Expand Clamp benchmark [skip ci]

tests/ImageSharp.Benchmarks/General/Clamp.cs

@@ -6,6 +6,7 @@
 namespace ImageSharp.Benchmarks.General
 {
     using System;
+    using System.Runtime.CompilerServices;
 
     using BenchmarkDotNet.Attributes;
 
@@ -17,24 +18,24 @@ namespace ImageSharp.Benchmarks.General
         [Benchmark(Baseline = true, Description = "Maths Clamp")]
         public byte ClampMaths()
         {
-            int value = this.Value;
-            return (byte)Math.Min(Math.Max(0, value), 255);
+           int value = this.Value;
+           return (byte)Math.Min(Math.Max(byte.MinValue, value), byte.MaxValue);
         }
 
         [Benchmark(Description = "No Maths Clamp")]
         public byte ClampNoMaths()
         {
-            int value = this.Value;
-            value = value >= 255 ? 255 : value;
-            return (byte)(value <= 0 ? 0 : value);
+           int value = this.Value;
+           value = value >= byte.MaxValue ? byte.MaxValue : value;
+           return (byte)(value <= byte.MinValue ? byte.MinValue : value);
         }
 
         [Benchmark(Description = "No Maths No Equals Clamp")]
         public byte ClampNoMathsNoEquals()
         {
-            int value = this.Value;
-            value = value > 255 ? 255 : value;
-            return (byte)(value < 0 ? 0 : value);
+           int value = this.Value;
+           value = value > byte.MaxValue ? byte.MaxValue : value;
+           return (byte)(value < byte.MinValue ? byte.MinValue : value);
         }
 
         [Benchmark(Description = "No Maths Clamp No Ternary")]
@@ -42,14 +43,14 @@ namespace ImageSharp.Benchmarks.General
         {
             int value = this.Value;
 
-            if (value >= 255)
+            if (value >= byte.MaxValue)
             {
-                return 255;
+                return byte.MaxValue;
             }
 
-            if (value <= 0)
+            if (value <= byte.MinValue)
             {
-                return 0;
+                return byte.MinValue;
             }
 
             return (byte)value;
@@ -58,19 +59,37 @@ namespace ImageSharp.Benchmarks.General
         [Benchmark(Description = "No Maths No Equals Clamp No Ternary")]
         public byte ClampNoMathsEqualsNoTernary()
         {
-            int value = this.Value;
+           int value = this.Value;
 
-            if (value > 255)
-            {
-                return 255;
-            }
+           if (value > byte.MaxValue)
+           {
+               return byte.MaxValue;
+           }
 
-            if (value < 0)
-            {
-                return 0;
-            }
+           if (value < byte.MinValue)
+           {
+               return byte.MinValue;
+           }
 
-            return (byte)value;
+           return (byte)value;
+        }
+
+        [Benchmark(Description = "Clamp using Bitwise Abs")]
+        public byte ClampBitwise()
+        {
+            int x = this.Value;
+            int absmax = byte.MaxValue - x;
+            x = (x + byte.MaxValue - AbsBitwiseVer(ref absmax)) >> 1;
+            x = (x + byte.MinValue + AbsBitwiseVer(ref x)) >> 1;
+
+            return (byte)x;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static int AbsBitwiseVer(ref int x)
+        {
+            int y = x >> 31;
+            return (x ^ y) - y;
         }
     }
 }