Use shared instances

Author: JimBobSquarePants

src/ImageSharp/Formats/Png/PngDecoderCore.cs

@@ -121,6 +121,11 @@ internal sealed class PngDecoderCore : IImageDecoderInternals
     /// </summary>
     private readonly PngCrcChunkHandling pngCrcChunkHandling;
 
+    /// <summary>
+    /// A reusable Crc32 hashing instance.
+    /// </summary>
+    private readonly Crc32 crc32 = new();
+
     /// <summary>
     /// Initializes a new instance of the <see cref="PngDecoderCore"/> class.
     /// </summary>
@@ -1912,11 +1917,11 @@ private void ValidateChunk(in PngChunk chunk, Span<byte> buffer)
             Span<byte> chunkType = stackalloc byte[4];
             BinaryPrimitives.WriteUInt32BigEndian(chunkType, (uint)chunk.Type);
 
-            Crc32 crc32 = new();
-            crc32.Append(chunkType);
-            crc32.Append(chunk.Data.GetSpan());
+            this.crc32.Reset();
+            this.crc32.Append(chunkType);
+            this.crc32.Append(chunk.Data.GetSpan());
 
-            if (crc32.GetCurrentHashAsUInt32() != inputCrc)
+            if (this.crc32.GetCurrentHashAsUInt32() != inputCrc)
             {
                 string chunkTypeName = Encoding.ASCII.GetString(chunkType);
 

src/ImageSharp/Formats/Png/PngEncoderCore.cs

@@ -124,6 +124,11 @@ internal sealed class PngEncoderCore : IImageEncoderInternals, IDisposable
     /// </summary>
     private int derivedTransparencyIndex = -1;
 
+    /// <summary>
+    /// A reusable Crc32 hashing instance.
+    /// </summary>
+    private readonly Crc32 crc32 = new();
+
     /// <summary>
     /// Initializes a new instance of the <see cref="PngEncoderCore" /> class.
     /// </summary>
@@ -1364,17 +1369,17 @@ private void WriteChunk(Stream stream, PngChunkType type, Span<byte> data, int o
 
         stream.Write(buffer);
 
-        Crc32 crc32 = new();
-        crc32.Append(buffer[4..]); // Write the type buffer
+        this.crc32.Reset();
+        this.crc32.Append(buffer[4..]); // Write the type buffer
 
         if (data.Length > 0 && length > 0)
         {
             stream.Write(data, offset, length);
 
-            crc32.Append(data.Slice(offset, length));
+            this.crc32.Append(data.Slice(offset, length));
         }
 
-        BinaryPrimitives.WriteUInt32BigEndian(buffer, crc32.GetCurrentHashAsUInt32());
+        BinaryPrimitives.WriteUInt32BigEndian(buffer, this.crc32.GetCurrentHashAsUInt32());
 
         stream.Write(buffer, 0, 4); // write the crc
     }
@@ -1397,17 +1402,17 @@ private void WriteFrameDataChunk(Stream stream, uint sequenceNumber, Span<byte>
 
         stream.Write(buffer);
 
-        Crc32 crc32 = new();
-        crc32.Append(buffer[4..]); // Write the type buffer
+        this.crc32.Reset();
+        this.crc32.Append(buffer[4..]); // Write the type buffer
 
         if (data.Length > 0 && length > 0)
         {
             stream.Write(data, offset, length);
 
-            crc32.Append(data.Slice(offset, length));
+            this.crc32.Append(data.Slice(offset, length));
         }
 
-        BinaryPrimitives.WriteUInt32BigEndian(buffer, crc32.GetCurrentHashAsUInt32());
+        BinaryPrimitives.WriteUInt32BigEndian(buffer, this.crc32.GetCurrentHashAsUInt32());
 
         stream.Write(buffer, 0, 4); // write the crc
     }

tests/ImageSharp.Benchmarks/Bulk/ToVector4_Rgba32.cs

@@ -11,7 +11,7 @@
 
 namespace SixLabors.ImageSharp.Benchmarks.Bulk;
 
-[Config(typeof(Config.ShortCore31))]
+[Config(typeof(Config.Short))]
 public class ToVector4_Rgba32 : ToVector4<Rgba32>
 {
     [Benchmark]