diff --git a/src/ImageSharp/Formats/Png/Filters/UpFilter.cs b/src/ImageSharp/Formats/Png/Filters/UpFilter.cs index 7e0286991b..2d2a442a19 100644 --- a/src/ImageSharp/Formats/Png/Filters/UpFilter.cs +++ b/src/ImageSharp/Formats/Png/Filters/UpFilter.cs @@ -21,7 +21,7 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters internal static class UpFilter { /// - /// Decodes the scanline + /// Decodes a scanline, which was filtered with the up filter. /// /// The scanline to decode /// The previous scanline. @@ -30,6 +30,55 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters { DebugGuard.MustBeSameSized(scanline, previousScanline, nameof(scanline)); +#if SUPPORTS_RUNTIME_INTRINSICS + if (Sse2.IsSupported) + { + DecodeSse2(scanline, previousScanline); + } + else +#endif + { + DecodeScalar(scanline, previousScanline); + } + } + +#if SUPPORTS_RUNTIME_INTRINSICS + private static void DecodeSse2(Span scanline, Span previousScanline) + { + ref byte scanBaseRef = ref MemoryMarshal.GetReference(scanline); + ref byte prevBaseRef = ref MemoryMarshal.GetReference(previousScanline); + + // Up(x) + Prior(x) + int rb = scanline.Length; + int offset = 1; + const int bytesPerBatch = 16; + while (rb >= bytesPerBatch) + { + ref byte scanRef = ref Unsafe.Add(ref scanBaseRef, offset); + Vector128 current = Unsafe.As>(ref scanRef); + Vector128 up = Unsafe.As>(ref Unsafe.Add(ref prevBaseRef, offset)); + + Vector128 sum = Sse2.Add(up, current); + Unsafe.As>(ref scanRef) = sum; + + offset += bytesPerBatch; + rb -= bytesPerBatch; + } + + // Handle left over. + for (int i = offset; i < scanline.Length; i++) + { + ref byte scan = ref Unsafe.Add(ref scanBaseRef, offset); + byte above = Unsafe.Add(ref prevBaseRef, offset); + scan = (byte)(scan + above); + offset++; + } + } +#endif + + [MethodImpl(MethodImplOptions.AggressiveInlining)] + private static void DecodeScalar(Span scanline, Span previousScanline) + { ref byte scanBaseRef = ref MemoryMarshal.GetReference(scanline); ref byte prevBaseRef = ref MemoryMarshal.GetReference(previousScanline); @@ -43,12 +92,12 @@ namespace SixLabors.ImageSharp.Formats.Png.Filters } /// - /// Encodes the scanline + /// Encodes a scanline with the up filter applied. /// - /// The scanline to encode + /// The scanline to encode. /// The previous scanline. /// The filtered scanline result. - /// The sum of the total variance of the filtered row + /// The sum of the total variance of the filtered row. [MethodImpl(MethodImplOptions.AggressiveInlining)] public static void Encode(ReadOnlySpan scanline, ReadOnlySpan previousScanline, Span result, out int sum) {