mlemanczyk/even-perfect-numbers-scanner
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Small refactoring

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Marek Lemańczyk committed 2025-09-21 09:32:01 +02:00
1 parent 412ce4fd50
commit 2c2bc62cb2
3 files changed
+80 -37
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PerfectNumbers.Core/ModuloAutomata.cs
+13 -36
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@@ -12,11 +12,11 @@ public sealed class MersenneResidueAutomaton
private readonly UInt128 _step; // 2*p
private UInt128 _currentQ; // current q value
// Cached residues for current q
public ulong Mod10R { get; private set; }
public ulong Mod8R { get; private set; }
public ulong Mod3R { get; private set; }
public ulong Mod5R { get; private set; }
// Cached residues for current q
public ulong Mod10R;
public ulong Mod8R;
public ulong Mod3R;
public ulong Mod5R;
// Cached residues for step (2*p mod m)
private readonly ulong _step10;
@@ -27,18 +27,18 @@ public sealed class MersenneResidueAutomaton
public MersenneResidueAutomaton(ulong exponent)
{
_step = (UInt128)exponent << 1; // 2 * p
_currentQ = _step + 1UL; // start at k = 1
_currentQ = _step + UInt128.One; // start at k = 1
// init residues
// init residues
Mod10R = _currentQ.Mod10();
Mod8R = Mod8(_currentQ);
Mod3R = Mod3(_currentQ);
Mod5R = Mod5(_currentQ);
Mod8R = _currentQ.Mod8();
Mod3R = _currentQ.Mod3();
Mod5R = _currentQ.Mod5();
_step10 = _step.Mod10().Mod10();
_step8 = (ulong)(_step & 7UL); // % 8
_step3 = Mod3(_step);
_step5 = Mod5(_step);
_step8 = _step.Mod8();
_step3 = _step.Mod3();
_step5 = _step.Mod5();
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -71,29 +71,6 @@ public sealed class MersenneResidueAutomaton
}
Mod5R = r5;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static ulong Mod8(UInt128 value) => (ulong)value & 7UL;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static ulong Mod3(UInt128 value)
{
// 2^64 ≡ 1 (mod 3)
ulong high = (ulong)(value >> 64);
ulong low = (ulong)value;
ulong rem = (low % 3UL) + (high % 3UL);
return rem >= 3UL ? rem - 3UL : rem;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static ulong Mod5(UInt128 value)
{
// 2^64 ≡ 1 (mod 5)
ulong high = (ulong)(value >> 64);
ulong low = (ulong)value;
ulong rem = (low % 5UL) + (high % 5UL);
return rem >= 5UL ? rem - 5UL : rem;
}
}
/// <summary>