866 lines
28 KiB
C#
866 lines
28 KiB
C#
using System;
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using Open.Numeric.Primes;
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using System.Collections.Generic;
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using System.Numerics;
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using System.Runtime.CompilerServices;
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using System.Threading;
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using ILGPU;
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using ILGPU.Algorithms;
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using ILGPU.Runtime;
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using PerfectNumbers.Core.Gpu;
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namespace PerfectNumbers.Core;
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public sealed class HeuristicCombinedPrimeTester
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{
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static HeuristicCombinedPrimeTester()
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{
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HeuristicPrimeSieves.EnsureInitialized();
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CombinedDivisorsEnding1TwoAOneB = BuildCombinedDivisors(1, CombinedDivisorPattern.TwoAOneB);
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CombinedDivisorsEnding3TwoAOneB = BuildCombinedDivisors(3, CombinedDivisorPattern.TwoAOneB);
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CombinedDivisorsEnding7TwoAOneB = BuildCombinedDivisors(7, CombinedDivisorPattern.TwoAOneB);
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CombinedDivisorsEnding9TwoAOneB = BuildCombinedDivisors(9, CombinedDivisorPattern.TwoAOneB);
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CombinedDivisorsEnding1OneAOneB = BuildCombinedDivisors(1, CombinedDivisorPattern.OneAOneB);
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CombinedDivisorsEnding3OneAOneB = BuildCombinedDivisors(3, CombinedDivisorPattern.OneAOneB);
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CombinedDivisorsEnding7OneAOneB = BuildCombinedDivisors(7, CombinedDivisorPattern.OneAOneB);
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CombinedDivisorsEnding9OneAOneB = BuildCombinedDivisors(9, CombinedDivisorPattern.OneAOneB);
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CombinedDivisorsEnding1ThreeAOneB = BuildCombinedDivisors(1, CombinedDivisorPattern.ThreeAOneB);
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CombinedDivisorsEnding3ThreeAOneB = BuildCombinedDivisors(3, CombinedDivisorPattern.ThreeAOneB);
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CombinedDivisorsEnding7ThreeAOneB = BuildCombinedDivisors(7, CombinedDivisorPattern.ThreeAOneB);
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CombinedDivisorsEnding9ThreeAOneB = BuildCombinedDivisors(9, CombinedDivisorPattern.ThreeAOneB);
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CombinedDivisorsEnding1ThreeATwoB = BuildCombinedDivisors(1, CombinedDivisorPattern.ThreeATwoB);
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CombinedDivisorsEnding3ThreeATwoB = BuildCombinedDivisors(3, CombinedDivisorPattern.ThreeATwoB);
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CombinedDivisorsEnding7ThreeATwoB = BuildCombinedDivisors(7, CombinedDivisorPattern.ThreeATwoB);
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CombinedDivisorsEnding9ThreeATwoB = BuildCombinedDivisors(9, CombinedDivisorPattern.ThreeATwoB);
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}
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private const ulong Wheel210 = 210UL;
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private static readonly bool UseHeuristicGroupBTrialDivision = false; // Temporary fallback gate for Group B.
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private static readonly uint[] CombinedDivisorsEnding1TwoAOneB;
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private static readonly uint[] CombinedDivisorsEnding3TwoAOneB;
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private static readonly uint[] CombinedDivisorsEnding7TwoAOneB;
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private static readonly uint[] CombinedDivisorsEnding9TwoAOneB;
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private static readonly uint[] CombinedDivisorsEnding1OneAOneB;
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private static readonly uint[] CombinedDivisorsEnding3OneAOneB;
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private static readonly uint[] CombinedDivisorsEnding7OneAOneB;
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private static readonly uint[] CombinedDivisorsEnding9OneAOneB;
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private static readonly uint[] CombinedDivisorsEnding1ThreeAOneB;
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private static readonly uint[] CombinedDivisorsEnding3ThreeAOneB;
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private static readonly uint[] CombinedDivisorsEnding7ThreeAOneB;
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private static readonly uint[] CombinedDivisorsEnding9ThreeAOneB;
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private static readonly uint[] CombinedDivisorsEnding1ThreeATwoB;
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private static readonly uint[] CombinedDivisorsEnding3ThreeATwoB;
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private static readonly uint[] CombinedDivisorsEnding7ThreeATwoB;
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private static readonly uint[] CombinedDivisorsEnding9ThreeATwoB;
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private static readonly ulong[] HeuristicSmallCycleSnapshot = MersenneDivisorCycles.Shared.ExportSmallCyclesSnapshot();
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internal enum CombinedDivisorPattern : byte
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{
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TwoAOneB = 0,
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OneAOneB = 1,
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ThreeAOneB = 2,
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ThreeATwoB = 3,
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}
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internal enum HeuristicDivisorGroup : byte
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{
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None = 0,
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GroupAConstant = 1,
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GroupAWheel = 2,
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GroupB = 3,
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}
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internal readonly struct HeuristicDivisorCandidate(ulong value, HeuristicDivisorGroup group, byte ending, byte priorityIndex, ushort wheelResidue)
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{
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public readonly ulong Value = value;
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public readonly HeuristicDivisorGroup Group = group;
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public readonly byte Ending = ending;
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public readonly byte PriorityIndex = priorityIndex;
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public readonly ushort WheelResidue = wheelResidue;
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}
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internal readonly struct HeuristicDivisorPreparation(
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in HeuristicDivisorCandidate candidate,
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in MontgomeryDivisorData divisorData,
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ulong cycleLengthHint,
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bool hasCycleLengthHint)
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{
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public readonly HeuristicDivisorCandidate Candidate = candidate;
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public readonly MontgomeryDivisorData DivisorData = divisorData;
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public readonly ulong CycleLengthHint = cycleLengthHint;
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public readonly bool HasCycleLengthHint = hasCycleLengthHint;
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public readonly bool RequiresCycleComputation = !hasCycleLengthHint;
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}
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public static int HeuristicGpuDivisorBatchSize { get; set; } = 4_096;
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public static int HeuristicDivisorInterleaveBatchSize { get; set; } = 64;
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[ThreadStatic]
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private static HeuristicCombinedPrimeTester? _tester;
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public static HeuristicCombinedPrimeTester Exclusive => _tester ??= new();
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public bool IsPrimeCpu(ulong n, CancellationToken ct)
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{
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ct.ThrowIfCancellationRequested();
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byte nMod10 = (byte)n.Mod10();
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ulong sqrtLimit = ComputeHeuristicSqrt(n);
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if (sqrtLimit < 3UL)
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{
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return EvaluateWithOpenNumericFallback(n);
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}
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bool includeGroupB = UseHeuristicGroupBTrialDivision;
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return HeuristicTrialDivisionCpu(n, sqrtLimit, nMod10, includeGroupB);
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}
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public bool IsPrimeCpu(ulong n)
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{
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return IsPrimeCpu(n, CancellationToken.None);
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}
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public bool IsPrimeGpu(ulong n)
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{
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byte nMod10 = (byte)n.Mod10();
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ulong sqrtLimit = ComputeHeuristicSqrt(n);
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return IsPrimeGpu(n, sqrtLimit, nMod10);
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}
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public bool IsPrimeGpu(ulong n, ulong sqrtLimit, byte nMod10)
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{
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return HeuristicIsPrimeGpuCore(n, sqrtLimit, nMod10);
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}
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private bool HeuristicIsPrimeGpuCore(ulong n, ulong sqrtLimit, byte nMod10)
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{
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// TODO: Is this condition ever met on the execution path in EvenPerfectBitScanner?
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if (sqrtLimit < 3UL)
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{
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return EvaluateWithOpenNumericFallback(n);
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}
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if (!UseHeuristicGroupBTrialDivision)
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{
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return HeuristicTrialDivisionCpu(n, sqrtLimit, nMod10, includeGroupB: false);
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}
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bool compositeDetected = HeuristicTrialDivisionGpuDetectsDivisor(n, sqrtLimit, nMod10);
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return !compositeDetected;
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}
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private static bool HeuristicTrialDivisionCpu(ulong n, ulong sqrtLimit, byte nMod10, bool includeGroupB)
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{
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ReadOnlySpan<uint> combinedDivisors = GetCombinedDivisors(nMod10);
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if (combinedDivisors.IsEmpty)
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{
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return EvaluateWithOpenNumericFallback(n);
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}
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int targetGroupACount = CountGroupAEntriesUpTo(sqrtLimit);
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int targetGroupBCount = includeGroupB ? CountGroupBEntriesUpTo(sqrtLimit, nMod10) : 0;
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if (targetGroupACount == 0 && (!includeGroupB || targetGroupBCount == 0))
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{
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return EvaluateWithOpenNumericFallback(n);
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}
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int processedA = 0;
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int processedB = 0;
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for (int i = 0; i < combinedDivisors.Length; i++)
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{
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uint entry = combinedDivisors[i];
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HeuristicDivisorGroup group = ResolveGroup(entry);
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if (group == HeuristicDivisorGroup.GroupB)
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{
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if (!includeGroupB)
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{
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continue;
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}
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if (processedB >= targetGroupBCount)
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{
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if (processedA >= targetGroupACount)
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{
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break;
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}
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continue;
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}
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processedB++;
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}
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else
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{
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if (processedA >= targetGroupACount)
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{
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if (!includeGroupB || processedB >= targetGroupBCount)
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{
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break;
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}
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continue;
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}
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processedA++;
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}
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ulong divisor = entry;
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if (divisor > sqrtLimit)
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{
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continue;
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}
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if (n % divisor == 0UL)
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{
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return false;
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}
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if (processedA >= targetGroupACount && (!includeGroupB || processedB >= targetGroupBCount))
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{
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break;
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}
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}
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return EvaluateWithOpenNumericFallback(n);
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}
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private bool HeuristicTrialDivisionGpuDetectsDivisor(ulong n, ulong sqrtLimit, byte nMod10)
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{
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int batchCapacity = Math.Max(1, HeuristicGpuDivisorBatchSize);
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var divisorPool = ThreadStaticPools.UlongPool;
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var hitPool = ThreadStaticPools.BytePool;
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ulong[] divisorArray = divisorPool.Rent(batchCapacity);
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byte[] hitFlags = hitPool.Rent(batchCapacity);
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var limiter = GpuPrimeWorkLimiter.Acquire();
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var gpu = PrimeTester.PrimeTesterGpuContextPool.Rent();
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var accelerator = gpu.Accelerator;
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var state = PrimeTester.GpuKernelState.GetOrCreate(accelerator);
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var scratch = state.RentScratch(batchCapacity, accelerator);
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bool compositeDetected = false;
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int count = 0;
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lock (gpu.ExecutionLock)
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{
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var input = scratch.Input;
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var output = scratch.Output;
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bool ProcessBatch(int length)
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{
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if (length <= 0)
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{
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return false;
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}
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input.View.CopyFromCPU(ref divisorArray[0], length);
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state.HeuristicTrialDivisionKernel(length, input.View, n, output.View);
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accelerator.Synchronize();
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output.View.CopyToCPU(ref hitFlags[0], length);
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for (int i = 0; i < length; i++)
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{
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if (hitFlags[i] == 0)
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{
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continue;
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}
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ulong divisor = divisorArray[i];
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if (divisor > 1UL && n % divisor == 0UL)
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{
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return true;
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}
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}
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return false;
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}
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ReadOnlySpan<uint> combinedDivisors = GetCombinedDivisors(nMod10);
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if (combinedDivisors.IsEmpty)
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{
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compositeDetected = !EvaluateWithOpenNumericFallback(n);
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goto Cleanup;
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}
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int targetGroupACount = CountGroupAEntriesUpTo(sqrtLimit);
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int targetGroupBCount = CountGroupBEntriesUpTo(sqrtLimit, nMod10);
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bool includeGroupB = targetGroupBCount > 0;
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if (targetGroupACount == 0 && !includeGroupB)
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{
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compositeDetected = !EvaluateWithOpenNumericFallback(n);
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goto Cleanup;
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}
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int processedA = 0;
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int processedB = 0;
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for (int i = 0; i < combinedDivisors.Length; i++)
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{
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uint entry = combinedDivisors[i];
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HeuristicDivisorGroup group = ResolveGroup(entry);
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if (group == HeuristicDivisorGroup.GroupB)
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{
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if (!includeGroupB)
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{
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continue;
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}
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if (processedB >= targetGroupBCount)
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{
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if (processedA >= targetGroupACount)
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{
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break;
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}
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continue;
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}
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processedB++;
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}
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else
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{
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if (processedA >= targetGroupACount)
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{
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if (!includeGroupB || processedB >= targetGroupBCount)
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{
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break;
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}
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continue;
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}
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processedA++;
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}
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ulong divisor = entry;
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if (divisor > sqrtLimit)
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{
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continue;
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}
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divisorArray[count] = divisor;
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count++;
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if (count == batchCapacity)
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{
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if (ProcessBatch(count))
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{
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compositeDetected = true;
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goto Cleanup;
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}
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count = 0;
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}
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if (processedA >= targetGroupACount && (!includeGroupB || processedB >= targetGroupBCount))
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{
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break;
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}
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}
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if (!compositeDetected && count > 0)
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{
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if (ProcessBatch(count))
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{
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compositeDetected = true;
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goto Cleanup;
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}
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count = 0;
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}
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}
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Cleanup:
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state.ReturnScratch(scratch);
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divisorPool.Return(divisorArray);
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hitPool.Return(hitFlags);
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gpu.Dispose();
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limiter.Dispose();
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return compositeDetected;
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}
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private static bool EvaluateWithOpenNumericFallback(ulong n)
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{
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return Prime.Numbers.IsPrime(n);
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}
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internal static ulong ComputeHeuristicSqrt(ulong n)
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{
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ulong sqrt = (ulong)Math.Sqrt(n);
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UInt128 square = (UInt128)sqrt * sqrt;
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while (square > n)
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{
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sqrt--;
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square = (UInt128)sqrt * sqrt;
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}
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ulong next = sqrt + 1UL;
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UInt128 nextSquare = (UInt128)next * next;
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while (nextSquare <= n)
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{
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sqrt = next;
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next++;
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nextSquare = (UInt128)next * next;
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}
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return sqrt;
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}
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private static ReadOnlySpan<uint> GetCombinedDivisors(byte nMod10)
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{
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return GetCombinedDivisors(nMod10, CombinedDivisorPattern.OneAOneB);
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}
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internal static ReadOnlySpan<uint> GetCombinedDivisors(byte nMod10, CombinedDivisorPattern pattern)
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{
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return pattern switch
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{
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CombinedDivisorPattern.TwoAOneB => nMod10 switch
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{
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1 => CombinedDivisorsEnding1TwoAOneB,
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3 => CombinedDivisorsEnding3TwoAOneB,
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7 => CombinedDivisorsEnding7TwoAOneB,
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9 => CombinedDivisorsEnding9TwoAOneB,
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_ => ReadOnlySpan<uint>.Empty,
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},
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CombinedDivisorPattern.OneAOneB => nMod10 switch
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{
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1 => CombinedDivisorsEnding1OneAOneB,
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3 => CombinedDivisorsEnding3OneAOneB,
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7 => CombinedDivisorsEnding7OneAOneB,
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9 => CombinedDivisorsEnding9OneAOneB,
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_ => ReadOnlySpan<uint>.Empty,
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},
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CombinedDivisorPattern.ThreeAOneB => nMod10 switch
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{
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1 => CombinedDivisorsEnding1ThreeAOneB,
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3 => CombinedDivisorsEnding3ThreeAOneB,
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7 => CombinedDivisorsEnding7ThreeAOneB,
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9 => CombinedDivisorsEnding9ThreeAOneB,
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_ => ReadOnlySpan<uint>.Empty,
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},
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CombinedDivisorPattern.ThreeATwoB => nMod10 switch
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{
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1 => CombinedDivisorsEnding1ThreeATwoB,
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3 => CombinedDivisorsEnding3ThreeATwoB,
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7 => CombinedDivisorsEnding7ThreeATwoB,
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9 => CombinedDivisorsEnding9ThreeATwoB,
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_ => ReadOnlySpan<uint>.Empty,
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},
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_ => ReadOnlySpan<uint>.Empty,
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};
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}
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private static uint[] BuildCombinedDivisors(byte nMod10, CombinedDivisorPattern pattern)
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{
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ReadOnlySpan<int> groupA = HeuristicPrimeSieves.GroupADivisors;
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ReadOnlySpan<uint> groupB = GetGroupBDivisors(nMod10);
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var combined = new List<uint>(groupA.Length + groupB.Length);
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int groupAIndex = 0;
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while (groupAIndex < groupA.Length && groupA[groupAIndex] <= 19)
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{
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combined.Add((uint)groupA[groupAIndex]);
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groupAIndex++;
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}
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int groupBIndex = GetGroupBStartIndex(groupB);
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int groupAInterleaveCount;
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int groupBInterleaveCount;
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switch (pattern)
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{
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case CombinedDivisorPattern.OneAOneB:
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groupAInterleaveCount = 1;
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groupBInterleaveCount = 1;
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break;
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case CombinedDivisorPattern.TwoAOneB:
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groupAInterleaveCount = 2;
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groupBInterleaveCount = 1;
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break;
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case CombinedDivisorPattern.ThreeAOneB:
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groupAInterleaveCount = 3;
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groupBInterleaveCount = 1;
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break;
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case CombinedDivisorPattern.ThreeATwoB:
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groupAInterleaveCount = 3;
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groupBInterleaveCount = 2;
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break;
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default:
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groupAInterleaveCount = 2;
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groupBInterleaveCount = 1;
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break;
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}
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while (groupAIndex < groupA.Length || groupBIndex < groupB.Length)
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{
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int addedA = 0;
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while (addedA < groupAInterleaveCount && groupAIndex < groupA.Length)
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{
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combined.Add((uint)groupA[groupAIndex]);
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groupAIndex++;
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addedA++;
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}
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int addedB = 0;
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while (addedB < groupBInterleaveCount && groupBIndex < groupB.Length)
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{
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combined.Add(groupB[groupBIndex]);
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groupBIndex++;
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addedB++;
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}
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}
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return combined.ToArray();
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}
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private static int CountGroupAEntriesUpTo(ulong sqrtLimit)
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{
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ReadOnlySpan<int> groupA = HeuristicPrimeSieves.GroupADivisors;
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int count = 0;
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while (count < groupA.Length && (ulong)groupA[count] <= sqrtLimit)
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{
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count++;
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}
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return count;
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}
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private static int CountGroupBEntriesUpTo(ulong sqrtLimit, byte nMod10)
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|
{
|
|
ReadOnlySpan<uint> divisors = GetGroupBDivisors(nMod10);
|
|
if (divisors.IsEmpty)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
int index = GetGroupBStartIndex(divisors);
|
|
int count = 0;
|
|
|
|
for (int i = index; i < divisors.Length; i++)
|
|
{
|
|
if ((ulong)divisors[i] > sqrtLimit)
|
|
{
|
|
break;
|
|
}
|
|
|
|
count++;
|
|
}
|
|
|
|
return count;
|
|
}
|
|
|
|
private static int GetGroupBStartIndex(ReadOnlySpan<uint> divisors)
|
|
{
|
|
int index = 0;
|
|
while (index < divisors.Length && IsGroupAPrefixValue(divisors[index]))
|
|
{
|
|
index++;
|
|
}
|
|
|
|
return index;
|
|
}
|
|
|
|
private static bool IsGroupAPrefixValue(uint value) => value is 3U or 7U or 11U or 13U;
|
|
|
|
private static HeuristicDivisorGroup ResolveGroup(uint value) => value switch
|
|
{
|
|
3U or 7U or 11U or 13U => HeuristicDivisorGroup.GroupAConstant,
|
|
_ when value % 10U == 3U => HeuristicDivisorGroup.GroupAWheel,
|
|
_ => HeuristicDivisorGroup.GroupB,
|
|
};
|
|
|
|
private static ReadOnlySpan<uint> GetGroupBDivisors(byte ending) => ending switch
|
|
{
|
|
1 => DivisorGenerator.SmallPrimesLastOneWithoutLastThree,
|
|
3 => ReadOnlySpan<uint>.Empty,
|
|
7 => DivisorGenerator.SmallPrimesLastSevenWithoutLastThree,
|
|
9 => DivisorGenerator.SmallPrimesLastNineWithoutLastThree,
|
|
_ => ReadOnlySpan<uint>.Empty,
|
|
};
|
|
|
|
[MethodImpl(MethodImplOptions.AggressiveInlining)]
|
|
internal static HeuristicDivisorEnumerator CreateHeuristicDivisorEnumerator(ulong sqrtLimit, byte nMod10, Span<HeuristicGroupBSequenceState> groupBBuffer)
|
|
{
|
|
return new HeuristicDivisorEnumerator(sqrtLimit, nMod10, groupBBuffer);
|
|
}
|
|
|
|
internal struct HeuristicGroupBSequenceState
|
|
{
|
|
}
|
|
|
|
[MethodImpl(MethodImplOptions.AggressiveInlining)]
|
|
internal static MersenneHeuristicDivisorEnumerator CreateMersenneDivisorEnumerator(ulong exponent, ulong maxDivisor)
|
|
{
|
|
return new MersenneHeuristicDivisorEnumerator(exponent, maxDivisor);
|
|
}
|
|
|
|
[MethodImpl(MethodImplOptions.AggressiveInlining)]
|
|
internal static HeuristicDivisorPreparation PrepareHeuristicDivisor(in HeuristicDivisorCandidate candidate)
|
|
{
|
|
ulong divisor = candidate.Value;
|
|
MontgomeryDivisorData divisorData = MontgomeryDivisorData.FromModulus(divisor);
|
|
bool hasCycleHint = TryGetCycleLengthHint(divisor, out ulong cycleLength);
|
|
return new HeuristicDivisorPreparation(candidate, divisorData, cycleLength, hasCycleHint);
|
|
}
|
|
|
|
[MethodImpl(MethodImplOptions.AggressiveInlining)]
|
|
internal static ulong ResolveHeuristicCycleLength(
|
|
ulong exponent,
|
|
in HeuristicDivisorPreparation preparation,
|
|
out bool cycleFromHint,
|
|
out bool cycleComputed,
|
|
out bool primeOrderFailed)
|
|
{
|
|
if (preparation.HasCycleLengthHint && preparation.CycleLengthHint != 0UL)
|
|
{
|
|
cycleFromHint = true;
|
|
cycleComputed = true;
|
|
primeOrderFailed = false;
|
|
return preparation.CycleLengthHint;
|
|
}
|
|
|
|
ulong divisor = preparation.Candidate.Value;
|
|
MontgomeryDivisorData divisorData = preparation.DivisorData;
|
|
|
|
bool trySuccess = MersenneDivisorCycles.TryCalculateCycleLengthForExponentCpu(
|
|
divisor,
|
|
exponent,
|
|
divisorData,
|
|
out ulong computedCycle,
|
|
out bool primeOrderFailedLocal);
|
|
|
|
if (trySuccess && computedCycle != 0UL)
|
|
{
|
|
cycleFromHint = false;
|
|
cycleComputed = true;
|
|
primeOrderFailed = primeOrderFailedLocal;
|
|
return computedCycle;
|
|
}
|
|
|
|
primeOrderFailed = primeOrderFailedLocal || !trySuccess || computedCycle == 0UL;
|
|
ulong resolvedCycle = MersenneDivisorCycles.CalculateCycleLength(divisor, divisorData, skipPrimeOrderHeuristic: primeOrderFailed);
|
|
cycleFromHint = false;
|
|
cycleComputed = resolvedCycle != 0UL;
|
|
return resolvedCycle;
|
|
}
|
|
|
|
[MethodImpl(MethodImplOptions.AggressiveInlining)]
|
|
internal static bool TryGetCycleLengthHint(ulong divisor, out ulong cycleLength)
|
|
{
|
|
ulong[] snapshot = HeuristicSmallCycleSnapshot;
|
|
if (divisor < (ulong)snapshot.Length)
|
|
{
|
|
cycleLength = snapshot[(int)divisor];
|
|
if (cycleLength != 0UL)
|
|
{
|
|
return true;
|
|
}
|
|
}
|
|
|
|
cycleLength = 0UL;
|
|
return false;
|
|
}
|
|
|
|
internal ref struct HeuristicDivisorEnumerator
|
|
{
|
|
private readonly ulong sqrtLimit;
|
|
private readonly ReadOnlySpan<uint> combinedDivisors;
|
|
private readonly bool includeGroupB;
|
|
private readonly int targetGroupACount;
|
|
private readonly int targetGroupBCount;
|
|
private int index;
|
|
private int processedA;
|
|
private int processedB;
|
|
|
|
public HeuristicDivisorEnumerator(ulong sqrtLimit, byte nMod10, Span<HeuristicGroupBSequenceState> groupBBuffer)
|
|
{
|
|
this.sqrtLimit = sqrtLimit;
|
|
_ = groupBBuffer;
|
|
combinedDivisors = GetCombinedDivisors(nMod10);
|
|
targetGroupACount = CountGroupAEntriesUpTo(sqrtLimit);
|
|
targetGroupBCount = CountGroupBEntriesUpTo(sqrtLimit, nMod10);
|
|
includeGroupB = targetGroupBCount > 0;
|
|
index = 0;
|
|
processedA = 0;
|
|
processedB = 0;
|
|
}
|
|
|
|
public bool TryGetNext(out HeuristicDivisorCandidate candidate)
|
|
{
|
|
while (index < combinedDivisors.Length)
|
|
{
|
|
uint entry = combinedDivisors[index++];
|
|
HeuristicDivisorGroup group = ResolveGroup(entry);
|
|
|
|
if (group == HeuristicDivisorGroup.GroupB)
|
|
{
|
|
if (!includeGroupB)
|
|
{
|
|
continue;
|
|
}
|
|
|
|
if (processedB >= targetGroupBCount)
|
|
{
|
|
if (processedA >= targetGroupACount)
|
|
{
|
|
break;
|
|
}
|
|
|
|
continue;
|
|
}
|
|
|
|
processedB++;
|
|
}
|
|
else
|
|
{
|
|
if (processedA >= targetGroupACount)
|
|
{
|
|
if (!includeGroupB || processedB >= targetGroupBCount)
|
|
{
|
|
break;
|
|
}
|
|
|
|
continue;
|
|
}
|
|
|
|
processedA++;
|
|
}
|
|
|
|
ulong value = entry;
|
|
if (value > sqrtLimit)
|
|
{
|
|
continue;
|
|
}
|
|
|
|
byte ending = (byte)(value % 10UL);
|
|
ushort residue = (ushort)(value % Wheel210);
|
|
candidate = new HeuristicDivisorCandidate(value, group, ending, 0, residue);
|
|
return true;
|
|
}
|
|
|
|
candidate = default;
|
|
return false;
|
|
}
|
|
}
|
|
|
|
internal ref struct MersenneHeuristicDivisorEnumerator
|
|
{
|
|
private readonly GpuUInt128 step;
|
|
private readonly GpuUInt128 limit;
|
|
private GpuUInt128 current;
|
|
private MersenneDivisorResidueStepper residueStepper;
|
|
private bool active;
|
|
private ulong processedCount;
|
|
private ulong lastDivisor;
|
|
|
|
public MersenneHeuristicDivisorEnumerator(ulong exponent, ulong maxDivisor)
|
|
{
|
|
var stepLocal = new GpuUInt128(exponent);
|
|
stepLocal.ShiftLeft(1);
|
|
step = stepLocal;
|
|
|
|
var limitLocal = new GpuUInt128(maxDivisor);
|
|
limit = limitLocal;
|
|
|
|
var firstDivisor = stepLocal;
|
|
firstDivisor.Add(1UL);
|
|
|
|
bool hasCandidates = !stepLocal.IsZero && firstDivisor.CompareTo(limitLocal) <= 0;
|
|
|
|
current = hasCandidates ? firstDivisor : GpuUInt128.Zero;
|
|
residueStepper = hasCandidates ? new MersenneDivisorResidueStepper(exponent, stepLocal, firstDivisor) : default;
|
|
active = hasCandidates;
|
|
processedCount = 0UL;
|
|
lastDivisor = 0UL;
|
|
}
|
|
|
|
public bool TryGetNext(out HeuristicDivisorCandidate candidate)
|
|
{
|
|
while (active)
|
|
{
|
|
ulong value = current.Low;
|
|
processedCount++;
|
|
lastDivisor = value;
|
|
|
|
bool admissible = residueStepper.IsAdmissible();
|
|
|
|
Advance();
|
|
|
|
if (admissible)
|
|
{
|
|
candidate = CreateCandidate(value);
|
|
return true;
|
|
}
|
|
}
|
|
|
|
candidate = default;
|
|
return false;
|
|
}
|
|
|
|
private void Advance()
|
|
{
|
|
GpuUInt128 next = current;
|
|
next.Add(step);
|
|
|
|
if (next.CompareTo(limit) > 0 || next.CompareTo(current) <= 0)
|
|
{
|
|
active = false;
|
|
return;
|
|
}
|
|
|
|
current = next;
|
|
residueStepper.Advance();
|
|
}
|
|
|
|
public ulong ProcessedCount => processedCount;
|
|
|
|
public ulong LastDivisor => lastDivisor;
|
|
|
|
public bool Exhausted => !active;
|
|
|
|
private static HeuristicDivisorCandidate CreateCandidate(ulong value)
|
|
{
|
|
byte ending = (byte)(value % 10UL);
|
|
HeuristicDivisorGroup group;
|
|
|
|
if (value == 3UL || value == 7UL || value == 11UL || value == 13UL)
|
|
{
|
|
group = HeuristicDivisorGroup.GroupAConstant;
|
|
}
|
|
else if (ending == 3)
|
|
{
|
|
group = HeuristicDivisorGroup.GroupAWheel;
|
|
}
|
|
else
|
|
{
|
|
group = HeuristicDivisorGroup.GroupB;
|
|
}
|
|
|
|
ushort residue = (ushort)(value % Wheel210);
|
|
return new HeuristicDivisorCandidate(value, group, ending, 0, residue);
|
|
}
|
|
}
|
|
}
|