From 3b8a10a20bd70ba37ec4d347f856b4d936a8cce2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Lema=C5=84czyk?= <marek@lemanczyk.eu>
Date: Mon, 22 Sep 2025 19:54:54 +0200
Subject: [PATCH] Inline single-use modulo helpers

---
 .../Cpu/MersenneNumberLucasLehmerCpuTester.cs | 24 +++++++--------
 PerfectNumbers.Core/PrimesGenerator.cs        | 30 +++++++++++--------
 PerfectNumbers.Core/UInt128Extensions.cs      |  6 ++--
 PerfectNumbers.Core/UIntExtensions.cs         |  3 +-
 PerfectNumbers.Core/ULongExtensions.cs        |  5 ++--
 5 files changed, 33 insertions(+), 35 deletions(-)

diff --git a/PerfectNumbers.Core/Cpu/MersenneNumberLucasLehmerCpuTester.cs b/PerfectNumbers.Core/Cpu/MersenneNumberLucasLehmerCpuTester.cs
index bbc5785..93dddb5 100644
--- a/PerfectNumbers.Core/Cpu/MersenneNumberLucasLehmerCpuTester.cs
+++ b/PerfectNumbers.Core/Cpu/MersenneNumberLucasLehmerCpuTester.cs
@@ -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;
 		}
diff --git a/PerfectNumbers.Core/PrimesGenerator.cs b/PerfectNumbers.Core/PrimesGenerator.cs
index 5714122..a51e555 100644
--- a/PerfectNumbers.Core/PrimesGenerator.cs
+++ b/PerfectNumbers.Core/PrimesGenerator.cs
@@ -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,
+                };
+        }
 }
diff --git a/PerfectNumbers.Core/UInt128Extensions.cs b/PerfectNumbers.Core/UInt128Extensions.cs
index ecfde88..904d84c 100644
--- a/PerfectNumbers.Core/UInt128Extensions.cs
+++ b/PerfectNumbers.Core/UInt128Extensions.cs
@@ -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;
 	}
-}
\ No newline at end of file
+}
diff --git a/PerfectNumbers.Core/UIntExtensions.cs b/PerfectNumbers.Core/UIntExtensions.cs
index a43e191..d17afa0 100644
--- a/PerfectNumbers.Core/UIntExtensions.cs
+++ b/PerfectNumbers.Core/UIntExtensions.cs
@@ -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)]
diff --git a/PerfectNumbers.Core/ULongExtensions.cs b/PerfectNumbers.Core/ULongExtensions.cs
index eea9e9f..a9f6837 100644
--- a/PerfectNumbers.Core/ULongExtensions.cs
+++ b/PerfectNumbers.Core/ULongExtensions.cs
@@ -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;
 	}
-}
\ No newline at end of file
+}