47 lines
1.4 KiB
C#
47 lines
1.4 KiB
C#
using ILGPU;
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using ILGPU.Algorithms;
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namespace PerfectNumbers.Core.Gpu;
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internal static class DivisorKernels
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{
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public static void Kernel(Index1D _, ulong exponent, ReadOnlyGpuUInt128 divisor, ArrayView<byte> result)
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{
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if (divisor.High == 0UL && divisor.Low <= 1UL)
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{
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result[0] = 0;
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return;
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}
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GpuUInt128 baseVal;
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int x = divisor.High == 0UL
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? 63 - XMath.LeadingZeroCount(divisor.Low)
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: 127 - XMath.LeadingZeroCount(divisor.High);
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ReadOnlyGpuUInt128 readOnlyMod = divisor;
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if (x == 0)
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{
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baseVal = GpuUInt128.Pow2Mod(exponent, in readOnlyMod);
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result[0] = baseVal.High == 0UL && baseVal.Low == 1UL ? (byte)1 : (byte)0;
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return;
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}
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ulong ux = (ulong)x;
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if (x >= 64)
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{
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baseVal = new GpuUInt128(1UL << (x - 64), 0UL);
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}
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else
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{
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baseVal = new GpuUInt128(0UL, 1UL << x);
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}
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GpuUInt128 pow = baseVal;
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pow.ModPow(exponent / ux, in readOnlyMod);
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var part2 = GpuUInt128.Pow2Mod(exponent % ux, in readOnlyMod);
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GpuUInt128 product = pow;
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ReadOnlyGpuUInt128 part2ReadOnly = part2.AsReadOnly();
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product.MulMod(in part2ReadOnly, in readOnlyMod);
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result[0] = product.High == 0UL && product.Low == 1UL ? (byte)1 : (byte)0;
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}
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}
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