(ded4a3e0a) v0.9.0.7

2019-06-25 16:00:44 +03:00
parent e5ae622c77
commit 4a51db77b5
1777 changed files with 421528 additions and 917 deletions
@@ -0,0 +1,76 @@
+// MonoGame - Copyright (C) The MonoGame Team
+// This file is subject to the terms and conditions defined in
+// file 'LICENSE.txt', which is part of this source code package.
+
+using System.IO;
+
+namespace MonoGame.Utilities
+{
+    internal static class Hash
+    {
+        /// <summary>
+        /// Compute a hash from a byte array.
+        /// </summary>
+        /// <remarks>
+        /// Modified FNV Hash in C#
+        /// http://stackoverflow.com/a/468084
+        /// </remarks>
+        internal static int ComputeHash(params byte[] data)
+        {
+            unchecked
+            {
+                const int p = 16777619;
+                var hash = (int)2166136261;
+
+                for (var i = 0; i < data.Length; i++)
+                    hash = (hash ^ data[i]) * p;
+
+                hash += hash << 13;
+                hash ^= hash >> 7;
+                hash += hash << 3;
+                hash ^= hash >> 17;
+                hash += hash << 5;
+                return hash;
+            }
+        }
+        
+        /// <summary>
+        /// Compute a hash from the content of a stream and restore the position.
+        /// </summary>
+        /// <remarks>
+        /// Modified FNV Hash in C#
+        /// http://stackoverflow.com/a/468084
+        /// </remarks>
+        internal static int ComputeHash(Stream stream)
+        {
+            System.Diagnostics.Debug.Assert(stream.CanSeek);
+
+            unchecked
+            {
+                const int p = 16777619;
+                var hash = (int)2166136261;
+
+                var prevPosition = stream.Position;
+                stream.Position = 0;
+
+                var data = new byte[1024];
+                int length;
+                while((length = stream.Read(data, 0, data.Length)) != 0)
+                {
+                    for (var i = 0; i < length; i++)
+                        hash = (hash ^ data[i]) * p;
+                }
+
+                // Restore stream position.
+                stream.Position = prevPosition;
+
+                hash += hash << 13;
+                hash ^= hash >> 7;
+                hash += hash << 3;
+                hash ^= hash >> 17;
+                hash += hash << 5;
+                return hash;
+            }
+        }
+    }
+}