From 9e3b592fa3636cf3d50460e303173de55bcb3920 Mon Sep 17 00:00:00 2001
From: Dahlia Trimble
Date: Wed, 3 Jun 2009 08:41:08 +0000
Subject: Thank you Imaze Rhiano for a patch that implements Cenome Memory
 Asset Cache (Mantis #3759) See the files:
 bin/config-include/GridCommon.ini.example and
 bin/config-include/StandaloneCommon.ini.example to configure and enable this
 caching method.

---
 OpenSim/Framework/PrimeNumberHelper.cs | 98 ++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 OpenSim/Framework/PrimeNumberHelper.cs

(limited to 'OpenSim/Framework/PrimeNumberHelper.cs')

diff --git a/OpenSim/Framework/PrimeNumberHelper.cs b/OpenSim/Framework/PrimeNumberHelper.cs
new file mode 100644
index 0000000..e4bf615
--- /dev/null
+++ b/OpenSim/Framework/PrimeNumberHelper.cs
@@ -0,0 +1,98 @@
+// --------------------------------------------------------------------------------------------------------------------
+// <copyright company="" file="PrimeNumberHelper.cs">
+//   
+// </copyright>
+// <summary>
+//   
+// </summary>
+// 
+// --------------------------------------------------------------------------------------------------------------------
+
+using System;
+
+namespace OpenSim.Framework
+{
+    /// <summary>
+    /// Utility class that is used to find small prime numbers and test is number prime number.
+    /// </summary>
+    public static class PrimeNumberHelper
+    {
+        /// <summary>
+        /// Precalculated prime numbers. 
+        /// </summary>
+        private static readonly int[] Primes = new int[]
+                                                   {
+                                                       3, 7, 11, 17, 23, 29, 37, 47, 59, 71, 89, 107, 131, 163, 197, 239,
+                                                       293, 353, 431, 521, 631, 761, 919, 1103, 1327, 1597, 1931, 2333,
+                                                       2801, 3371, 4049, 4861, 5839, 7013, 8419, 10103, 12143, 14591,
+                                                       17519, 21023, 25229, 30293, 36353, 43627, 52361, 62851, 75431,
+                                                       90523, 108631, 130363, 156437, 187751, 225307, 270371, 324449,
+                                                       389357, 467237, 560689, 672827, 807403, 968897, 1162687, 1395263,
+                                                       1674319, 2009191, 2411033, 2893249, 3471899, 4166287, 4999559,
+                                                       5999471, 7199369
+                                                   };
+
+        /// <summary>
+        /// Get prime number that is equal or larger than <see cref="min"/>.
+        /// </summary>
+        /// <param name="min">
+        /// Minimal returned prime number.
+        /// </param>
+        /// <returns>
+        /// Primer number that is equal or larger than <see cref="min"/>. If <see cref="min"/> is too large, return -1.
+        /// </returns>
+        public static int GetPrime( int min )
+        {
+            if( min <= 2 )
+                return 2;
+
+            if( Primes[ Primes.Length - 1 ] < min )
+            {
+                for( int i = min | 1 ; i < 0x7FFFFFFF ; i += 2 )
+                {
+                    if( IsPrime( i ) )
+                        return i;
+                }
+
+                return -1;
+            }
+
+            for( int i = Primes.Length - 2 ; i >= 0 ; i-- )
+            {
+                if( min == Primes[ i ] )
+                    return min;
+
+                if( min > Primes[ i ] )
+                    return Primes[ i + 1 ];
+            }
+
+            return 2;
+        }
+
+        /// <summary>
+        /// Just basic Sieve of Eratosthenes prime number test.
+        /// </summary>
+        /// <param name="candinate">
+        /// Number that is tested.
+        /// </param>
+        /// <returns>
+        /// true, if <see cref="candinate"/> is prime number; otherwise false.
+        /// </returns>
+        public static bool IsPrime( int candinate )
+        {
+            if( (candinate & 1) == 0 )
+
+                // Even number - only prime if 2
+                return candinate == 2;
+
+            int upperBound = (int) Math.Sqrt( candinate );
+            for( int i = 3 ; i < upperBound ; i += 2 )
+            {
+                if( candinate % i == 0 )
+                    return false;
+            }
+
+            return true;
+        }
+    }
+}
-- 
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