Add Highest/LowestOneBit methods

2 files changed, 55 insertions, 0 deletions

diff --git a/crypto/src/util/Integers.cs b/crypto/src/util/Integers.cs
index efa437e17..00fb957aa 100644
--- a/crypto/src/util/Integers.cs
+++ b/crypto/src/util/Integers.cs
@@ -13,6 +13,33 @@ namespace Org.BouncyCastle.Utilities
             0x1F, 0x00, 0x1B, 0x01, 0x1C, 0x0D, 0x17, 0x02, 0x1D, 0x15, 0x13, 0x0E, 0x18, 0x10, 0x03, 0x07,
             0x1E, 0x1A, 0x0C, 0x16, 0x14, 0x12, 0x0F, 0x06, 0x19, 0x0B, 0x11, 0x05, 0x0A, 0x04, 0x09, 0x08 };
 
+        public static int HighestOneBit(int i)
+        {
+            return (int)HighestOneBit((uint)i);
+        }
+
+        [CLSCompliantAttribute(false)]
+        public static uint HighestOneBit(uint i)
+        {
+            i |= i >>  1;
+            i |= i >>  2;
+            i |= i >>  4;
+            i |= i >>  8;
+            i |= i >> 16;
+            return i - (i >> 1);
+        }
+
+        public static int LowestOneBit(int i)
+        {
+            return i & -i;
+        }
+
+        [CLSCompliantAttribute(false)]
+        public static uint LowestOneBit(uint i)
+        {
+            return (uint)LowestOneBit((int)i);
+        }
+
         public static int NumberOfLeadingZeros(int i)
         {
             if (i <= 0)
diff --git a/crypto/src/util/Longs.cs b/crypto/src/util/Longs.cs
index 4d675bdba..a2d7dde0f 100644
--- a/crypto/src/util/Longs.cs
+++ b/crypto/src/util/Longs.cs
@@ -15,6 +15,34 @@ namespace Org.BouncyCastle.Utilities
             0x3E, 0x33, 0x05, 0x19, 0x24, 0x27, 0x20, 0x2E, 0x3C, 0x2C, 0x2A, 0x14, 0x16, 0x39, 0x10, 0x09,
             0x32, 0x18, 0x23, 0x1F, 0x3B, 0x13, 0x38, 0x0F, 0x31, 0x1E, 0x12, 0x0E, 0x1D, 0x0D, 0x0C, 0x0B };
 
+        public static long HighestOneBit(long i)
+        {
+            return (long)HighestOneBit((ulong)i);
+        }
+
+        [CLSCompliantAttribute(false)]
+        public static ulong HighestOneBit(ulong i)
+        {
+            i |= i >>  1;
+            i |= i >>  2;
+            i |= i >>  4;
+            i |= i >>  8;
+            i |= i >> 16;
+            i |= i >> 32;
+            return i - (i >> 1);
+        }
+
+        public static long LowestOneBit(long i)
+        {
+            return i & -i;
+        }
+
+        [CLSCompliantAttribute(false)]
+        public static ulong LowestOneBit(ulong i)
+        {
+            return (ulong)LowestOneBit((long)i);
+        }
+
         public static int NumberOfLeadingZeros(long i)
         {
             int x = (int)(i >> 32), n = 0;