Files
even-perfect-numbers-scanner/PerfectNumbers.Core/Cpu/MersenneNumberDivisorByDivisorCpuTester.cs
T

563 lines
22 KiB
C#

using System;
using System.Buffers;
using System.Collections.Concurrent;
using System.Runtime.CompilerServices;
using PerfectNumbers.Core;
using PerfectNumbers.Core.Gpu;
using MontgomeryDivisorData = PerfectNumbers.Core.Gpu.MersenneNumberDivisorByDivisorGpuTester.MontgomeryDivisorData;
namespace PerfectNumbers.Core.Cpu;
public sealed class MersenneNumberDivisorByDivisorCpuTester : IMersenneNumberDivisorByDivisorTester
{
private readonly object _sync = new();
private readonly ConcurrentBag<DivisorScanSession> _sessionPool = new();
private ulong _divisorLimit;
private ulong _lastStatusDivisor;
private bool _isConfigured;
private bool _useDivisorCycles;
private int _batchSize = 1_024;
public bool UseDivisorCycles
{
get => _useDivisorCycles;
set => _useDivisorCycles = value;
}
public int BatchSize
{
get => _batchSize;
set => _batchSize = Math.Max(1, value);
}
public void ConfigureFromMaxPrime(ulong maxPrime)
{
lock (_sync)
{
_divisorLimit = ComputeDivisorLimitFromMaxPrime(maxPrime);
_lastStatusDivisor = 0UL;
_isConfigured = true;
}
}
public ulong DivisorLimit
{
get
{
lock (_sync)
{
if (!_isConfigured)
{
throw new InvalidOperationException("ConfigureFromMaxPrime must be called before using the tester.");
}
return _divisorLimit;
}
}
}
public ulong GetAllowedMaxDivisor(ulong prime)
{
lock (_sync)
{
if (!_isConfigured)
{
throw new InvalidOperationException("ConfigureFromMaxPrime must be called before using the tester.");
}
return ComputeAllowedMaxDivisor(prime, _divisorLimit);
}
}
public bool IsPrime(ulong prime, out bool divisorsExhausted)
{
ulong allowedMax;
bool useCycles;
int batchCapacity;
lock (_sync)
{
if (!_isConfigured)
{
throw new InvalidOperationException("ConfigureFromMaxPrime must be called before using the tester.");
}
allowedMax = ComputeAllowedMaxDivisor(prime, _divisorLimit);
useCycles = _useDivisorCycles;
batchCapacity = _batchSize;
}
if (allowedMax < 3UL)
{
divisorsExhausted = true;
return true;
}
ulong[] divisors = ArrayPool<ulong>.Shared.Rent(batchCapacity);
byte[] hits = ArrayPool<byte>.Shared.Rent(batchCapacity);
MontgomeryDivisorData[] divisorData = ArrayPool<MontgomeryDivisorData>.Shared.Rent(batchCapacity);
ulong processedCount = 0UL;
ulong lastProcessed = 0UL;
bool composite = false;
bool processedAll = false;
try
{
composite = CheckDivisors(
prime,
allowedMax,
useCycles,
divisors,
hits,
divisorData,
out lastProcessed,
out processedAll,
out processedCount);
}
finally
{
ArrayPool<ulong>.Shared.Return(divisors, clearArray: false);
ArrayPool<byte>.Shared.Return(hits, clearArray: false);
ArrayPool<MontgomeryDivisorData>.Shared.Return(divisorData, clearArray: false);
}
if (processedCount > 0UL)
{
lock (_sync)
{
UpdateStatusUnsafe(lastProcessed, processedCount);
}
}
if (composite)
{
divisorsExhausted = true;
return false;
}
divisorsExhausted = processedAll || composite;
return true;
}
public IMersenneNumberDivisorByDivisorTester.IDivisorScanSession CreateDivisorSession()
{
lock (_sync)
{
if (!_isConfigured)
{
throw new InvalidOperationException("ConfigureFromMaxPrime must be called before using the tester.");
}
if (_sessionPool.TryTake(out DivisorScanSession? session))
{
session.Reset();
return session;
}
return new DivisorScanSession(this);
}
}
private void ReturnSession(DivisorScanSession session)
{
_sessionPool.Add(session);
}
private bool CheckDivisors(
ulong prime,
ulong allowedMax,
bool useCycles,
ulong[] divisors,
byte[] hits,
MontgomeryDivisorData[] divisorData,
out ulong lastProcessed,
out bool processedAll,
out ulong processedCount)
{
lastProcessed = 0UL;
processedCount = 0UL;
processedAll = false;
if (allowedMax < 3UL)
{
return false;
}
int batchCapacity = _batchSize;
ulong divisor = 3UL;
bool composite = false;
while (divisor <= allowedMax)
{
int batchSize = 0;
bool reachedEndInBatch = false;
while (batchSize < batchCapacity && divisor <= allowedMax)
{
ulong currentDivisor = divisor;
ulong nextDivisor = currentDivisor + 2UL;
divisors[batchSize++] = currentDivisor;
processedCount++;
lastProcessed = currentDivisor;
if (nextDivisor <= currentDivisor)
{
reachedEndInBatch = true;
break;
}
if (nextDivisor > allowedMax)
{
divisor = nextDivisor;
reachedEndInBatch = true;
break;
}
divisor = nextDivisor;
}
if (batchSize == 0)
{
if (reachedEndInBatch)
{
processedAll = true;
}
break;
}
Span<MontgomeryDivisorData> divisorDataSpan = divisorData.AsSpan(0, batchSize);
Span<ulong> divisorSpan = divisors.AsSpan(0, batchSize);
Span<byte> hitsSpan = hits.AsSpan(0, batchSize);
for (int i = 0; i < batchSize; i++)
{
divisorDataSpan[i] = CreateMontgomeryDivisorData(divisorSpan[i]);
}
for (int i = 0; i < batchSize; i++)
{
hitsSpan[i] = CheckDivisor(prime, useCycles, divisorSpan[i], divisorDataSpan[i]);
if (hitsSpan[i] != 0)
{
composite = true;
lastProcessed = divisorSpan[i];
break;
}
}
if (!composite)
{
lastProcessed = divisorSpan[batchSize - 1];
}
if (composite)
{
break;
}
if (reachedEndInBatch)
{
processedAll = true;
break;
}
}
processedAll = processedAll || divisor > allowedMax;
return composite;
}
private static byte CheckDivisor(ulong prime, bool useCycles, ulong divisor, in MontgomeryDivisorData divisorData)
{
ulong modulus = divisorData.Modulus;
if (modulus <= 1UL || (modulus & 1UL) == 0UL)
{
return 0;
}
ulong exponent = prime;
if (useCycles)
{
ulong cycle = MersenneDivisorCycles.CalculateCycleLength(divisor);
if (cycle == 0UL)
{
return 0;
}
ulong remainder = prime % cycle;
if (remainder != 0UL)
{
return 0;
}
exponent = remainder;
}
return exponent.Pow2MontgomeryMod(divisorData) == 1UL ? (byte)1 : (byte)0;
}
private void UpdateStatusUnsafe(ulong lastProcessed, ulong processedCount)
{
if (processedCount == 0UL)
{
return;
}
ulong interval = PerfectNumberConstants.ConsoleInterval;
if (interval == 0UL)
{
_lastStatusDivisor = 0UL;
return;
}
ulong total = _lastStatusDivisor + processedCount;
_lastStatusDivisor = total % interval;
}
private static ulong ComputeDivisorLimitFromMaxPrime(ulong maxPrime)
{
if (maxPrime <= 1UL)
{
return 0UL;
}
if (maxPrime - 1UL >= 64UL)
{
return ulong.MaxValue;
}
return (1UL << (int)(maxPrime - 1UL)) - 1UL;
}
private static ulong ComputeAllowedMaxDivisor(ulong prime, ulong divisorLimit)
{
if (prime <= 1UL)
{
return 0UL;
}
if (prime - 1UL >= 64UL)
{
return divisorLimit;
}
return Math.Min((1UL << (int)(prime - 1UL)) - 1UL, divisorLimit);
}
private static MontgomeryDivisorData CreateMontgomeryDivisorData(ulong modulus)
{
if (modulus <= 1UL || (modulus & 1UL) == 0UL)
{
return new MontgomeryDivisorData(modulus, 0UL, 0UL, 0UL);
}
return new MontgomeryDivisorData(
modulus,
ComputeMontgomeryNPrime(modulus),
ComputeMontgomeryResidue(1UL, modulus),
ComputeMontgomeryResidue(2UL, modulus));
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static ulong ComputeMontgomeryResidue(ulong value, ulong modulus) => (ulong)((UInt128)value * (UInt128.One << 64) % modulus);
private static ulong ComputeMontgomeryNPrime(ulong modulus)
{
ulong inv = modulus;
inv *= unchecked(2UL - modulus * inv);
inv *= unchecked(2UL - modulus * inv);
inv *= unchecked(2UL - modulus * inv);
inv *= unchecked(2UL - modulus * inv);
inv *= unchecked(2UL - modulus * inv);
inv *= unchecked(2UL - modulus * inv);
return unchecked(0UL - inv);
}
private sealed class DivisorScanSession : IMersenneNumberDivisorByDivisorTester.IDivisorScanSession
{
private readonly MersenneNumberDivisorByDivisorCpuTester _owner;
private ulong[] _primeBuffer;
private int[] _positionBuffer;
private ulong[] _exponentBuffer;
private int _capacity;
private bool _disposed;
internal DivisorScanSession(MersenneNumberDivisorByDivisorCpuTester owner)
{
_owner = owner;
_capacity = Math.Max(1, owner._batchSize);
_primeBuffer = ArrayPool<ulong>.Shared.Rent(_capacity);
_positionBuffer = ArrayPool<int>.Shared.Rent(_capacity);
_exponentBuffer = ArrayPool<ulong>.Shared.Rent(_capacity);
}
internal void Reset()
{
_disposed = false;
}
public void CheckDivisor(ulong divisor, ulong divisorCycle, ReadOnlySpan<ulong> primes, Span<byte> hits)
{
if (_disposed)
{
throw new ObjectDisposedException(nameof(DivisorScanSession));
}
int primesLength = primes.Length;
if (primesLength == 0)
{
return;
}
MersenneNumberDivisorByDivisorCpuTester owner = _owner;
int batchSize = owner._batchSize;
EnsureCapacity(batchSize);
ulong modulus = divisor;
if (modulus <= 1UL || (modulus & 1UL) == 0UL)
{
return;
}
bool cycleEnabled = owner._useDivisorCycles && divisorCycle != 0UL;
ulong cycle = divisorCycle;
MontgomeryDivisorData divisorData = CreateMontgomeryDivisorData(divisor);
int offset = 0;
Span<ulong> primeSpan = _primeBuffer.AsSpan();
Span<int> positionSpan = _positionBuffer.AsSpan();
Span<ulong> exponentSpan = _exponentBuffer.AsSpan();
ulong previousResidue = 0UL;
ulong previousPrime = 0UL;
bool hasPreviousResidue = false;
while (offset < primesLength)
{
int sliceLength = Math.Min(batchSize, primesLength - offset);
ReadOnlySpan<ulong> primesSlice = primes.Slice(offset, sliceLength);
Span<byte> hitsSlice = hits.Slice(offset, sliceLength);
hitsSlice.Clear();
int computeCount = 0;
if (cycleEnabled)
{
for (int i = 0; i < sliceLength; i++)
{
ulong prime = primesSlice[i];
if (prime % cycle != 0UL)
{
continue;
}
primeSpan[computeCount] = prime;
positionSpan[computeCount] = i;
computeCount++;
}
}
else
{
for (int i = 0; i < sliceLength; i++)
{
primeSpan[computeCount] = primesSlice[i];
positionSpan[computeCount] = i;
computeCount++;
}
}
if (computeCount > 0)
{
Span<ulong> exponentSlice = exponentSpan[..computeCount];
ulong currentPrime = hasPreviousResidue ? previousPrime : 0UL;
bool hasDeltaSource = hasPreviousResidue;
for (int i = 0; i < computeCount; i++)
{
ulong prime = primeSpan[i];
ulong exponentValue;
if (hasDeltaSource)
{
exponentValue = prime - currentPrime;
}
else
{
exponentValue = prime;
hasDeltaSource = true;
}
if (cycleEnabled)
{
exponentValue %= cycle;
}
exponentSlice[i] = exponentValue;
currentPrime = prime;
}
for (int i = 0; i < computeCount; i++)
{
exponentSlice[i] = exponentSlice[i].Pow2MontgomeryMod(divisorData);
}
for (int i = 0; i < computeCount; i++)
{
int position = positionSpan[i];
ulong stepResidue = exponentSlice[i];
ulong prime = primeSpan[i];
ulong residue = hasPreviousResidue ? MultiplyMod(previousResidue, stepResidue, modulus) : stepResidue;
hitsSlice[position] = residue == 1UL ? (byte)1 : (byte)0;
previousResidue = residue;
previousPrime = prime;
hasPreviousResidue = true;
}
}
offset += sliceLength;
}
}
public void Dispose()
{
if (_disposed)
{
return;
}
_disposed = true;
_owner.ReturnSession(this);
}
private void EnsureCapacity(int requiredCapacity)
{
if (requiredCapacity <= _capacity)
{
return;
}
ArrayPool<ulong>.Shared.Return(_primeBuffer, clearArray: false);
ArrayPool<int>.Shared.Return(_positionBuffer, clearArray: false);
ArrayPool<ulong>.Shared.Return(_exponentBuffer, clearArray: false);
_capacity = requiredCapacity;
_primeBuffer = ArrayPool<ulong>.Shared.Rent(_capacity);
_positionBuffer = ArrayPool<int>.Shared.Rent(_capacity);
_exponentBuffer = ArrayPool<ulong>.Shared.Rent(_capacity);
}
private static ulong MultiplyMod(ulong left, ulong right, ulong modulus)
{
if (modulus == 0UL)
{
return 0UL;
}
UInt128 product = (UInt128)left * right;
return (ulong)(product % modulus);
}
}
}