optimize

more optimal algorithm

Author: darrenkopp

MurmurHash/Managed/Murmur32ManagedX86.cs

@@ -25,28 +25,23 @@ protected override void HashCore(byte[] array, int ibStart, int cbSize)
         {
             Length += cbSize;
             if (cbSize > 0)
-            {
-                var blocks = (cbSize / 4);
-                var remainder = (cbSize & 3);
-
-                Body(array, ibStart, blocks, remainder);
-            }
+                Body(array, ibStart, cbSize);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void Body(byte[] data, int offset, int blocks, int remainder)
+        private void Body(byte[] data, int start, int length)
         {
-            // grab reference to the end of our data as uint blocks
-            while (blocks-- > 0)
-            {
-                // get our values
-                uint k1 = BitConverter.ToUInt32(data, offset); offset += 4;
+            int remainder = length & 3;
+            int alignedLength = start + (length - remainder);
 
+            for (int i = start; i < alignedLength; i += 4)
+            {
+                uint k1 = BitConverter.ToUInt32(data, i);
                 H1 = (((H1 ^ (((k1 * C1).RotateLeft(15)) * C2)).RotateLeft(13)) * 5) + 0xe6546b64;
             }
 
             if (remainder > 0)
-                Tail(data, offset, remainder);
+                Tail(data, alignedLength, remainder);
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -58,9 +53,9 @@ private void Tail(byte[] tail, int position, int remainder)
             // determine how many bytes we have left to work with based on length
             switch (remainder)
             {
-                case 3: k1 ^= (uint)tail[position + 2] << 16;   goto case 2;
-                case 2: k1 ^= (uint)tail[position + 1] << 8;    goto case 1;
-                case 1: k1 ^= tail[position];                   break;
+                case 3: k1 ^= (uint)tail[position + 2] << 16; goto case 2;
+                case 2: k1 ^= (uint)tail[position + 1] << 8; goto case 1;
+                case 1: k1 ^= tail[position]; break;
             }
 
             H1 = H1 ^ ((k1 * C1).RotateLeft(15) * C2);