Add xxHash32 hasher class (nw)

Author: mnadareski

SabreTools.Hashing/XxHash/XxHash32.cs

@@ -0,0 +1,50 @@
+using System;
+
+namespace SabreTools.Hashing.XxHash
+{
+    internal class XxHash32
+    {
+        /// <summary>
+        /// The 32-bit seed to alter the hash result predictably.
+        /// </summary>
+        private uint _seed;
+
+        /// <summary>
+        /// Internal xxHash32 state
+        /// </summary>
+        private readonly XXH32State _state;
+
+        public XxHash32(uint seed = 0)
+        {
+            _seed = seed;
+            _state = new XXH32State();
+            _state.Reset(seed);
+        }
+
+        /// <summary>
+        /// Reset the internal hashing state
+        /// </summary>
+        public void Reset()
+        {
+            _state.Reset(_seed);
+        }
+
+        /// <summary>
+        /// Hash a block of data and append it to the existing hash
+        /// </summary>
+        /// <param name="data">Byte array representing the data</param>
+        /// <param name="offset">Offset in the byte array to include</param>
+        /// <param name="length">Length of the data to hash</param>
+        public void TransformBlock(byte[] data, int offset, int length)
+            => _state.Update(data, offset, length);
+
+        /// <summary>
+        /// Finalize the hash and return as a byte array
+        /// </summary>
+        public byte[] Finalize()
+        {
+            uint hash = _state.Digest();
+            return BitConverter.GetBytes(hash);
+        }
+    }
+}