mod 10: 2^64 ≡ 6 (mod 10)
+		ulong value = (ulong)value128;
+		return ((value % 10UL) + ((value >> 64) % 10UL) * 6UL) % 10UL;
+	}
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static void Mod10_8_5_3(this UInt128 value, out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3)
+	{
+		byte current;
+		uint byteSum = 0U;
+		mod8 = (ulong)value & 7UL;
+		UInt128 zero = UInt128.Zero;
+		do
+		{
+			current = (byte)value;
+			byteSum += current;
+			value >>= 8;
+		}
+		while (value != zero);
+
+		mod5 = byteSum.Mod5();
+		mod10 = (mod8 & 1UL) == 0UL
+						? mod5 switch
+						{
+							0U => 0UL,
+							1U => 6UL,
+							2U => 2UL,
+							3U => 8UL,
+							_ => 4UL,
+						}
+						: mod5 switch
+						{
+							0U => 5UL,
+							1U => 1UL,
+							2U => 7UL,
+							3U => 3UL,
+							_ => 9UL,
+						};
+
+		mod3 = byteSum % 3U;
+	}
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod11(this UInt128 value)
+	{
+		ulong remainder = (((ulong)value) % 11UL) + (((ulong)(value >> 64)) % 11UL) * 5UL;
+		while (remainder >= 11UL)
+		{
+			remainder -= 11UL;
+		}
+
+		return remainder;
+	}
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod128(this UInt128 value) => (ulong)value & 127UL;
+
+
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
 	public static UInt128 ModPow(this UInt128 value, UInt128 exponent, UInt128 modulus)
 	{
-                UInt128 zero = UInt128.Zero;
-                UInt128 result = UInt128.One;
-                UInt128 baseValue = value % modulus;
+		UInt128 zero = UInt128.Zero;
+		UInt128 one = UInt128.One;
+		UInt128 result = UInt128.One;
+		value %= modulus;
 
-                while (exponent != zero)
-                {
-                        if ((exponent & UInt128.One) != zero)
-                        {
-                                result = MulMod(result, baseValue, modulus);
-                        }
+		while (exponent != zero)
+		{
+			if ((exponent & one) != zero)
+			{
+				result = MulMod(result, value, modulus);
+			}
 
-			baseValue = MulMod(baseValue, baseValue, modulus);
+			value = MulMod(value, value, modulus);
 			exponent >>= 1;
 		}
 
@@ -206,87 +244,8 @@ public static class UInt128Extensions
 	}
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod10(this UInt128 value)
-        {
-                UInt128 zero = UInt128.Zero;
-                if (value == zero)
-                        return 0UL;
-
-                ulong result = (ulong)value;
-                UInt128 high = value >> 64;
-
-                while (high != zero)
-                {
-                        // 2^64 ≡ 6 (mod 10)
-                        result = (result + (ulong)high * 6UL) % 10UL;
-                        high >>= 64;
-                }
-
-                return result % 10UL;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod8(this UInt128 value) => (ulong)value & 7UL;
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod3(this UInt128 value)
-        {
-                ulong remainder = ((ulong)value % 3UL) + ((ulong)(value >> 64) % 3UL);
-                return remainder >= 3UL ? remainder - 3UL : remainder;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod5(this UInt128 value)
-        {
-                ulong remainder = ((ulong)value % 5UL) + ((ulong)(value >> 64) % 5UL);
-                return remainder >= 5UL ? remainder - 5UL : remainder;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod6(this UInt128 value)
-        {
-                return ((value.Mod3() << 1) | ((ulong)value & 1UL)) switch
-                {
-                        0UL => 0UL,
-                        1UL => 3UL,
-                        2UL => 4UL,
-                        3UL => 1UL,
-                        4UL => 2UL,
-                        _ => 5UL,
-                };
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod7(this UInt128 value)
-        {
-                ulong remainder = ((ulong)value % 7UL) + ((ulong)(value >> 64) % 7UL) * 2UL;
-                while (remainder >= 7UL)
-                {
-                        remainder -= 7UL;
-                }
-
-                return remainder;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod11(this UInt128 value)
-        {
-                ulong remainder = ((ulong)value % 11UL) + ((ulong)(value >> 64) % 11UL) * 5UL;
-                while (remainder >= 11UL)
-                {
-                        remainder -= 11UL;
-                }
-
-                return remainder;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod128(this UInt128 value) => (ulong)value & 127UL;
-
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static UInt128 Mul64(this UInt128 a, UInt128 b)
-        {
+	public static UInt128 Mul64(this UInt128 a, UInt128 b)
+	{
 		ulong aLow = (ulong)a;
 		ulong bLow = (ulong)b;
 		return ((UInt128)(aLow * (ulong)(b >> 64) + aLow.MulHigh(bLow)) << 64) | (aLow * bLow);
@@ -295,15 +254,16 @@ public static class UInt128Extensions
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
 	public static UInt128 MulMod(this UInt128 a, UInt128 b, UInt128 modulus)
 	{
-                UInt128 zero = UInt128.Zero;
-                UInt128 result = UInt128.Zero;
+		UInt128 one = UInt128.One,
+				result = UInt128.Zero,
+				zero = UInt128.Zero;
 
-                while (b != zero)
-                {
-                        if ((b & UInt128.One) != zero)
-                        {
-                                result += a;
-                                if (result >= modulus)
+		while (b != zero)
+		{
+			if ((b & one) != zero)
+			{
+				result += a;
+				if (result >= modulus)
 				{
 					result -= modulus;
 				}
@@ -320,4 +280,22 @@ public static class UInt128Extensions
 
 		return result;
 	}
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static UInt128 Pow(this UInt128 value, ulong exponent)
+	{
+		UInt128 result = UInt128.One;
+		while (exponent != 0UL)
+		{
+			if ((exponent & 1UL) != 0UL)
+			{
+				result *= value;
+			}
+
+			value *= value;
+			exponent >>= 1;
+		}
+
+		return result;
+	}
 }

PerfectNumbers.Core/UIntExtensions.cs

@@ -4,28 +4,16 @@ namespace PerfectNumbers.Core;
 
 public static class UIntExtensions
 {
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static uint Mod3(this uint value) => value % 3U;
+	private const ulong Mod3Mask = 0xAAAAAAABUL;
+	public const ulong Mod5Mask = 0xCCCCCCCDUL;
 
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static uint Mod5(this uint value) => value % 5U;
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static uint Mod3(uint value) => value - (uint)((value * Mod3Mask) >> 33) * 3U;
 
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static uint Mod6(this uint value) => value % 6U;
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static uint Mod5(this uint value) => value - (uint)((value * Mod5Mask) >> 34) * 5U;
 
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static uint Mod7(this uint value) => value % 7U;
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static uint Mod8(this uint value) => value & 7U;
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static uint Mod10(this uint value) => value % 10U;
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static uint Mod11(this uint value) => value % 11U;
-
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static uint Mod128(this uint value) => value & 127U;
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static uint Mod8(this uint value) => value & 7U;
 }
 

PerfectNumbers.Core/ULongExtensions.cs

@@ -48,196 +48,110 @@ public static class ULongExtensions
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
 	public static ulong FastDiv64(this ulong value, ulong divisor, ulong mul)
 	{
-		ulong q = value.MulHigh(mul);
-		if ((UInt128)value - q.Mul64(divisor) >= divisor)
+		mul = value.MulHigh(mul);
+		if ((UInt128)value - mul.Mul64(divisor) >= divisor)
 		{
-			q++;
+			mul++;
 		}
 
-		return q;
+		return mul;
 	}
 
-        private static readonly byte[] Mod7ByteCoefficients = { 1, 4, 2, 1, 4, 2, 1, 4 };
-        private static readonly byte[] Mod11ByteCoefficients = { 1, 3, 9, 5, 4, 1, 3, 9 };
+	public const ulong WordBitMask = 0xFFFFUL;
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Mod10_8_5_3(this ulong value, out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3)
-        {
-                ulong temp = 0UL;
-                uint byteSum = 0U;
-                byte current = 0;
-                uint accumulator = 0U;
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static bool IsPrimeCandidate(this ulong n)
+	{
+		int i = 0;
+		uint[] smallPrimes = PrimesGenerator.SmallPrimes;
+		ulong[] smallPrimesPow2 = PrimesGenerator.SmallPrimesPow2;
+		int len = smallPrimes.Length;
+		ulong p;
+		for (; i < len; i++)
+		{
+			if (smallPrimesPow2[i] > n)
+			{
+				break;
+			}
 
-                temp = value;
-                do
-                {
-                        current = (byte)temp;
-                        byteSum += current;
-                        temp >>= 8;
-                }
-                while (temp != 0UL);
+			p = smallPrimes[i];
+			if ((n % p) == 0UL)
+			{
+				return n == p;
+			}
+		}
 
-                mod8 = value & 7UL;
+		return true;
+	}
 
-                accumulator = byteSum.Mod5();
-                mod5 = accumulator;
-                mod10 = (mod8 & 1UL) == 0UL
-                                ? accumulator switch
-                                {
-                                        0U => 0UL,
-                                        1U => 6UL,
-                                        2U => 2UL,
-                                        3U => 8UL,
-                                        _ => 4UL,
-                                }
-                                : accumulator switch
-                                {
-                                        0U => 5UL,
-                                        1U => 1UL,
-                                        2U => 7UL,
-                                        3U => 3UL,
-                                        _ => 9UL,
-                                };
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod10(this ulong value) => (value & 1UL) == 0UL
+			? value % 5UL switch
+			{
+				0UL => 0UL,
+				1UL => 6UL,
+				2UL => 2UL,
+				3UL => 8UL,
+				_ => 4UL,
+			}
+			: value % 5UL switch
+			{
+				0UL => 5UL,
+				1UL => 1UL,
+				2UL => 7UL,
+				3UL => 3UL,
+				_ => 9UL,
+			};
 
-                // Reusing accumulator to hold the mod 3 reduction now that the mod 5 value has been stored.
-                accumulator = byteSum.Mod3();
-                mod3 = accumulator;
-        }
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong Mod128(this ulong value) => value & 127UL;
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Mod11_7_5_3(this ulong value, out ulong mod11, out ulong mod7, out ulong mod5, out ulong mod3)
-        {
-                uint mod3Accumulator = 0U;
-                uint mod5Accumulator = 0U;
-                uint mod7Accumulator = 0U;
-                uint mod11Accumulator = 0U;
-                ulong temp = 0UL;
-                int index = 0;
-                byte current = 0;
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static void Mod10_8_5_3(this ulong value, out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3)
+	{
+		mod8 = value & 7UL;
 
-                temp = value;
-                do
-                {
-                        current = (byte)temp;
-                        mod3Accumulator += current;
-                        mod5Accumulator += current;
-                        mod7Accumulator += (uint)(current * Mod7ByteCoefficients[index]);
-                        mod11Accumulator += (uint)(current * Mod11ByteCoefficients[index]);
+		byte current;
+		uint byteSum = 0U;
+		do
+		{
+			current = (byte)value;
+			byteSum += current;
+			value >>= 8;
+		}
+		while (value != 0UL);
 
-                        temp >>= 8;
-                        index++;
-                }
-                while (temp != 0UL);
+		mod3 = byteSum % 3U;
+		mod5 = byteSum % 5U;
+		mod10 = (mod8 & 1UL) == 0UL
+						? mod5 switch
+						{
+							0UL => 0UL,
+							1UL => 6UL,
+							2UL => 2UL,
+							3UL => 8UL,
+							_ => 4UL,
+						}
+						: mod5 switch
+						{
+							0UL => 5UL,
+							1UL => 1UL,
+							2UL => 7UL,
+							3UL => 3UL,
+							_ => 9UL,
+						};
+	}
 
-                // Reusing mod3Accumulator to store the reduced mod 3 remainder before exposing it.
-                mod3Accumulator = mod3Accumulator.Mod3();
-                // Reusing mod5Accumulator to store the reduced mod 5 remainder before exposing it.
-                mod5Accumulator = mod5Accumulator.Mod5();
-                // Reusing mod7Accumulator to store the reduced mod 7 remainder before exposing it.
-                mod7Accumulator = (uint)ReduceMod7(mod7Accumulator);
-                // Reusing mod11Accumulator to store the reduced mod 11 remainder before exposing it.
-                mod11Accumulator = (uint)ReduceMod11(mod11Accumulator);
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static void Mod10_8_5_3Steps(this ulong value, out ulong step10, out ulong step8, out ulong step5, out ulong step3)
+	{
+		value.Mod10_8_5_3(out step10, out step8, out step5, out step3);
 
-                mod3 = mod3Accumulator;
-                mod5 = mod5Accumulator;
-                mod7 = mod7Accumulator;
-                mod11 = mod11Accumulator;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static void Mod10_8_5_3Steps(this ulong value, out ulong step10, out ulong step8, out ulong step5, out ulong step3)
-        {
-                ulong mod10 = 0UL;
-                ulong mod8 = 0UL;
-                ulong mod5 = 0UL;
-                ulong mod3 = 0UL;
-
-                value.Mod10_8_5_3(out mod10, out mod8, out mod5, out mod3);
-
-                step10 = (mod10 << 1).Mod10();
-                step8 = ((mod8 << 1) & 7UL);
-                step5 = (mod5 << 1).Mod5();
-                step3 = (mod3 << 1).Mod3();
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static bool IsPrimeCandidate(this ulong n)
-        {
-                int i = 0;
-                ulong p = 0UL;
-                uint[] smallPrimes = PrimesGenerator.SmallPrimes;
-                ulong[] smallPrimesPow2 = PrimesGenerator.SmallPrimesPow2;
-                int len = smallPrimes.Length;
-                for (; i < len; i++)
-                {
-                        if (smallPrimesPow2[i] > n)
-                        {
-                                break;
-                        }
-
-                        p = smallPrimes[i];
-                        if ((n % p) == 0UL)
-                        {
-                                return n == p;
-                        }
-                }
-
-                return true;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod10(this ulong value) => value % 10UL;
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod8(this ulong value) => value & 7UL;
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod3(this ulong value) => value % 3UL;
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod5(this ulong value) => value % 5UL;
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod6(this ulong value) => value % 6UL;
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod7(this ulong value) => value % 7UL;
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod11(this ulong value) => value % 11UL;
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong Mod128(this ulong value) => value & 127UL;
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static ulong ReduceMod7(uint value)
-        {
-                while (value >= 7U)
-                {
-                        value = (value >> 3) + (value & 7U);
-                        if (value >= 7U && value < 14U)
-                        {
-                                value -= 7U;
-                        }
-                }
-
-                return value;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static ulong ReduceMod11(uint value)
-        {
-                while (value >= 11U)
-                {
-                        value = (value & 15U) + ((value >> 4) * 5U);
-                        if (value >= 11U && value < 22U)
-                        {
-                                value -= 11U;
-                        }
-                }
-
-                return value;
-        }
+		step10 = (step10 << 1).Mod10();
+		step8 = (step8 << 1) & 7UL;
+		step5 = (step5 << 1) % 5UL;
+		step3 = (step3 << 1) % 3UL;
+	}
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
 	public static UInt128 Mul64(this ulong a, ulong b) => ((UInt128)a.MulHigh(b) << 64) | (UInt128)(a * b);
@@ -252,384 +166,326 @@ public static class ULongExtensions
 
 		ulong w1 = xLow * yHigh;
 		ulong w2 = xHigh * yLow;
-		ulong carry =
-			(((xLow * yLow) >> 32) +
-			(uint)w1 +
-			(uint)w2) >> 32;
 
-		return (xHigh * yHigh) + (w1 >> 32) + (w2 >> 32) + carry;
+		return (xHigh * yHigh) + (w1 >> 32) + (w2 >> 32) +
+			(
+				((xLow * yLow) >> 32) +
+				(uint)w1 +
+				(uint)w2
+			) >> 32;
 	}
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
 	public static ulong ModPow64(this ulong value, ulong exponent, ulong modulus)
 	{
 		ulong result = 1UL;
-		ulong baseValue = value % modulus;
+		value %= modulus;
 
 		while (exponent != 0UL)
 		{
 			if ((exponent & 1UL) != 0UL)
 			{
-				result = MulMod64(result, baseValue, modulus);
+				result = MulMod64(result, value, modulus);
 			}
 
-			baseValue = MulMod64(baseValue, baseValue, modulus);
+			value = MulMod64(value, value, modulus);
 			exponent >>= 1;
 		}
 
 		return result;
 	}
 
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static ulong MulMod64(this ulong a, ulong b, ulong modulus)
-        {
-                if (modulus <= 1UL)
-                {
-                        return 0UL;
-                }
-
-                if (TryGetMersenneExponent(modulus, out int exponent))
-                {
-                        return MulModMersenne(a, b, modulus, exponent);
-                }
-
-                return (ulong)(((UInt128)a * b) % modulus);
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static bool TryGetMersenneExponent(ulong modulus, out int exponent)
-        {
-                if (modulus == 0UL)
-                {
-                        exponent = 0;
-                        return false;
-                }
-
-                ulong plusOne = modulus + 1UL;
-                if (plusOne == 0UL)
-                {
-                        exponent = 64;
-                        return true;
-                }
-
-                if ((plusOne & (plusOne - 1UL)) != 0UL)
-                {
-                        exponent = 0;
-                        return false;
-                }
-
-                exponent = BitOperations.TrailingZeroCount(plusOne);
-                return true;
-        }
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private static ulong MulModMersenne(ulong a, ulong b, ulong modulus, int exponent)
-        {
-                UInt128 mask = (UInt128)modulus;
-                UInt128 product = (UInt128)a * b;
-                UInt128 folded = (product & mask) + (product >> exponent);
-
-                while (folded > mask)
-                {
-                        folded = (folded & mask) + (folded >> exponent);
-                }
-
-                ulong result = (ulong)folded;
-                if (result >= modulus)
-                {
-                        result -= modulus;
-                }
-
-                return result;
-        }
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static ulong MulMod64(this ulong a, ulong b, ulong modulus) => (ulong)(UInt128)(((a % modulus) * (b % modulus)) % modulus);
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static UInt128 PowMod(this ulong exponent, UInt128 modulus)
-        {
-                UInt128 result = UInt128.One;
-                ulong exponentLoopIndex = 0UL;
+	public static UInt128 PowMod(this ulong exponent, UInt128 modulus)
+	{
+		UInt128 result = UInt128.One;
+		ulong exponentLoopIndex = 0UL;
 
-                // Return 1 because 2^0 = 1
-                if (exponent == 0UL)
-                        return result;
+		// Return 1 because 2^0 = 1
+		if (exponent == 0UL)
+			return result;
 
-                // Any number mod 1 is 0
-                if (modulus == UInt128.One)
-                        return UInt128.Zero;
+		// Any number mod 1 is 0
+		if (modulus == UInt128.One)
+			return UInt128.Zero;
 
-                // For small exponents, do classic method
-                if (exponent < 64 || modulus < 4)
-                {
-                        for (; exponentLoopIndex < exponent; exponentLoopIndex++)
-                        {
-                                result <<= 1;
-                                if (result >= modulus)
-                                        result -= modulus;
-                        }
+		// For small exponents, do classic method
+		if (exponent < 64 || modulus < 4)
+		{
+			for (; exponentLoopIndex < exponent; exponentLoopIndex++)
+			{
+				result <<= 1;
+				if (result >= modulus)
+					result -= modulus;
+			}
 
-                        return result;
-                }
+			return result;
+		}
 
-                // Special case: if modulus is a power of two, use bitmasking for efficiency and correctness
-                if ((modulus & (modulus - 1)) == 0)
-                {
-                        result = UInt128.One << (int)(exponent & 127);
-                        return result & (modulus - 1);
-                }
+		// Special case: if modulus is a power of two, use bitmasking for efficiency and correctness
+		if ((modulus & (modulus - 1)) == 0)
+		{
+			result = UInt128.One << (int)(exponent & 127);
+			return result & (modulus - 1);
+		}
 
-                // Reusing exponentLoopIndex to iterate again over the exponent range for the general-case accumulation.
-                exponentLoopIndex = 0UL;
-                // Reusing result after resetting it for the general modulus accumulation phase.
-                result = UInt128.One;
-                for (; exponentLoopIndex < exponent; exponentLoopIndex++)
-                {
-                        result <<= 1;
-                        if (result >= modulus)
-                                result -= modulus;
-                }
+		// Reusing exponentLoopIndex to iterate again over the exponent range for the general-case accumulation.
+		exponentLoopIndex = 0UL;
+		// Reusing result after resetting it for the general modulus accumulation phase.
+		result = UInt128.One;
+		for (; exponentLoopIndex < exponent; exponentLoopIndex++)
+		{
+			result <<= 1;
+			if (result >= modulus)
+				result -= modulus;
+		}
 
-                return result;
-        }
+		return result;
+	}
 
 	/// <summary>
 	/// Computes 2^exponent mod modulus using a known cycle length.
 	/// </summary>
-        public static UInt128 PowModWithCycle(this ulong exponent, UInt128 modulus, ulong cycleLength)
-        {
-                UInt128 result = UInt128.One;
-                ulong exponentLoopIndex = 0UL;
-                ulong rotationCount = 0UL;
+	public static UInt128 PowModWithCycle(this ulong exponent, UInt128 modulus, ulong cycleLength)
+	{
+		UInt128 result = UInt128.One;
+		ulong exponentLoopIndex = 0UL;
 
-                // Return 1 because 2^0 = 1
-                if (exponent == 0UL)
-                        return result;
+		// Return 1 because 2^0 = 1
+		if (exponent == 0UL)
+			return result;
 
-                // Any number mod 1 is 0
-                if (modulus == UInt128.One)
-                        return UInt128.Zero;
+		// Any number mod 1 is 0
+		if (modulus == UInt128.One)
+			return UInt128.Zero;
 
-                // For small exponents, do classic method
-                if (exponent < 64 || modulus < 4)
-                {
-                        for (; exponentLoopIndex < exponent; exponentLoopIndex++)
-                        {
-                                result <<= 1;
-                                if (result >= modulus)
-                                        result -= modulus;
-                        }
+		// For small exponents, do classic method
+		if (exponent < 64 || modulus < 4)
+		{
+			for (; exponentLoopIndex < exponent; exponentLoopIndex++)
+			{
+				result <<= 1;
+				if (result >= modulus)
+					result -= modulus;
+			}
 
-                        return result;
-                }
+			return result;
+		}
 
-                // Special case: if modulus is a power of two, use bitmasking for efficiency and correctness
-                if ((modulus & (modulus - 1)) == 0)
-                {
-                        result = UInt128.One << (int)(exponent & 127);
-                        return result & (modulus - 1);
-                }
+		// Special case: if modulus is a power of two, use bitmasking for efficiency and correctness
+		if ((modulus & (modulus - 1)) == 0)
+		{
+			result = UInt128.One << (int)(exponent & 127);
+			return result & (modulus - 1);
+		}
 
-                // Reusing exponentLoopIndex to iterate over the rotation count for the cycle-aware path.
-                exponentLoopIndex = 0UL;
-                // Reusing result after resetting it for the rotation-accumulation pass.
-                result = UInt128.One;
-                rotationCount = exponent % cycleLength;
-                for (; exponentLoopIndex < rotationCount; exponentLoopIndex++)
-                {
-                        result <<= 1;
-                        if (result >= modulus)
-                                result -= modulus;
-                }
+		// Reusing exponentLoopIndex to iterate over the rotation count for the cycle-aware path.
+		exponentLoopIndex = 0UL;
+		// Reusing result after resetting it for the rotation-accumulation pass.
+		result = UInt128.One;
+		ulong rotationCount = exponent % cycleLength;
+		for (; exponentLoopIndex < rotationCount; exponentLoopIndex++)
+		{
+			result <<= 1;
+			if (result >= modulus)
+				result -= modulus;
+		}
 
-                return result;
-        }
+		return result;
+	}
 
 	/// <summary>
 	/// Computes 2^exponent mod modulus using a known cycle length.
 	/// </summary>
-        public static UInt128 PowModWithCycle(this ulong exponent, UInt128 modulus, UInt128 cycleLength)
-        {
-                UInt128 result = UInt128.One;
-                ulong exponentLoopIndex = 0UL;
-                UInt128 rotationIndex = UInt128.Zero;
-                UInt128 rotationCount = UInt128.Zero;
+	public static UInt128 PowModWithCycle(this ulong exponent, UInt128 modulus, UInt128 cycleLength)
+	{
+		UInt128 result = UInt128.One;
+		ulong exponentLoopIndex = 0UL;
 
-                // Return 1 because 2^0 = 1
-                if (exponent == UInt128.Zero)
-                        return result;
+		// Return 1 because 2^0 = 1
+		if (exponent == UInt128.Zero)
+			return result;
 
-                // Any number mod 1 is 0
-                if (modulus == UInt128.One)
-                        return UInt128.Zero;
+		// Any number mod 1 is 0
+		if (modulus == UInt128.One)
+			return UInt128.Zero;
 
-                // For small exponents, do classic method
-                if (exponent < UInt128Numbers.SixtyFour || modulus < UInt128Numbers.Four)
-                {
-                        for (; exponentLoopIndex < exponent; exponentLoopIndex++)
-                        {
-                                result <<= 1;
-                                if (result >= modulus)
-                                        result -= modulus;
-                        }
+		// For small exponents, do classic method
+		if (exponent < UInt128Numbers.SixtyFour || modulus < UInt128Numbers.Four)
+		{
+			for (; exponentLoopIndex < exponent; exponentLoopIndex++)
+			{
+				result <<= 1;
+				if (result >= modulus)
+					result -= modulus;
+			}
 
-                        return result;
-                }
+			return result;
+		}
 
-                // Special case: if modulus is a power of two, use bitmasking for efficiency and correctness
-                if ((modulus & (modulus - UInt128.One)) == UInt128.Zero)
-                {
-                        result = UInt128.One << (int)(exponent & UInt128Numbers.OneHundredTwentySeven);
-                        return result & (modulus - 1);
-                }
+		// Special case: if modulus is a power of two, use bitmasking for efficiency and correctness
+		if ((modulus & (modulus - UInt128.One)) == UInt128.Zero)
+		{
+			result = UInt128.One << (int)(exponent & UInt128Numbers.OneHundredTwentySeven);
+			return result & (modulus - 1);
+		}
 
-                // Reusing result after resetting it for the rotation-driven accumulation phase.
-                result = UInt128.One;
-                rotationCount = exponent % cycleLength;
-                rotationIndex = UInt128.Zero;
-                while (rotationIndex < rotationCount)
-                {
-                        result <<= 1;
-                        if (result >= modulus)
-                                result -= modulus;
+		// Reusing result after resetting it for the rotation-driven accumulation phase.
+		result = UInt128.One;
+		UInt128 rotationCount = exponent % cycleLength;
+		UInt128 rotationIndex = UInt128.Zero;
+		while (rotationIndex < rotationCount)
+		{
+			result <<= 1;
+			if (result >= modulus)
+				result -= modulus;
 
-                        rotationIndex += UInt128.One;
-                }
+			rotationIndex += UInt128.One;
+		}
 
-                return result;
-        }
+		return result;
+	}
 
 	/// <summary>
 	/// Computes 2^exponent mod modulus using a known cycle length.
 	/// </summary>
-        public static UInt128 PowModWithCycle(this UInt128 exponent, UInt128 modulus, UInt128 cycleLength)
-        {
-                UInt128 result = UInt128.One;
-                ulong exponentLoopIndex = 0UL;
-                UInt128 rotationIndex = UInt128.Zero;
-                UInt128 rotationCount = UInt128.Zero;
+	public static UInt128 PowModWithCycle(this UInt128 exponent, UInt128 modulus, UInt128 cycleLength)
+	{
+		UInt128 one = UInt128.One,
+				result = one,
+				zero = UInt128.Zero;
+		ulong exponentLoopIndex = 0UL;
 
-                // Return 1 because 2^0 = 1
-                if (exponent == UInt128.Zero)
-                        return result;
+		// Return 1 because 2^0 = 1
+		if (exponent == zero)
+			return result;
 
-                // Any number mod 1 is 0
-                if (modulus == UInt128.One)
-                        return UInt128.Zero;
+		// Any number mod 1 is 0
+		if (modulus == one)
+			return zero;
 
-                // For small exponents, do classic method
-                if (exponent < UInt128Numbers.SixtyFour || modulus < UInt128Numbers.Four)
-                {
-                        for (; exponentLoopIndex < exponent; exponentLoopIndex++)
-                        {
-                                result <<= 1;
-                                if (result >= modulus)
-                                        result -= modulus;
-                        }
+		// For small exponents, do classic method
+		if (exponent < UInt128Numbers.SixtyFour || modulus < UInt128Numbers.Four)
+		{
+			for (; exponentLoopIndex < exponent; exponentLoopIndex++)
+			{
+				result <<= 1;
+				if (result >= modulus)
+					result -= modulus;
+			}
 
-                        return result;
-                }
+			return result;
+		}
 
-                // Special case: if modulus is a power of two, use bitmasking for efficiency and correctness
-                if ((modulus & (modulus - UInt128.One)) == UInt128.Zero)
-                {
-                        result = UInt128.One << (int)(exponent & UInt128Numbers.OneHundredTwentySeven);
-                        return result & (modulus - 1);
-                }
+		// Special case: if modulus is a power of two, use bitmasking for efficiency and correctness
+		if ((modulus & (modulus - one)) == zero)
+		{
+			result = one << (int)(exponent & UInt128Numbers.OneHundredTwentySeven);
+			return result & (modulus - 1);
+		}
 
-                // Reusing result after resetting it for the rotation-driven accumulation phase.
-                result = UInt128.One;
-                rotationCount = exponent % cycleLength;
-                rotationIndex = UInt128.Zero;
-                while (rotationIndex < rotationCount)
-                {
-                        result <<= 1;
-                        if (result >= modulus)
-                                result -= modulus;
+		// Reusing result after resetting it for the rotation-driven accumulation phase.
+		result = one;
+		UInt128 rotationCount = exponent % cycleLength;
+		
+		// We're reusing "zero" as rotation index for just a little better performance
+		while (zero < rotationCount)
+		{
+			result <<= 1;
+			if (result >= modulus)
+				result -= modulus;
 
-                        rotationIndex += UInt128.One;
-                }
+			zero += one;
+		}
 
-                return result;
-        }
+		return result;
+	}
 
 	/// <summary>
 	/// Computes 2^exponent mod modulus using iterative CRT composition from mod 10 up to modulus.
 	/// Only for modulus >= 10 and reasonable size.
 	/// </summary>
-        public static UInt128 PowModCrt(this ulong exponent, UInt128 modulus, MersenneDivisorCycles cycles)
-        {
-                if (modulus < 10)
-                        return PowMod(exponent, modulus); // fallback to classic
+	public static UInt128 PowModCrt(this ulong exponent, UInt128 modulus, MersenneDivisorCycles cycles)
+	{
+		if (modulus < 10)
+			return PowMod(exponent, modulus); // fallback to classic
 
-                // Use cycle length 4 for mod 10
-                UInt128 result = PowModWithCycle(exponent, 10, 4);
-                UInt128 currentModulus = 10;
-                UInt128 modulusCandidate = 11;
-                UInt128 cycle = UInt128.Zero;
-                UInt128 remainderForCandidate = UInt128.Zero;
+		// Use cycle length 4 for mod 10
+		UInt128 currentModulus = 10,
+				cycle,
+				modulusCandidate = 11,
+				remainderForCandidate,
+				result = PowModWithCycle(exponent, 10, 4),
+				zero = UInt128.Zero;
 
-                for (; modulusCandidate <= modulus; modulusCandidate++)
-                {
-                        cycle = MersenneDivisorCycles.GetCycle(modulusCandidate);
-                        remainderForCandidate = cycle > UInt128.Zero
-                                ? PowModWithCycle(exponent, modulusCandidate, cycle)
-                                : PowMod(exponent, modulusCandidate);
+		for (; modulusCandidate <= modulus; modulusCandidate++)
+		{
+			cycle = MersenneDivisorCycles.GetCycle(modulusCandidate);
+			remainderForCandidate = cycle > zero
+					? PowModWithCycle(exponent, modulusCandidate, cycle)
+					: PowMod(exponent, modulusCandidate);
 
-                        // Solve x ≡ result mod currentModulus
-                        //      x ≡ remM   mod m
-                        // Find x mod (currentModulus * m)
-                        // Since currentModulus and m are coprime, use CRT:
-                        // x = result + currentModulus * t, where t ≡ (remM - result) * inv(currentModulus, m) mod m
+			// Solve x ≡ result mod currentModulus
+			//      x ≡ remM   mod m
+			// Find x mod (currentModulus * m)
+			// Since currentModulus and m are coprime, use CRT:
+			// x = result + currentModulus * t, where t ≡ (remM - result) * inv(currentModulus, m) mod m
 
-                        result += currentModulus * ((remainderForCandidate + modulusCandidate - (result % modulusCandidate)) * ModInverse(currentModulus, modulusCandidate) % modulusCandidate);
-                        currentModulus *= modulusCandidate;
+			result += currentModulus * ((remainderForCandidate + modulusCandidate - (result % modulusCandidate)) * ModInverse(currentModulus, modulusCandidate) % modulusCandidate);
+			currentModulus *= modulusCandidate;
 
-                        if (currentModulus >= modulus)
-                                break;
-                }
+			if (currentModulus >= modulus)
+				break;
+		}
 
-                return result % modulus;
-        }
+		return result % modulus;
+	}
 
-        // Helper: modular inverse (extended Euclidean algorithm)
-        private static UInt128 ModInverse(UInt128 a, UInt128 m)
-        {
-                UInt128 m0 = m, temp;
-                UInt128 x0 = 0, x1 = 1;
-                UInt128 originalA = UInt128.Zero;
-                UInt128 originalM = UInt128.Zero;
-                if (m == 1)
-                {
-                        return 0;
-                }
+	// Helper: modular inverse (extended Euclidean algorithm)
+	private static UInt128 ModInverse(UInt128 a, UInt128 m)
+	{
+		UInt128 m0 = m,
+				originalA,
+				originalM,
+				temp,
+				x0 = 0,
+				x1 = 1;
 
-                while (a > 1)
-                {
-                        originalA = a;
-                        originalM = m;
-                        m = originalA % originalM;
-                        a = originalM;
-                        temp = x0;
-                        x0 = x1 - (originalA / originalM) * x0;
-                        x1 = temp;
-                }
+		if (m == 1)
+		{
+			return 0;
+		}
 
-                if (x1 < 0)
-                {
-                        x1 += m0;
-                }
+		while (a > 1)
+		{
+			originalA = a;
+			originalM = m;
+			m = originalA % originalM;
+			a = originalM;
+			temp = x0;
+			x0 = x1 - (originalA / originalM) * x0;
+			x1 = temp;
+		}
 
-                return x1;
-        }
+		if (x1 < 0)
+		{
+			x1 += m0;
+		}
+
+		return x1;
+	}
 
 	[MethodImpl(MethodImplOptions.AggressiveInlining)]
 	public static bool SharesFactorWithExponentMinusOne(this ulong exponent)
 	{
-		ulong value = exponent - 1UL;
+		ulong prime, value = exponent - 1UL;
 		value >>= BitOperations.TrailingZeroCount(value);
 		uint[] smallPrimes = PrimesGenerator.SmallPrimes;
 		ulong[] smallPrimesPow2 = PrimesGenerator.SmallPrimesPow2;
 		int i = 1, smallPrimesLength = smallPrimes.Length;
-		ulong prime;
 
 		for (; i < smallPrimesLength && smallPrimesPow2[i] <= value; i++)
 		{