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Add optimized modulo helpers for unsigned integers

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Marek Lemańczyk committed 2025-09-21 10:14:26 +02:00
1 parent 2c2bc62cb2
commit 95a0b030f6
7 files changed
+425 -84
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PerfectNumbers.Core/ULongExtensions.cs
+114 -45
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@@ -58,51 +58,62 @@ public static class ULongExtensions
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void Mod10_8_5_3(this ulong value, out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3)
{
ulong temp = value;
uint byteSum = 0U;
public static void Mod10_8_5_3(this ulong value, out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3)
{
ulong temp = value;
uint byteSum = 0U;
do
{
byteSum += (byte)temp;
temp >>= 8;
}
while (temp != 0UL);
do
{
byteSum += (byte)temp;
temp >>= 8;
}
while (temp != 0UL);
mod8 = value & 7UL;
mod8 = value & 7UL;
uint mod5Value = PerfectNumbersMath.FastRemainder5(byteSum);
uint mod3Value = PerfectNumbersMath.FastRemainder3(byteSum);
uint mod5Value = PerfectNumbersMath.FastRemainder5(byteSum);
uint mod3Value = PerfectNumbersMath.FastRemainder3(byteSum);
ulong parity = mod8 & 1UL;
mod10 = parity == 0UL
? mod5Value switch
{
0U => 0UL,
1U => 6UL,
2U => 2UL,
3U => 8UL,
_ => 4UL,
}
: mod5Value switch
{
0U => 5UL,
1U => 1UL,
2U => 7UL,
3U => 3UL,
_ => 9UL,
};
ulong parity = mod8 & 1UL;
mod10 = parity == 0UL
? mod5Value switch
{
0U => 0UL,
1U => 6UL,
2U => 2UL,
3U => 8UL,
_ => 4UL,
}
: mod5Value switch
{
0U => 5UL,
1U => 1UL,
2U => 7UL,
3U => 3UL,
_ => 9UL,
};
mod5 = mod5Value;
mod3 = mod3Value;
}
mod5 = mod5Value;
mod3 = mod3Value;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool IsPrimeCandidate(this ulong n)
{
int i = 0;
ulong p;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static void Mod10_8_5_3Steps(this ulong value, out ulong step10, out ulong step8, out ulong step5, out ulong step3)
{
value.Mod10_8_5_3(out ulong mod10, out ulong mod8, out ulong mod5, out ulong mod3);
step10 = (mod10 << 1).Mod10();
step8 = ((mod8 << 1) & 7UL);
step5 = (mod5 << 1).Mod5();
step3 = (mod3 << 1).Mod3();
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static bool IsPrimeCandidate(this ulong n)
{
int i = 0;
ulong p;
uint[] smallPrimes = PrimesGenerator.SmallPrimes;
ulong[] smallPrimesPow2 = PrimesGenerator.SmallPrimesPow2;
int len = smallPrimes.Length;
@@ -123,12 +134,70 @@ public static class ULongExtensions
return true;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static ulong Mod10(this ulong value)
{
ulong quotient = (ulong)(((UInt128)value * 0xCCCCCCCCCCCCCCCDUL) >> 67);
return value - quotient * 10UL;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static ulong Mod10(this ulong value)
{
ulong quotient = (ulong)(((UInt128)value * 0xCCCCCCCCCCCCCCCDUL) >> 67);
return value - quotient * 10UL;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static ulong Mod8(this ulong value) => value & 7UL;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static ulong Mod3(this ulong value)
{
uint sum = (uint)(value & 0xFFFFUL);
sum += (uint)((value >> 16) & 0xFFFFUL);
sum += (uint)((value >> 32) & 0xFFFFUL);
sum += (uint)((value >> 48) & 0xFFFFUL);
return PerfectNumbersMath.FastRemainder3(sum);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static ulong Mod5(this ulong value)
{
uint sum = (uint)(value & 0xFFFFUL);
sum += (uint)((value >> 16) & 0xFFFFUL);
sum += (uint)((value >> 32) & 0xFFFFUL);
sum += (uint)((value >> 48) & 0xFFFFUL);
return PerfectNumbersMath.FastRemainder5(sum);
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static ulong Mod7(this ulong value)
{
uint low = (uint)value;
uint high = (uint)(value >> 32);
ulong remainder = low.Mod7() + (ulong)high.Mod7() * 4UL;
while (remainder >= 7UL)
{
remainder -= 7UL;
}
return remainder;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static ulong Mod11(this ulong value)
{
uint low = (uint)value;
uint high = (uint)(value >> 32);
ulong remainder = low.Mod11() + (ulong)high.Mod11() * 4UL;
while (remainder >= 11UL)
{
remainder -= 11UL;
}
return remainder;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static ulong Mod128(this ulong value) => value & 127UL;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static UInt128 Mul64(this ulong a, ulong b) => ((UInt128)a.MulHigh(b) << 64) | (UInt128)(a * b);