93 lines
2.4 KiB
C#
93 lines
2.4 KiB
C#
using PerfectNumbers.Core.Gpu.Accelerators;
|
|
|
|
namespace PerfectNumbers.Core.Cpu;
|
|
|
|
public class MersenneNumberIncrementalCpuTester(GpuKernelType kernelType)
|
|
{
|
|
private static readonly MersenneDivisorCyclesCpu _cycles = MersenneDivisorCyclesCpu.Shared;
|
|
private readonly GpuKernelType _kernelType = kernelType;
|
|
|
|
public void Scan(PrimeOrderCalculatorAccelerator gpu, ulong exponent, UInt128 twoP, LastDigit lastDigit, UInt128 maxK, ref bool isPrime)
|
|
{
|
|
UInt128 k = UInt128.One;
|
|
UInt128 one = k;
|
|
ulong divMul = (ulong)((((UInt128)1 << 64) - UInt128.One) / exponent) + 1UL;
|
|
// Use residue automaton always on CPU
|
|
var auto = new MersenneResidueAutomaton(exponent);
|
|
|
|
bool reject;
|
|
bool shouldCheck;
|
|
UInt128 q = auto.CurrentQ();
|
|
UInt128 divPow;
|
|
UInt128 halfPow;
|
|
UInt128 phi;
|
|
UInt128 qCycle;
|
|
|
|
ulong div;
|
|
ulong mod8;
|
|
ulong phi64;
|
|
|
|
while (k <= maxK && Volatile.Read(ref isPrime))
|
|
{
|
|
// TODO: Replace this direct GetCycle call with DivisorCycleCache.Lookup so we reuse the single snapshot block
|
|
// and compute missing cycles on the configured device without queuing additional block generation.
|
|
qCycle = MersenneDivisorCyclesCpu.GetCycle(q);
|
|
shouldCheck = auto.Mod10R != 5UL;
|
|
if (shouldCheck)
|
|
{
|
|
mod8 = auto.Mod8R;
|
|
if (mod8 != 1UL && mod8 != 7UL)
|
|
{
|
|
shouldCheck = false;
|
|
}
|
|
else if (auto.Mod3R == 0UL || auto.Mod5R == 0UL)
|
|
{
|
|
// TODO: Swap these Mod3/Mod5 zero checks to the cached residue tables once the automaton exposes
|
|
// the benchmarked lookup-based helpers so CPU scans avoid runtime modulo instructions.
|
|
shouldCheck = false;
|
|
}
|
|
}
|
|
|
|
if (shouldCheck)
|
|
{
|
|
if (_kernelType == GpuKernelType.Pow2Mod)
|
|
{
|
|
reject = exponent.PowModWithCycle(q, qCycle) == UInt128.One;
|
|
}
|
|
else
|
|
{
|
|
phi = q - one;
|
|
reject = false;
|
|
if (phi <= ulong.MaxValue)
|
|
{
|
|
phi64 = (ulong)phi;
|
|
if (phi64.PowModWithCycle(q, qCycle) == one)
|
|
{
|
|
halfPow = (phi64 >> 1).PowModWithCycle(q, qCycle) - one;
|
|
if (halfPow.BinaryGcd(q) == one)
|
|
{
|
|
div = phi64.FastDiv64(exponent, divMul);
|
|
divPow = div.PowModWithCycle(q, qCycle) - one;
|
|
if (divPow.BinaryGcd(q) == one)
|
|
{
|
|
reject = true;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (reject && q.IsPrimeCandidate())
|
|
{
|
|
Volatile.Write(ref isPrime, false);
|
|
break;
|
|
}
|
|
}
|
|
|
|
k += 1UL;
|
|
auto.Next();
|
|
q = auto.CurrentQ();
|
|
}
|
|
}
|
|
}
|