[SL.Core] Merge pull request SixLabors/Core#24 from carbon/master

Downgrade System.Buffers and Remove HashHelpers

src/SixLabors.Core/Helpers/HashHelpers.cs

@@ -1,67 +0,0 @@
-// Copyright (c) Six Labors and contributors.
-// Licensed under the Apache License, Version 2.0.
-
-using System;
-
-namespace SixLabors
-{
-    /// <summary>
-    /// Provides a set of helpers for combining object hashes.
-    /// </summary>
-    internal static class HashHelpers
-    {
-        /// <summary>
-        /// Combines the two specified hash codes.
-        /// </summary>
-        /// <param name="h1">Hash code one</param>
-        /// <param name="h2">Hash code two</param>
-        /// <returns>Returns a hash code for the provided hash codes.</returns>
-        [Obsolete("Use HashCode.Combine instead")]
-        public static int Combine(int h1, int h2)
-        {
-            // Lifted from coreFX repo
-            unchecked
-            {
-                // RyuJIT optimizes this to use the ROL instruction
-                // Related GitHub pull request: dotnet/coreclr#1830
-                uint rol5 = ((uint)h1 << 5) | ((uint)h1 >> 27);
-                return ((int)rol5 + h1) ^ h2;
-            }
-        }
-
-        /// <summary>
-        /// Combines the three specified hash codes.
-        /// </summary>
-        /// <param name="h1">The first </param>
-        /// <param name="h2">Hash code two</param>
-        /// <param name="h3">Hash code three</param>
-        /// <returns>Returns a hash code for the provided hash codes.</returns>
-        [Obsolete("Use HashCode.Combine instead")]
-        public static int Combine(int h1, int h2, int h3)
-        {
-            int hash = Combine(h1, h2);
-
-            hash = Combine(hash, h3);
-
-            return hash;
-        }
-
-        /// <summary>
-        /// Combines the four specified hash codes.
-        /// </summary>
-        /// <param name="h1">The first </param>
-        /// <param name="h2">Hash code two</param>
-        /// <param name="h3">Hash code three</param>
-        /// <param name="h4">Hash code four</param>
-        /// <returns>Returns a hash code for the provided hash codes.</returns>
-        [Obsolete("Use HashCode.Combine instead")]
-        public static int Combine(int h1, int h2, int h3, int h4)
-        {
-            int hash = Combine(h1, h2);
-
-            hash = Combine(hash, h3);
-
-            return Combine(hash, h4);
-        }
-    }
-}

src/SixLabors.Core/SixLabors.Core.csproj

@@ -48,7 +48,7 @@
     </ItemGroup>  
 
     <ItemGroup Condition=" '$(TargetFramework)' != 'netcoreapp2.1' ">
-        <PackageReference Include="System.Buffers" Version="4.5.0" />
+        <PackageReference Include="System.Buffers" Version="4.4.0" />
         <PackageReference Include="System.Memory" Version="4.5.1" />
     </ItemGroup>
 

tests/SixLabors.Core.Tests/Helpers/HashHelpersTests.cs

@@ -1,28 +0,0 @@
-// Copyright (c) Six Labors and contributors.
-// Licensed under the Apache License, Version 2.0.
-
-using Xunit;
-
-namespace SixLabors.Tests.Helpers
-{
-    public class HashHelpersTests
-    {
-        [Fact]
-        public void CanCombineTwoValues()
-        {
-            Assert.Equal(35, HashHelpers.Combine(1, 2));
-        }
-
-        [Fact]
-        public void CanCombineThreeValues()
-        {
-            Assert.Equal(1152, HashHelpers.Combine(1, 2, 3));
-        }
-
-        [Fact]
-        public void CanCombineFourValues()
-        {
-            Assert.Equal(38020, HashHelpers.Combine(1, 2, 3, 4));
-        }
-    }
-}