Vectorize (AVX2) JPEG Color Converter

src/ImageSharp/Common/Helpers/SimdUtils.cs

@@ -25,6 +25,25 @@ internal static partial class SimdUtils
         public static bool HasVector8 { get; } =
             Vector.IsHardwareAccelerated && Vector<float>.Count == 8 && Vector<int>.Count == 8;
 
+        /// <summary>
+        /// Gets a value indicating whether <see cref="Vector{T}"/> code is being JIT-ed to SSE instructions
+        /// where float and integer registers are of size 128 byte.
+        /// </summary>
+        public static bool HasVector4 { get; } =
+            Vector.IsHardwareAccelerated && Vector<float>.Count == 4;
+
+        public static bool HasAvx2
+        {
+            get
+            {
+#if SUPPORTS_RUNTIME_INTRINSICS
+                return Avx2.IsSupported;
+#else
+                return false;
+#endif
+            }
+        }
+
         /// <summary>
         /// Transform all scalars in 'v' in a way that converting them to <see cref="int"/> would have rounding semantics.
         /// </summary>

src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.Avx2JpegColorConverter.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
+{
+    internal abstract partial class JpegColorConverter
+    {
+        internal abstract class Avx2JpegColorConverter : VectorizedJpegColorConverter
+        {
+            protected Avx2JpegColorConverter(JpegColorSpace colorSpace, int precision)
+                : base(colorSpace, precision, 8)
+            {
+            }
+
+            protected sealed override bool IsAvailable => SimdUtils.HasAvx2;
+        }
+    }
+}

src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.BasicJpegColorConverter.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
+{
+    internal abstract partial class JpegColorConverter
+    {
+        internal abstract class BasicJpegColorConverter : JpegColorConverter
+        {
+            protected BasicJpegColorConverter(JpegColorSpace colorSpace, int precision)
+                : base(colorSpace, precision)
+            {
+            }
+
+            protected override bool IsAvailable => true;
+        }
+    }
+}

src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromCmykAvx2.cs

@@ -0,0 +1,81 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+#if SUPPORTS_RUNTIME_INTRINSICS
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.X86;
+using static SixLabors.ImageSharp.SimdUtils;
+#endif
+
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
+{
+    internal abstract partial class JpegColorConverter
+    {
+        internal sealed class FromCmykAvx2 : Avx2JpegColorConverter
+        {
+            public FromCmykAvx2(int precision)
+                : base(JpegColorSpace.Cmyk, precision)
+            {
+            }
+
+            protected override void ConvertCoreVectorized(in ComponentValues values, Span<Vector4> result)
+            {
+#if SUPPORTS_RUNTIME_INTRINSICS
+                ref Vector256<float> cBase =
+                                    ref Unsafe.As<float, Vector256<float>>(ref MemoryMarshal.GetReference(values.Component0));
+                ref Vector256<float> mBase =
+                                    ref Unsafe.As<float, Vector256<float>>(ref MemoryMarshal.GetReference(values.Component1));
+                ref Vector256<float> yBase =
+                                    ref Unsafe.As<float, Vector256<float>>(ref MemoryMarshal.GetReference(values.Component2));
+                ref Vector256<float> kBase =
+                                    ref Unsafe.As<float, Vector256<float>>(ref MemoryMarshal.GetReference(values.Component3));
+
+                ref Vector256<float> resultBase =
+                    ref Unsafe.As<Vector4, Vector256<float>>(ref MemoryMarshal.GetReference(result));
+
+                // Used for the color conversion
+                var scale = Vector256.Create(1 / this.MaximumValue);
+                var one = Vector256.Create(1F);
+
+                // Used for packing
+                ref byte control = ref MemoryMarshal.GetReference(HwIntrinsics.PermuteMaskEvenOdd8x32);
+                Vector256<int> vcontrol = Unsafe.As<byte, Vector256<int>>(ref control);
+
+                int n = result.Length / 8;
+                for (int i = 0; i < n; i++)
+                {
+                    Vector256<float> k = Avx2.PermuteVar8x32(Unsafe.Add(ref kBase, i), vcontrol);
+                    Vector256<float> c = Avx2.PermuteVar8x32(Unsafe.Add(ref cBase, i), vcontrol);
+                    Vector256<float> m = Avx2.PermuteVar8x32(Unsafe.Add(ref mBase, i), vcontrol);
+                    Vector256<float> y = Avx2.PermuteVar8x32(Unsafe.Add(ref yBase, i), vcontrol);
+
+                    k = Avx.Multiply(k, scale);
+
+                    c = Avx.Multiply(Avx.Multiply(c, k), scale);
+                    m = Avx.Multiply(Avx.Multiply(m, k), scale);
+                    y = Avx.Multiply(Avx.Multiply(y, k), scale);
+
+                    Vector256<float> cmLo = Avx.UnpackLow(c, m);
+                    Vector256<float> yoLo = Avx.UnpackLow(y, one);
+                    Vector256<float> cmHi = Avx.UnpackHigh(c, m);
+                    Vector256<float> yoHi = Avx.UnpackHigh(y, one);
+
+                    ref Vector256<float> destination = ref Unsafe.Add(ref resultBase, i * 4);
+
+                    destination = Avx.Shuffle(cmLo, yoLo, 0b01_00_01_00);
+                    Unsafe.Add(ref destination, 1) = Avx.Shuffle(cmLo, yoLo, 0b11_10_11_10);
+                    Unsafe.Add(ref destination, 2) = Avx.Shuffle(cmHi, yoHi, 0b01_00_01_00);
+                    Unsafe.Add(ref destination, 3) = Avx.Shuffle(cmHi, yoHi, 0b11_10_11_10);
+                }
+#endif
+            }
+
+            protected override void ConvertCore(in ComponentValues values, Span<Vector4> result) =>
+                FromCmykBasic.ConvertCore(values, result, this.MaximumValue);
+        }
+    }
+}

src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromCmyk.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromCmykBasic.cs

@@ -8,32 +8,36 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
 {
     internal abstract partial class JpegColorConverter
     {
-        internal sealed class FromCmyk : JpegColorConverter
+        internal sealed class FromCmykBasic : BasicJpegColorConverter
         {
-            public FromCmyk(int precision)
+            public FromCmykBasic(int precision)
                 : base(JpegColorSpace.Cmyk, precision)
             {
             }
 
             public override void ConvertToRgba(in ComponentValues values, Span<Vector4> result)
             {
-                // TODO: We can optimize a lot here with Vector<float> and SRCS.Unsafe()!
+                ConvertCore(values, result, this.MaximumValue);
+            }
+
+            internal static void ConvertCore(in ComponentValues values, Span<Vector4> result, float maxValue)
+            {
                 ReadOnlySpan<float> cVals = values.Component0;
                 ReadOnlySpan<float> mVals = values.Component1;
                 ReadOnlySpan<float> yVals = values.Component2;
                 ReadOnlySpan<float> kVals = values.Component3;
 
                 var v = new Vector4(0, 0, 0, 1F);
 
-                var maximum = 1 / this.MaximumValue;
+                var maximum = 1 / maxValue;
                 var scale = new Vector4(maximum, maximum, maximum, 1F);
 
                 for (int i = 0; i < result.Length; i++)
                 {
                     float c = cVals[i];
                     float m = mVals[i];
                     float y = yVals[i];
-                    float k = kVals[i] / this.MaximumValue;
+                    float k = kVals[i] / maxValue;
 
                     v.X = c * k;
                     v.Y = m * k;
@@ -47,4 +51,4 @@ public override void ConvertToRgba(in ComponentValues values, Span<Vector4> resu
             }
         }
     }
-}
+}

src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromCmykVector8.cs

@@ -0,0 +1,71 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+using SixLabors.ImageSharp.Tuples;
+
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
+{
+    internal abstract partial class JpegColorConverter
+    {
+        internal sealed class FromCmykVector8 : Vector8JpegColorConverter
+        {
+            public FromCmykVector8(int precision)
+                : base(JpegColorSpace.Cmyk, precision)
+            {
+            }
+
+            protected override void ConvertCoreVectorized(in ComponentValues values, Span<Vector4> result)
+            {
+                ref Vector<float> cBase =
+                                    ref Unsafe.As<float, Vector<float>>(ref MemoryMarshal.GetReference(values.Component0));
+                ref Vector<float> mBase =
+                                    ref Unsafe.As<float, Vector<float>>(ref MemoryMarshal.GetReference(values.Component1));
+                ref Vector<float> yBase =
+                                    ref Unsafe.As<float, Vector<float>>(ref MemoryMarshal.GetReference(values.Component2));
+                ref Vector<float> kBase =
+                                    ref Unsafe.As<float, Vector<float>>(ref MemoryMarshal.GetReference(values.Component3));
+
+                ref Vector4Octet resultBase =
+                    ref Unsafe.As<Vector4, Vector4Octet>(ref MemoryMarshal.GetReference(result));
+
+                Vector4Pair cc = default;
+                Vector4Pair mm = default;
+                Vector4Pair yy = default;
+                ref Vector<float> ccRefAsVector = ref Unsafe.As<Vector4Pair, Vector<float>>(ref cc);
+                ref Vector<float> mmRefAsVector = ref Unsafe.As<Vector4Pair, Vector<float>>(ref mm);
+                ref Vector<float> yyRefAsVector = ref Unsafe.As<Vector4Pair, Vector<float>>(ref yy);
+
+                var scale = new Vector<float>(1 / this.MaximumValue);
+
+                // Walking 8 elements at one step:
+                int n = result.Length / 8;
+                for (int i = 0; i < n; i++)
+                {
+                    Vector<float> c = Unsafe.Add(ref cBase, i);
+                    Vector<float> m = Unsafe.Add(ref mBase, i);
+                    Vector<float> y = Unsafe.Add(ref yBase, i);
+                    Vector<float> k = Unsafe.Add(ref kBase, i) * scale;
+
+                    c = (c * k) * scale;
+                    m = (m * k) * scale;
+                    y = (y * k) * scale;
+
+                    ccRefAsVector = c;
+                    mmRefAsVector = m;
+                    yyRefAsVector = y;
+
+                    // Collect (c0,c1...c8) (m0,m1...m8) (y0,y1...y8) vector values in the expected (r0,g0,g1,1), (r1,g1,g2,1) ... order:
+                    ref Vector4Octet destination = ref Unsafe.Add(ref resultBase, i);
+                    destination.Pack(ref cc, ref mm, ref yy);
+                }
+            }
+
+            protected override void ConvertCore(in ComponentValues values, Span<Vector4> result) =>
+                FromCmykBasic.ConvertCore(values, result, this.MaximumValue);
+        }
+    }
+}

src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromGrayScaleAvx2.cs

@@ -0,0 +1,63 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+using System.Numerics;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+#if SUPPORTS_RUNTIME_INTRINSICS
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.X86;
+using static SixLabors.ImageSharp.SimdUtils;
+#endif
+
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
+{
+    internal abstract partial class JpegColorConverter
+    {
+        internal sealed class FromGrayscaleAvx2 : Avx2JpegColorConverter
+        {
+            public FromGrayscaleAvx2(int precision)
+                : base(JpegColorSpace.Grayscale, precision)
+            {
+            }
+
+            protected override void ConvertCoreVectorized(in ComponentValues values, Span<Vector4> result)
+            {
+#if SUPPORTS_RUNTIME_INTRINSICS
+                ref Vector256<float> gBase =
+                    ref Unsafe.As<float, Vector256<float>>(ref MemoryMarshal.GetReference(values.Component0));
+
+                ref Vector256<float> resultBase =
+                    ref Unsafe.As<Vector4, Vector256<float>>(ref MemoryMarshal.GetReference(result));
+
+                // Used for the color conversion
+                var scale = Vector256.Create(1 / this.MaximumValue);
+                var one = Vector256.Create(1F);
+
+                // Used for packing
+                ref byte control = ref MemoryMarshal.GetReference(HwIntrinsics.PermuteMaskEvenOdd8x32);
+                Vector256<int> vcontrol = Unsafe.As<byte, Vector256<int>>(ref control);
+
+                int n = result.Length / 8;
+                for (int i = 0; i < n; i++)
+                {
+                    Vector256<float> g = Avx2.PermuteVar8x32(Unsafe.Add(ref gBase, i), vcontrol);
+
+                    g = Avx.Multiply(g, scale);
+
+                    ref Vector256<float> destination = ref Unsafe.Add(ref resultBase, i * 4);
+
+                    destination = Avx.Blend(Avx.Permute(g, 0b00_00_00_00), one, 0b1000_1000);
+                    Unsafe.Add(ref destination, 1) = Avx.Blend(Avx.Permute(g, 0b01_01_01_01), one, 0b1000_1000);
+                    Unsafe.Add(ref destination, 2) = Avx.Blend(Avx.Permute(g, 0b10_10_10_10), one, 0b1000_1000);
+                    Unsafe.Add(ref destination, 3) = Avx.Blend(Avx.Permute(g, 0b11_11_11_11), one, 0b1000_1000);
+                }
+#endif
+            }
+
+            protected override void ConvertCore(in ComponentValues values, Span<Vector4> result) =>
+                FromGrayscaleBasic.ConvertCore(values, result, this.MaximumValue);
+        }
+    }
+}

src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromGrayScale.cs → src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromGrayScaleBasic.cs

@@ -10,16 +10,21 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder.ColorConverters
 {
     internal abstract partial class JpegColorConverter
     {
-        internal sealed class FromGrayscale : JpegColorConverter
+        internal sealed class FromGrayscaleBasic : BasicJpegColorConverter
         {
-            public FromGrayscale(int precision)
+            public FromGrayscaleBasic(int precision)
                 : base(JpegColorSpace.Grayscale, precision)
             {
             }
 
             public override void ConvertToRgba(in ComponentValues values, Span<Vector4> result)
             {
-                var maximum = 1 / this.MaximumValue;
+                ConvertCore(values, result, this.MaximumValue);
+            }
+
+            internal static void ConvertCore(in ComponentValues values, Span<Vector4> result, float maxValue)
+            {
+                var maximum = 1 / maxValue;
                 var scale = new Vector4(maximum, maximum, maximum, 1F);
 
                 ref float sBase = ref MemoryMarshal.GetReference(values.Component0);
@@ -35,4 +40,4 @@ public override void ConvertToRgba(in ComponentValues values, Span<Vector4> resu
             }
         }
     }
-}
+}