50 lines
1.3 KiB
C#
50 lines
1.3 KiB
C#
using ILGPU;
|
|
using ILGPU.Runtime;
|
|
|
|
namespace PerfectNumbers.Core.Gpu;
|
|
|
|
internal static class OrderKernels
|
|
{
|
|
public static void OrderKernelScan(
|
|
Index1D index,
|
|
ulong exponent,
|
|
ulong divMul,
|
|
ArrayView<GpuUInt128> qs,
|
|
ArrayView<ulong> orders)
|
|
{
|
|
GpuUInt128 q = qs[index];
|
|
ReadOnlyGpuUInt128 readOnlyQ = q.AsReadOnly();
|
|
GpuUInt128 phi = q - GpuUInt128.One;
|
|
if (phi.High != 0UL)
|
|
{
|
|
orders[index] = 0UL;
|
|
return;
|
|
}
|
|
|
|
ulong phi64 = phi.Low;
|
|
GpuUInt128 pow = GpuUInt128.Pow2Mod(phi64, in readOnlyQ);
|
|
if (pow != GpuUInt128.One)
|
|
{
|
|
orders[index] = 0UL;
|
|
return;
|
|
}
|
|
|
|
GpuUInt128 halfPow = GpuUInt128.Pow2Mod(phi64 >> 1, in readOnlyQ) - GpuUInt128.One;
|
|
if (GpuUInt128.BinaryGcd(halfPow, q) != GpuUInt128.One)
|
|
{
|
|
orders[index] = 0UL;
|
|
return;
|
|
}
|
|
|
|
ulong div = KernelMathHelpers.FastDiv64Gpu(phi64, exponent, divMul);
|
|
GpuUInt128 divPow = GpuUInt128.Pow2Mod(div, in readOnlyQ) - GpuUInt128.One;
|
|
if (GpuUInt128.BinaryGcd(divPow, q) != GpuUInt128.One)
|
|
{
|
|
orders[index] = 0UL;
|
|
return;
|
|
}
|
|
|
|
orders[index] = exponent;
|
|
}
|
|
}
|