Merge pull request #2618 from SixLabors/js/fix-sse3-paeth

Fix Paeth Filter decode on platforms that do not support Ssse3

Author: JimBobSquarePants

src/ImageSharp/Formats/Png/Filters/PaethFilter.cs

@@ -35,9 +35,9 @@ public static void Decode(Span<byte> scanline, Span<byte> previousScanline, int
         // row:  a d
         // The Paeth function predicts d to be whichever of a, b, or c is nearest to
         // p = a + b - c.
-        if (Sse2.IsSupported && bytesPerPixel is 4)
+        if (Ssse3.IsSupported && bytesPerPixel is 4)
         {
-            DecodeSse3(scanline, previousScanline);
+            DecodeSsse3(scanline, previousScanline);
         }
         else if (AdvSimd.Arm64.IsSupported && bytesPerPixel is 4)
         {
@@ -50,7 +50,7 @@ public static void Decode(Span<byte> scanline, Span<byte> previousScanline, int
     }
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    private static void DecodeSse3(Span<byte> scanline, Span<byte> previousScanline)
+    private static void DecodeSsse3(Span<byte> scanline, Span<byte> previousScanline)
     {
         ref byte scanBaseRef = ref MemoryMarshal.GetReference(scanline);
         ref byte prevBaseRef = ref MemoryMarshal.GetReference(previousScanline);

tests/ImageSharp.Tests/Formats/Png/PngDecoderFilterTests.cs

@@ -170,6 +170,9 @@ private static void RunPaethFilterTest()
     [Fact]
     public void PaethFilter_WithHardwareIntrinsics_Works() => FeatureTestRunner.RunWithHwIntrinsicsFeature(RunPaethFilterTest, HwIntrinsics.AllowAll);
 
+    [Fact]
+    public void PaethFilter_WithoutSsse3_Works() => FeatureTestRunner.RunWithHwIntrinsicsFeature(RunPaethFilterTest, HwIntrinsics.DisableSSSE3);
+
     [Fact]
     public void PaethFilter_WithoutHardwareIntrinsics_Works() => FeatureTestRunner.RunWithHwIntrinsicsFeature(RunPaethFilterTest, HwIntrinsics.DisableHWIntrinsic);
 }