From 26d61124b590a64bb85fcebd569cf8bc26e0cd26 Mon Sep 17 00:00:00 2001
From: Ynse Hoornenborg <github@ynse.nl>
Date: Mon, 29 Mar 2021 22:13:53 +0200
Subject: [PATCH] LuminanceForwardConverter handles the entire conversion
 itself

---
 .../Jpeg/Components/Encoder/L8ToYConverter.cs | 49 -------------------
 .../LuminanceForwardConverter{TPixel}.cs      | 14 +++---
 2 files changed, 7 insertions(+), 56 deletions(-)
 delete mode 100644 src/ImageSharp/Formats/Jpeg/Components/Encoder/L8ToYConverter.cs

diff --git a/src/ImageSharp/Formats/Jpeg/Components/Encoder/L8ToYConverter.cs b/src/ImageSharp/Formats/Jpeg/Components/Encoder/L8ToYConverter.cs
deleted file mode 100644
index 6d787c58f..000000000
--- a/src/ImageSharp/Formats/Jpeg/Components/Encoder/L8ToYConverter.cs
+++ /dev/null
@@ -1,49 +0,0 @@
-// Copyright (c) Six Labors.
-// Licensed under the Apache License, Version 2.0.
-
-using System;
-using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.PixelFormats;
-
-namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
-{
-    /// <summary>
-    /// Provides 8-bit lookup tables for converting from L8 to Y colorspace.
-    /// </summary>
-    internal unsafe struct L8ToYConverter
-    {
-        /// <summary>
-        /// Initializes
-        /// </summary>
-        /// <returns>The initialized <see cref="L8ToYConverter"/></returns>
-        public static L8ToYConverter Create()
-        {
-            L8ToYConverter converter = default;
-            return converter;
-        }
-
-        /// <summary>
-        /// Optimized method to allocates the correct y, cb, and cr values to the DCT blocks from the given r, g, b values.
-        /// </summary>
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        private void ConvertPixelInto(
-            int l,
-            ref Block8x8F yResult,
-            int i) => yResult[i] = l;
-
-        public void Convert(Span<L8> l8Span, ref Block8x8F yBlock)
-        {
-            ref L8 l8Start = ref l8Span[0];
-
-            for (int i = 0; i < 64; i++)
-            {
-                ref L8 c = ref Unsafe.Add(ref l8Start, i);
-
-                this.ConvertPixelInto(
-                    c.PackedValue,
-                    ref yBlock,
-                    i);
-            }
-        }
-    }
-}
diff --git a/src/ImageSharp/Formats/Jpeg/Components/Encoder/LuminanceForwardConverter{TPixel}.cs b/src/ImageSharp/Formats/Jpeg/Components/Encoder/LuminanceForwardConverter{TPixel}.cs
index 0b6cde826..cc81130dd 100644
--- a/src/ImageSharp/Formats/Jpeg/Components/Encoder/LuminanceForwardConverter{TPixel}.cs
+++ b/src/ImageSharp/Formats/Jpeg/Components/Encoder/LuminanceForwardConverter{TPixel}.cs
@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Advanced;
 using SixLabors.ImageSharp.PixelFormats;
 
@@ -19,11 +20,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
         /// </summary>
         public Block8x8F Y;
 
-        /// <summary>
-        /// The converter
-        /// </summary>
-        private L8ToYConverter converter;
-
         /// <summary>
         /// Temporal 8x8 block to hold TPixel data
         /// </summary>
@@ -37,7 +33,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
         public static LuminanceForwardConverter<TPixel> Create()
         {
             var result = default(LuminanceForwardConverter<TPixel>);
-            result.converter = L8ToYConverter.Create();
             return result;
         }
 
@@ -52,8 +47,13 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Encoder
             PixelOperations<TPixel>.Instance.ToL8(frame.GetConfiguration(), this.pixelBlock.AsSpanUnsafe(), l8Span);
 
             ref Block8x8F yBlock = ref this.Y;
+            ref L8 l8Start = ref l8Span[0];
 
-            this.converter.Convert(l8Span, ref yBlock);
+            for (int i = 0; i < 64; i++)
+            {
+                ref L8 c = ref Unsafe.Add(ref l8Start, i);
+                yBlock[i] = c.PackedValue;
+            }
         }
     }
 }