Use Numerics class as polyfill for BitOperations

src/ImageSharp/Common/Helpers/BitOperations.cs

@@ -1,26 +0,0 @@
-// Copyright (c) Six Labors.
-// Licensed under the Apache License, Version 2.0.
-
-using System.Runtime.CompilerServices;
-
-#if !NETCOREAPP3_1_OR_GREATER
-namespace SixLabors.ImageSharp.Common.Helpers
-{
-    /// <summary>
-    /// Polyfill for System.Numerics.BitOperations class, introduced in .NET Core 3.0.
-    /// <see href="https://github.com/dotnet/runtime/blob/main/src/libraries/System.Private.CoreLib/src/System/Numerics/BitOperations.cs"/>
-    /// </summary>
-    public static class BitOperations
-    {
-        /// <summary>
-        /// Rotates the specified value left by the specified number of bits.
-        /// </summary>
-        /// <param name="value">The value to rotate.</param>
-        /// <param name="offset">The number of bits to roate with.</param>
-        /// <returns>The rotated value.</returns>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public static uint RotateLeft(uint value, int offset)
-            => (value << offset) | (value >> (32 - offset));
-    }
-}
-#endif

src/ImageSharp/Common/Helpers/Numerics.cs

@@ -907,5 +907,33 @@ namespace SixLabors.ImageSharp
         /// <param name="divisor">Divisor value.</param>
         /// <returns>Ceiled division result.</returns>
         public static uint DivideCeil(uint value, uint divisor) => (value + divisor - 1) / divisor;
+
+        /// <summary>
+        /// Rotates the specified value left by the specified number of bits.
+        /// </summary>
+        /// <param name="value">The value to rotate.</param>
+        /// <param name="offset">The number of bits to roate with.</param>
+        /// <returns>The rotated value.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static uint RotateLeft(uint value, int offset)
+        {
+#if SUPPORTS_BITOPERATIONS
+            return BitOperations.RotateLeft(value, offset);
+#else
+            return RotateLeftSoftwareFallback(value, offset);
+#endif
+        }
+
+#if !SUPPORTS_BITOPERATIONS
+        /// <summary>
+        /// Rotates the specified value left by the specified number of bits.
+        /// </summary>
+        /// <param name="value">The value to rotate.</param>
+        /// <param name="offset">The number of bits to roate with.</param>
+        /// <returns>The rotated value.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static uint RotateLeftSoftwareFallback(uint value, int offset)
+            => (value << offset) | (value >> (32 - offset));
+#endif
     }
 }

src/ImageSharp/Common/Helpers/Shuffle/IComponentShuffle.cs

@@ -190,7 +190,7 @@ namespace SixLabors.ImageSharp
                 // tmp1 + tmp3         = [W X Y Z]
                 uint tmp1 = packed & 0xFF00FF00;
                 uint tmp2 = packed & 0x00FF00FF;
-                uint tmp3 = BitOperations.RotateLeft(tmp2, 16);
+                uint tmp3 = Numerics.RotateLeft(tmp2, 16);
 
                 Unsafe.Add(ref dBase, i) = tmp1 + tmp3;
             }
@@ -223,7 +223,7 @@ namespace SixLabors.ImageSharp
                 // tmp1 + tmp3         = [Y Z W X]
                 uint tmp1 = packed & 0x00FF00FF;
                 uint tmp2 = packed & 0xFF00FF00;
-                uint tmp3 = BitOperations.RotateLeft(tmp2, 16);
+                uint tmp3 = Numerics.RotateLeft(tmp2, 16);
 
                 Unsafe.Add(ref dBase, i) = tmp1 + tmp3;
             }