Merge pull request #42 from Valdas3/master

#37: add Fowler–Noll–Vo hash function with tests

Author: Rizzen

Algorithms/Algorithms.Tests/FowlerNollVoHashTests/FowlerNollVoHashTests.cs

@@ -0,0 +1,24 @@
+using System.Text;
+using Xunit;
+
+namespace Algorithms.Tests.FowlerNollVoHashTests
+{
+    // tests taken from http://www.isthe.com/chongo/src/fnv/test_fnv.c
+    public class FowlerNollVoHashTests
+    {
+        [Theory]
+        [InlineData("", 0x811c9dc5)]
+        [InlineData("a", 0x050c5d7e)]
+        [InlineData("b", 0x050c5d7d)]
+        [InlineData("foo", 0x408f5e13)]
+        [InlineData("foob", 0xb4b1178b)]
+        [InlineData("fooba", 0xfdc80fb0)]
+        [InlineData("foobar", 0x31f0b262)]
+        [InlineData("http://en.wikipedia.org/wiki/Fowler_Noll_Vo_hash", 0x025dfe59)]
+        public void Test(string input, uint expected)
+        {
+            var bytes = Encoding.UTF8.GetBytes(input);
+            Assert.Equal(expected, FowlerNollVoHash.FowlerNollVoHash.Hash(bytes));
+        }
+    }
+}

Algorithms/Algorithms/FowlerNollVoHash/FowlerNollVoHash.cs

@@ -0,0 +1,24 @@
+namespace Algorithms.FowlerNollVoHash
+{
+    public static class FowlerNollVoHash
+    {
+        private static uint _fnvPrime = 16777619;
+        private static uint _fnvOffset = 2166136261;
+        // FNV-1 hash variant for 32-bit hash
+        public static uint Hash(byte[] data)
+        {
+            if (data == null)
+            {
+                return 0;
+            }
+            var hash = _fnvOffset;
+            foreach (var b in data)
+            {
+                hash = hash * _fnvPrime;
+                hash = hash ^ b;
+            }
+
+            return hash;
+        }
+    }
+}