From ea49ba226ac66366bb14bacd6e759ce511c10b51 Mon Sep 17 00:00:00 2001
From: James Jackson-South <james_south@hotmail.com>
Date: Sat, 9 Dec 2023 19:58:02 +1000
Subject: [PATCH] Use shared instances

---
 src/ImageSharp/Formats/Png/PngDecoderCore.cs  | 13 ++++++++----
 src/ImageSharp/Formats/Png/PngEncoderCore.cs  | 21 ++++++++++++-------
 .../Bulk/ToVector4_Rgba32.cs                  |  2 +-
 3 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/src/ImageSharp/Formats/Png/PngDecoderCore.cs b/src/ImageSharp/Formats/Png/PngDecoderCore.cs
index 3d0ba6f97..3eabbdef0 100644
--- a/src/ImageSharp/Formats/Png/PngDecoderCore.cs
+++ b/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 @@ internal sealed class PngDecoderCore : IImageDecoderInternals
             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);
 
diff --git a/src/ImageSharp/Formats/Png/PngEncoderCore.cs b/src/ImageSharp/Formats/Png/PngEncoderCore.cs
index 751df49f1..e348d7467 100644
--- a/src/ImageSharp/Formats/Png/PngEncoderCore.cs
+++ b/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 @@ internal sealed class PngEncoderCore : IImageEncoderInternals, IDisposable
 
         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 @@ internal sealed class PngEncoderCore : IImageEncoderInternals, IDisposable
 
         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
     }
diff --git a/tests/ImageSharp.Benchmarks/Bulk/ToVector4_Rgba32.cs b/tests/ImageSharp.Benchmarks/Bulk/ToVector4_Rgba32.cs
index 9abf0ed22..1ceae8414 100644
--- a/tests/ImageSharp.Benchmarks/Bulk/ToVector4_Rgba32.cs
+++ b/tests/ImageSharp.Benchmarks/Bulk/ToVector4_Rgba32.cs
@@ -11,7 +11,7 @@ using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Benchmarks.Bulk;
 
-[Config(typeof(Config.ShortCore31))]
+[Config(typeof(Config.Short))]
 public class ToVector4_Rgba32 : ToVector4<Rgba32>
 {
     [Benchmark]