From f5e73368a104211d6216c95047d48d8c2ffc337f Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Thu, 14 Jul 2016 14:18:22 +1000
Subject: [PATCH] Faster clamp

30% performance increase removing ternary operator.


Former-commit-id: 9664ddb7da1c63be4034d0466ac10560db42edf0
Former-commit-id: 019ec4638e02acdf8bafc1f251859a25f75f07d2
Former-commit-id: 9b608a6ba964226e0f45d023d466f207aa24c796
---
 src/ImageProcessorCore/PackedVector/Bgra32.cs | 24 +++++++++++++++----
 .../Color/Clamp.cs                            | 17 +++++++++++++
 .../Samplers/Resize.cs                        |  2 +-
 3 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/src/ImageProcessorCore/PackedVector/Bgra32.cs b/src/ImageProcessorCore/PackedVector/Bgra32.cs
index eed4d5c02f..3372cb2833 100644
--- a/src/ImageProcessorCore/PackedVector/Bgra32.cs
+++ b/src/ImageProcessorCore/PackedVector/Bgra32.cs
@@ -270,8 +270,16 @@ namespace ImageProcessorCore
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static byte Clamp(float value)
         {
-            value = (value > 255) ? 255 : value;
-            value = (value < 0) ? 0 : value;
+            if (value > 255)
+            {
+                return 255;
+            }
+
+            if (value < 0)
+            {
+                return 0;
+            }
+
             return (byte)value;
         }
 
@@ -285,8 +293,16 @@ namespace ImageProcessorCore
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static byte Clamp(double value)
         {
-            value = (value > 255) ? 255 : value;
-            value = (value < 0) ? 0 : value;
+            if (value > 255)
+            {
+                return 255;
+            }
+
+            if (value < 0)
+            {
+                return 0;
+            }
+
             return (byte)value;
         }
 
diff --git a/tests/ImageProcessorCore.Benchmarks/Color/Clamp.cs b/tests/ImageProcessorCore.Benchmarks/Color/Clamp.cs
index 93b6cd94e6..7af7010ab8 100644
--- a/tests/ImageProcessorCore.Benchmarks/Color/Clamp.cs
+++ b/tests/ImageProcessorCore.Benchmarks/Color/Clamp.cs
@@ -22,5 +22,22 @@ namespace ImageProcessorCore.Benchmarks.Color
             return (byte)value;
         }
 
+        [Benchmark(Description = "No Maths Clamp No Ternary")]
+        public byte ClampNoMathsNoTernary()
+        {
+            double value = 256;
+
+            if(value > 255)
+            {
+                return 255;
+            }
+
+            if (value < 0)
+            {
+                return 0;
+            }
+
+            return (byte)value;
+        }
     }
 }
diff --git a/tests/ImageProcessorCore.Benchmarks/Samplers/Resize.cs b/tests/ImageProcessorCore.Benchmarks/Samplers/Resize.cs
index 65ed841f00..e5eb412f29 100644
--- a/tests/ImageProcessorCore.Benchmarks/Samplers/Resize.cs
+++ b/tests/ImageProcessorCore.Benchmarks/Samplers/Resize.cs
@@ -21,7 +21,7 @@
                         graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
                         graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;
                         graphics.CompositingQuality = CompositingQuality.HighQuality;
-                        graphics.DrawImage(source, 0, 0, 100, 100);
+                        graphics.DrawImage(source, 0, 0, 400, 400);
                     }
 
                     return destination.Size;