Allocate unique p ranges per thread

EvenPerfectBitScanner/Program.cs

@@ -599,13 +599,7 @@ internal static class Program
                                 ulong[] buffer = new ulong[blockSize];
                                 while (!Volatile.Read(ref _limitReached))
                                 {
-					int count = 0;
+                                        int count = ReserveBlock(buffer, blockSize);
-					while (count < blockSize && !Volatile.Read(ref _limitReached))
-					{
-						buffer[count] = ReserveNextP();
-						count++;
-					}
-
                                         if (count == 0)
                                         {
                                                 break;
@@ -623,7 +617,7 @@ internal static class Program
                                                         Console.WriteLine($"Testing {p}");
                                                 }
 
-						bool isPerfect = IsEvenPerfectCandidate(p, out bool searchedMersenne, out bool detailedCheck);
+                                                bool isPerfect = IsEvenPerfectCandidate(p, divisorCyclesSearchLimit, out bool searchedMersenne, out bool detailedCheck);
                                                 PrintResult(p, searchedMersenne, detailedCheck, isPerfect);
                                         }
                                 }
@@ -743,7 +737,7 @@ internal static class Program
 	}
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-	private static unsafe ulong ReserveNextP()
+        private static unsafe int ReserveBlock(ulong[] buffer, int blockSize)
         {
                 while (true)
                 {
@@ -751,12 +745,24 @@ internal static class Program
                         ulong current = (ulong)state >> 3;
                         ulong remainder = ((ulong)state) & 7UL;
 
-			ulong next = _transformP(current, ref remainder);
+                        ulong p = current;
-			long newState = ((long)next << 3) | (long)remainder;
+                        int count = 0;
+                        while (count < blockSize && !Volatile.Read(ref _limitReached))
+                        {
+                                buffer[count++] = p;
+                                p = _transformP(p, ref remainder);
+                        }
+
+                        if (count == 0)
+                        {
+                                return 0;
+                        }
+
+                        long newState = ((long)p << 3) | (long)remainder;
                         long original = Interlocked.CompareExchange(ref _state, newState, state);
                         if (original == state)
                         {
-				return current;
+                                return count;
                         }
                 }
         }
@@ -951,7 +957,7 @@ internal static class Program
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         internal static bool IsEvenPerfectCandidate(ulong p)
         {
-		return IsEvenPerfectCandidate(p, out _, out _);
+                return IsEvenPerfectCandidate(p, 0, out _, out _);
         }
 
 	internal static bool IsEvenPerfectCandidate(ulong p, int divisorCyclesSearchLimit, out bool searchedMersenne, out bool detailedCheck)