mlemanczyk/even-perfect-numbers-scanner
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Various micro- and medium- optimizations

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Marek Lemańczyk committed 2025-10-07 22:14:34 +02:00
1 parent 2eb622030e
commit cd1debe9d6
25 files changed
+4403 -3210
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PerfectNumbers.Core/MontgomeryDivisorData.cs
+24 -23
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@@ -14,29 +14,6 @@ public readonly struct MontgomeryDivisorData(ulong modulus, ulong nPrime, ulong
public readonly ulong MontgomeryTwo = montgomeryTwo;
public readonly ulong MontgomeryTwoSquared = montgomeryTwoSquared;
}
internal static class MontgomeryDivisorDataCache
{
private static readonly ConcurrentDictionary<ulong, MontgomeryDivisorData> Cache = new();
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static MontgomeryDivisorData Get(ulong modulus) => Cache.GetOrAdd(modulus, static m => Create(m));
private static MontgomeryDivisorData Create(ulong modulus)
{
ulong nPrime = ComputeMontgomeryNPrime(modulus);
ulong montgomeryOne = ComputeMontgomeryResidue(UInt128Numbers.OneShiftedLeft64, modulus);
ulong montgomeryTwo = ComputeMontgomeryResidue(UInt128Numbers.OneShiftedLeft64x2, modulus);
ulong montgomeryTwoSquared = ULongExtensions.MontgomeryMultiply(montgomeryTwo, montgomeryTwo, modulus, nPrime);
return new MontgomeryDivisorData(
modulus,
nPrime,
montgomeryOne,
montgomeryTwo,
montgomeryTwoSquared);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static ulong ComputeMontgomeryResidue(UInt128 value, ulong modulus) => (ulong)(value % modulus);
@@ -53,4 +30,28 @@ internal static class MontgomeryDivisorDataCache
inv *= unchecked(2UL - modulus * inv);
return unchecked(0UL - inv);
}
public static MontgomeryDivisorData FromModulus(ulong modulus)
{
ulong nPrime = ComputeMontgomeryNPrime(modulus);
ulong montgomeryOne = ComputeMontgomeryResidue(UInt128Numbers.OneShiftedLeft64, modulus);
ulong montgomeryTwo = ComputeMontgomeryResidue(UInt128Numbers.OneShiftedLeft64x2, modulus);
ulong montgomeryTwoSquared = ULongExtensions.MontgomeryMultiply(montgomeryTwo, montgomeryTwo, modulus, nPrime);
return new MontgomeryDivisorData(
modulus,
nPrime,
montgomeryOne,
montgomeryTwo,
montgomeryTwoSquared);
}
}
internal static class MontgomeryDivisorDataCache
{
private static readonly ConcurrentDictionary<ulong, MontgomeryDivisorData> Cache = new();
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static MontgomeryDivisorData Get(ulong modulus) => Cache.GetOrAdd(modulus, static m => MontgomeryDivisorData.FromModulus(m));
}