entry API & tests

src/ImageSharp/Common/Helpers/SimdUtils.cs

@@ -6,6 +6,7 @@ using System.Diagnostics;
 using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+using SixLabors.ImageSharp.PixelFormats;
 #if SUPPORTS_RUNTIME_INTRINSICS
 using System.Runtime.Intrinsics;
 using System.Runtime.Intrinsics.X86;
@@ -147,6 +148,26 @@ namespace SixLabors.ImageSharp
             }
         }
 
+        [MethodImpl(InliningOptions.ShortMethod)]
+        internal static void PackFromRgbPlanes(
+            Configuration configuration,
+            ReadOnlySpan<byte> redChannel,
+            ReadOnlySpan<byte> greenChannel,
+            ReadOnlySpan<byte> blueChannel,
+            Span<Rgb24> destination)
+        {
+        }
+
+        [MethodImpl(InliningOptions.ShortMethod)]
+        internal static void PackFromRgbPlanes(
+            Configuration configuration,
+            ReadOnlySpan<byte> redChannel,
+            ReadOnlySpan<byte> greenChannel,
+            ReadOnlySpan<byte> blueChannel,
+            Span<Rgba32> destination)
+        {
+        }
+
         [MethodImpl(InliningOptions.ColdPath)]
         private static void ConvertByteToNormalizedFloatRemainder(ReadOnlySpan<byte> source, Span<float> dest)
         {

src/ImageSharp/PixelFormats/PixelOperations{TPixel}.cs

@@ -159,5 +159,31 @@ namespace SixLabors.ImageSharp.PixelFormats
 
             PixelOperations<TDestinationPixel>.Instance.From(configuration, sourcePixels, destinationPixels);
         }
+
+        /// <summary>
+        /// Bulk operation that converts 3 seperate RGB channels to <paramref name="destination"/>
+        /// </summary>
+        /// <param name="configuration">A <see cref="Configuration"/> to configure internal operations.</param>
+        /// <param name="redChannel">A <see cref="ReadOnlySpan{T}"/> to the red values.</param>
+        /// <param name="greenChannel">A <see cref="ReadOnlySpan{T}"/> to the green values.</param>
+        /// <param name="blueChannel">A <see cref="ReadOnlySpan{T}"/> to the blue values.</param>
+        /// <param name="destination">A <see cref="Span{T}"/> to the destination pixels.</param>
+        public virtual void PackFromRgbPlanes(
+            Configuration configuration,
+            ReadOnlySpan<byte> redChannel,
+            ReadOnlySpan<byte> greenChannel,
+            ReadOnlySpan<byte> blueChannel,
+            Span<TPixel> destination)
+        {
+            Guard.NotNull(configuration, nameof(configuration));
+            Guard.DestinationShouldNotBeTooShort(redChannel, destination, nameof(destination));
+
+            for (int i = 0; i < destination.Length; i++)
+            {
+                var rgb24 = new Rgb24(redChannel[i], greenChannel[i], blueChannel[i]);
+
+                destination[i].FromRgb24(rgb24);
+            }
+        }
     }
 }

tests/ImageSharp.Tests/Common/SimdUtilsTests.cs

@@ -7,6 +7,7 @@ using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.Common.Tuples;
+using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Tests.TestUtilities;
 using Xunit;
 using Xunit.Abstractions;
@@ -336,90 +337,64 @@ namespace SixLabors.ImageSharp.Tests.Common
             }
         }
 
-        private static void TestImpl_BulkConvertNormalizedFloatToByteClampOverflows(
-            int count,
-            Action<Memory<float>,
-            Memory<byte>> convert,
-            int seed = -1)
+        [Theory]
+        [MemberData(nameof(ArbitraryArraySizes))]
+        public void PackFromRgbPlanes_Rgb24(int count)
         {
-            seed = seed > 0 ? seed : count;
-            float[] source = new Random(seed).GenerateRandomFloatArray(count, -0.2f, 1.2f);
-            byte[] expected = source.Select(NormalizedFloatToByte).ToArray();
-            var actual = new byte[count];
-
-            convert(source, actual);
-
-            Assert.Equal(expected, actual);
+            TestPackFromRgbPlanes<Rgb24>(
+                count,
+                (r, g, b, actual) =>
+                    SimdUtils.PackFromRgbPlanes(Configuration.Default, r, g, b, actual));
         }
 
-        private static byte NormalizedFloatToByte(float f) => (byte)Math.Min(255f, Math.Max(0f, (f * 255f) + 0.5f));
-
         [Theory]
-        [InlineData(0)]
-        [InlineData(7)]
-        [InlineData(42)]
-        [InlineData(255)]
-        [InlineData(256)]
-        [InlineData(257)]
-        private void MagicConvertToByte(float value)
+        [MemberData(nameof(ArbitraryArraySizes))]
+        public void PackFromRgbPlanes_Rgba32(int count)
         {
-            byte actual = MagicConvert(value / 256f);
-            var expected = (byte)value;
-
-            Assert.Equal(expected, actual);
+            TestPackFromRgbPlanes<Rgba32>(
+                count,
+                (r, g, b, actual) =>
+                    SimdUtils.PackFromRgbPlanes(Configuration.Default, r, g, b, actual));
         }
 
-        [Fact]
-        private void BulkConvertNormalizedFloatToByte_Step()
+        internal static void TestPackFromRgbPlanes<TPixel>(int count, Action<byte[], byte[], byte[], TPixel[]> packMethod)
+            where TPixel : unmanaged, IPixel<TPixel>
         {
-            if (this.SkipOnNonAvx2())
+            Random rnd = new Random(42);
+            byte[] r = rnd.GenerateRandomByteArray(count);
+            byte[] g = rnd.GenerateRandomByteArray(count);
+            byte[] b = rnd.GenerateRandomByteArray(count);
+
+            TPixel[] expected = new TPixel[count];
+            for (int i = 0; i < count; i++)
             {
-                return;
+                expected[i].FromRgb24(new Rgb24(r[i], g[i], b[i]));
             }
 
-            float[] source = { 0, 7, 42, 255, 0.5f, 1.1f, 2.6f, 16f };
-
-            byte[] expected = source.Select(f => (byte)Math.Round(f)).ToArray();
+            TPixel[] actual = new TPixel[count];
+            packMethod(r, g, b, actual);
 
-            source = source.Select(f => f / 255f).ToArray();
-
-            Span<byte> dest = stackalloc byte[8];
-
-            this.MagicConvert(source, dest);
-
-            Assert.True(dest.SequenceEqual(expected));
-        }
-
-        private static byte MagicConvert(float x)
-        {
-            float f = 32768.0f + x;
-            uint i = Unsafe.As<float, uint>(ref f);
-            return (byte)i;
+            Assert.Equal(expected, actual);
         }
 
-        private void MagicConvert(Span<float> source, Span<byte> dest)
+        private static void TestImpl_BulkConvertNormalizedFloatToByteClampOverflows(
+            int count,
+            Action<Memory<float>,
+            Memory<byte>> convert,
+            int seed = -1)
         {
-            var magick = new Vector<float>(32768.0f);
-
-            var scale = new Vector<float>(255f) / new Vector<float>(256f);
-
-            Vector<float> x = MemoryMarshal.Cast<float, Vector<float>>(source)[0];
-
-            x = (x * scale) + magick;
-
-            Tuple8.OfUInt32 ii = default;
-
-            ref Vector<float> iiRef = ref Unsafe.As<Tuple8.OfUInt32, Vector<float>>(ref ii);
-
-            iiRef = x;
+            seed = seed > 0 ? seed : count;
+            float[] source = new Random(seed).GenerateRandomFloatArray(count, -0.2f, 1.2f);
+            byte[] expected = source.Select(NormalizedFloatToByte).ToArray();
+            var actual = new byte[count];
 
-            ref Tuple8.OfByte d = ref MemoryMarshal.Cast<byte, Tuple8.OfByte>(dest)[0];
-            d.LoadFrom(ref ii);
+            convert(source, actual);
 
-            this.Output.WriteLine(ii.ToString());
-            this.Output.WriteLine(d.ToString());
+            Assert.Equal(expected, actual);
         }
 
+        private static byte NormalizedFloatToByte(float f) => (byte)Math.Min(255f, Math.Max(0f, (f * 255f) + 0.5f));
+
         private static void AssertEvenRoundIsCorrect(Vector<float> r, Vector<float> v)
         {
             for (int i = 0; i < Vector<float>.Count; i++)

tests/ImageSharp.Tests/PixelFormats/PixelOperations/PixelOperationsTests.cs

@@ -10,6 +10,7 @@ using System.Runtime.InteropServices;
 using SixLabors.ImageSharp.ColorSpaces.Companding;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
+using SixLabors.ImageSharp.Tests.Common;
 using SixLabors.ImageSharp.Tests.TestUtilities;
 using Xunit;
 using Xunit.Abstractions;
@@ -1002,6 +1003,19 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats.PixelOperations
                 (s, d) => this.Operations.ToRgba64Bytes(this.Configuration, s, d.GetSpan(), count));
         }
 
+        [Theory]
+        [MemberData(nameof(ArraySizesData))]
+        public void PackFromRgbPlanes(int count)
+        {
+            SimdUtilsTests.TestPackFromRgbPlanes<TPixel>(
+                count,
+                (
+                    r,
+                    g,
+                    b,
+                    actual) => PixelOperations<TPixel>.Instance.PackFromRgbPlanes(this.Configuration, r, g, b, actual));
+        }
+
         public delegate void RefAction<T1>(ref T1 arg1);
 
         internal static Vector4[] CreateExpectedVector4Data(TPixel[] source, RefAction<Vector4> vectorModifier = null)
@@ -1102,10 +1116,10 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats.PixelOperations
             return result;
         }
 
-        internal static byte[] CreateByteTestData(int length)
+        internal static byte[] CreateByteTestData(int length, int seed = 42)
         {
             byte[] result = new byte[length];
-            var rnd = new Random(42); // Deterministic random values
+            var rnd = new Random(seed); // Deterministic random values
 
             for (int i = 0; i < result.Length; i++)
             {