Inline single-use modulo helpers

This commit is contained in:
Marek Lemańczyk committed 2025-09-22 19:54:54 +02:00
1 parent 3598f88aaf
commit 3b8a10a20b
5 files changed
+33 -35

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@@ -4,20 +4,16 @@ public class MersenneNumberLucasLehmerCpuTester
{
public bool IsPrime(ulong exponent)
{
// Early rejections aligned with incremental/order sieves, but safe for small p:
// - If 3 | p and p != 3, then 7 | M_p -> composite.
// - If p ≡ 1 (mod 4) and p shares a factor with (p-1), reject fast.
// - If p is divisible by divisors specific to numbers ending with 1 or 7, reject fast.
ulong mod3 = exponent.Mod3();
ulong mod5 = exponent.Mod5();
ulong mod7 = exponent.Mod7();
ulong mod11 = exponent.Mod11();
if (
(mod3 == 0UL && exponent != 3UL) ||
(mod5 == 0UL && exponent != 5UL) ||
(mod7 == 0UL && exponent != 7UL) ||
(mod11 == 0UL && exponent != 11UL)
)
// Early rejections aligned with incremental/order sieves, but safe for small p:
// - If 3 | p and p != 3, then 7 | M_p -> composite.
// - If p ≡ 1 (mod 4) and p shares a factor with (p-1), reject fast.
// - If p is divisible by divisors specific to numbers ending with 1 or 7, reject fast.
if (
(exponent.Mod3() == 0UL && exponent != 3UL) ||
(exponent.Mod5() == 0UL && exponent != 5UL) ||
(exponent.Mod7() == 0UL && exponent != 7UL) ||
(exponent.Mod11() == 0UL && exponent != 11UL)
)
{
return false;
}
+18 -12
View File
@@ -97,17 +97,23 @@ public static class PrimesGenerator
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static bool IsAllowedForLastOne(uint prime)
{
uint mod10 = prime % 10U;
return mod10 == 1U || mod10 == 3U || mod10 == 9U || prime == 7U || prime == 11U;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static bool IsAllowedForLastOne(uint prime)
{
return (prime % 10U) switch
{
1U or 3U or 9U => true,
_ => prime == 7U || prime == 11U,
};
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static bool IsAllowedForLastSeven(uint prime)
{
uint mod10 = prime % 10U;
return mod10 == 3U || mod10 == 7U || mod10 == 9U || prime == 11U;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static bool IsAllowedForLastSeven(uint prime)
{
return (prime % 10U) switch
{
3U or 7U or 9U => true,
_ => prime == 11U,
};
}
}
+2 -4
View File
@@ -241,9 +241,7 @@ public static class UInt128Extensions
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static ulong Mod6(this UInt128 value)
{
ulong mod3 = value.Mod3();
ulong key = (mod3 << 1) | ((ulong)value & 1UL);
return key switch
return ((value.Mod3() << 1) | ((ulong)value & 1UL)) switch
{
0UL => 0UL,
1UL => 3UL,
@@ -318,4 +316,4 @@ public static class UInt128Extensions
return result;
}
}
}
+1 -2
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@@ -23,8 +23,7 @@ public static class UIntExtensions
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static uint Mod6(this uint value)
{
uint key = (value.Mod3() << 1) | (value & 1U);
return Mod6Lookup[(int)key];
return Mod6Lookup[(int)(((value.Mod3() << 1) | (value & 1U)))];
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
+2 -3
View File
@@ -221,8 +221,7 @@ public static class ULongExtensions
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static ulong Mod6(this ulong value)
{
ulong key = (value.Mod3() << 1) | (value & 1UL);
return Mod6Lookup[(int)key];
return Mod6Lookup[(int)(((value.Mod3() << 1) | (value & 1UL)))];
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -647,4 +646,4 @@ public static class ULongExtensions
return false;
}
}
}