No. of divisor cycle iterations made configurable

EvenPerfectBitScanner/Program.cs

@@ -31,7 +31,6 @@ internal static class Program
 	private static ulong _divisor;
 	private static MersenneNumberDivisorGpuTester? _divisorTester;
 	private static (ulong divisor, uint cycle)[]? _divisorCandidates;
-private const int ExtraDivisorCycleSearchLimit = 32;
 	private static ulong? _orderWarmupLimitOverride;
 	private static unsafe delegate*<ulong, ref ulong, ulong> _transformP;
 	private static long _state;
@@ -76,6 +75,7 @@ private static ulong? _orderWarmupLimitOverride;
 		string cyclesPath = DefaultCyclesPath;
 		int cyclesBatchSize = 512;
 		bool continueCyclesGeneration = false;
+		int divisorCyclesSearchLimit = PerfectNumberConstants.ExtraDivisorCycleSearchLimit;
 
 		// NTT backend selection (GPU): reference vs staged
 		for (int i = 0; i < args.Length; i++)
@@ -137,6 +137,11 @@ private static ulong? _orderWarmupLimitOverride;
 				int eq = arg.IndexOf('=');
 				divisor = ulong.Parse(arg.AsSpan(eq + 1));
 			}
+			else if (arg.StartsWith("--divisor-cycles-limit=", StringComparison.OrdinalIgnoreCase))
+			{
+				int eq = arg.IndexOf('=');
+				divisorCyclesSearchLimit = int.Parse(arg.AsSpan(eq + 1));
+			}
 			else if (arg.StartsWith("--residue-max-k=", StringComparison.OrdinalIgnoreCase))
 			{
 				int eq = arg.IndexOf('=');
@@ -714,6 +719,7 @@ private static ulong? _orderWarmupLimitOverride;
 		Console.WriteLine("  --divisor-cycles-device=cpu|gpu  device for cycles generation (default gpu)");
 		Console.WriteLine("  --divisor-cycles-batch-size=<value> batch size for cycles generation (default 512)");
 		Console.WriteLine("  --divisor-cycles-continue  continue divisor cycles generation");
+		Console.WriteLine("  --divisor-cycles-limit=<value> cycle search iterations when --mersenne=divisor");
 
 		Console.WriteLine("  --use-order            test primality via q order");
 		Console.WriteLine("  --workaround-mod       avoid '%' operator on the GPU");
@@ -948,7 +954,7 @@ private static ulong? _orderWarmupLimitOverride;
 		return IsEvenPerfectCandidate(p, out _, out _);
 	}
 
-	internal static bool IsEvenPerfectCandidate(ulong p, out bool searchedMersenne, out bool detailedCheck)
+	internal static bool IsEvenPerfectCandidate(ulong p, int divisorCyclesSearchLimit, out bool searchedMersenne, out bool detailedCheck)
 	{
 		searchedMersenne = false;
 		detailedCheck = false;
@@ -1043,7 +1049,7 @@ private static ulong? _orderWarmupLimitOverride;
 				}
 			}
 
-                        for (int k = 1; k <= ExtraDivisorCycleSearchLimit; k++)
+			for (int k = 1; k <= divisorCyclesSearchLimit; k++)
 			{
 				ulong kMul2 = 2UL * (ulong)k;
 				if (p > ulong.MaxValue / kMul2)

PerfectNumbers.Core/PerfectNumberConstants.cs

@@ -5,4 +5,6 @@ public static class PerfectNumberConstants
 	public const ulong BiggestKnownEvenPerfectP = 136279841UL;
 	public static readonly uint PrimesLimit = 1_000_000; //(ulong)Array.MaxLength;// 1_000_000;
 	public const int MaxQForDivisorCycles = 4_000_000;
+	public const int ExtraDivisorCycleSearchLimit = 64;
+
 }