App/Controllers/ImageController.cs

@@ -6,7 +6,11 @@ namespace StitchATon2.App.Controllers;
 
 public static class ImageController
 {
-    public static async Task GenerateImage(HttpResponse response, GenerateImageDto dto, TileManager tileManager)
+    public static async Task GenerateImage(
+        HttpResponse response,
+        GenerateImageDto dto,
+        TileManager tileManager,
+        CancellationToken cancellationToken)
     {
         if (dto.GetErrors() is { Count: > 0 } errors)
         {
@@ -14,7 +18,7 @@ public static class ImageController
             response.ContentType = "text/json";
             var errorBody = JsonSerializer.Serialize(errors, AppJsonSerializerContext.Default.DictionaryStringListString);
             response.ContentLength = errorBody.Length;
-            await response.WriteAsync(errorBody);
+            await response.WriteAsync(errorBody, cancellationToken: cancellationToken);
             await response.CompleteAsync();
             return;
         }
@@ -22,14 +26,19 @@ public static class ImageController
         response.StatusCode = 200;
         response.ContentType = "image/png";
         
+        Console.WriteLine($"Generate image for {dto}");
+
         await tileManager
             .CreateSection(dto)
-            .WriteToStream(response.Body, dto.OutputScale);
+            .WriteToPipe(response.BodyWriter, dto.OutputScale, cancellationToken);
         
         await response.CompleteAsync();
     }
     
-    public static async Task GenerateRandomImage(HttpResponse response, TileManager tileManager)
+    public static async Task GenerateRandomImage(
+        HttpResponse response,
+        TileManager tileManager,
+        CancellationToken cancellationToken)
     {
         response.StatusCode = 200;
         response.ContentType = "image/png";
@@ -47,7 +56,7 @@ public static class ImageController
         var scale = float.Clamp(480f / int.Max(section.Width, section.Height), 0.01f, 1f);
         Console.WriteLine($"Generate random image for {coordinatePair} scale: {scale}");
         
-        await section.WriteToStream(response.Body, scale);
+        await section.WriteToPipe(response.BodyWriter, scale, cancellationToken);
         await response.CompleteAsync();
     }
 }

App/Models/GenerateImageDto.cs

@@ -69,4 +69,9 @@ public class GenerateImageDto
             yield return (fieldName, $"{fieldName} must be less than or equal to {max}.");
         }
     }
+
+    public override string ToString()
+    {
+        return $"CoordinatePair: {CanvasRect}, Crop: [{CropOffset![0]} {CropOffset[1]} {CropSize![0]} {CropSize[1]}], OutputScale: {OutputScale}";
+    }
 }

App/Program.cs

@@ -5,7 +5,7 @@ using StitchATon2.Domain;
 
 var builder = WebApplication.CreateSlimBuilder(args);
 
-using var tileManager = new TileManager(Configuration.Default);
+var tileManager = new TileManager(Configuration.Default);
 builder.Services.AddSingleton(tileManager);
 
 builder.Services.ConfigureHttpJsonOptions(options =>

App/StitchATon2.App.csproj

@@ -1,11 +1,12 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
     <PropertyGroup>
-        <TargetFramework>net8.0</TargetFramework>
+        <TargetFramework>net9.0</TargetFramework>
         <Nullable>enable</Nullable>
         <ImplicitUsings>enable</ImplicitUsings>
         <InvariantGlobalization>true</InvariantGlobalization>
         <RootNamespace>StitchATon2.App</RootNamespace>
+        <PublishAot>true</PublishAot>
     </PropertyGroup>
 
     <ItemGroup>

App/Utils.cs

@@ -1,3 +1,4 @@
+using System.IO.Pipelines;
 using StitchATon2.App.Models;
 using StitchATon2.Domain;
 using StitchATon2.Domain.ImageCreators;
@@ -14,9 +15,23 @@ public static class Utils
             dto.CropSize![0],
             dto.CropSize![1]);
 
-    public static async Task WriteToStream(this GridSection section, Stream stream, float? scale)
+    public static async Task WriteToStream(
+        this GridSection section,
+        Stream stream,
+        float? scale,
+        CancellationToken cancellationToken = default)
     {
-        var imageCreator = new ImageCreator(section);
-        await imageCreator.WriteToStream(stream, scale!.Value);
+        using var imageCreator = new DangerousImageCreator(section);
+        await imageCreator.WriteToStream(stream, scale!.Value, cancellationToken);
+    }
+
+    public static async Task WriteToPipe(
+        this GridSection section,
+        PipeWriter pipeWriter,
+        float? scale,
+        CancellationToken cancellationToken = default)
+    {
+        using var imageCreator = new DangerousImageCreator(section);
+        await imageCreator.WriteToPipe(pipeWriter, scale!.Value, cancellationToken);
     }
 }

Domain/Configuration.cs

@@ -20,25 +20,20 @@ public class Configuration
     
     public int TileCount => Columns * Rows;
 
-    public required int ImageCacheCapacity { get; init; }
-    public required int IntegralCacheCapacity { get; init; }
-
     public static Configuration Default
     {
         get
         {
-            var assetPath = Environment.GetEnvironmentVariable("ASSET_PATH_RO")!;
+            var assetPath = Environment.GetEnvironmentVariable("ASSET_PATH_RO");
             var cachePath = Path.Combine(Path.GetTempPath(), "d42df2a2-60ac-4dc3-a6b9-d4c04f2e08e6");
             return new Configuration
             {
-                AssetPath = assetPath,
+                AssetPath = assetPath!,
                 CachePath = cachePath,
                 Columns = 55,
                 Rows = 31,
                 Width = 720,
                 Height = 720,
-                ImageCacheCapacity = 5,
-                IntegralCacheCapacity = 10,
             };
         }
     }

Domain/GridSection.cs

@@ -47,5 +47,10 @@ public class GridSection
         (var rowOffset, OffsetY) = Math.DivRem(y0, config.Height);
         
         Origin = tileManager.GetTile(col0 + columnOffset, row0 + rowOffset);
+        Console.Write($"Origin: {Origin.Coordinate} ({Origin.Column}, {Origin.Row}) ");
+        Console.Write($"Tile offset: [{columnOffset} {rowOffset}] ");
+        Console.Write($"Pixel offset: [{OffsetX} {OffsetY}] ");
+        Console.Write($"Size: [{Width}x{Height}]");
+        Console.WriteLine();
     }
 }

Domain/ImageCreators/DangerousImageCreator.cs

@@ -0,0 +1,234 @@
+using System.IO.Pipelines;
+using System.Runtime.CompilerServices;
+using SixLabors.ImageSharp.PixelFormats;
+using StitchATon2.Infra;
+using StitchATon2.Infra.Buffers;
+using StitchATon2.Infra.Encoders;
+using StitchATon2.Infra.Synchronization;
+
+namespace StitchATon2.Domain.ImageCreators;
+
+public sealed class DangerousImageCreator : IDisposable
+{
+    private readonly GridSection _section;
+    private readonly IBuffer<Int32Pixel> _mmfReadBuffer;
+
+    private int FullWidth => _section.TileManager.Configuration.FullWidth;
+    private int FullHeight => _section.TileManager.Configuration.FullHeight;
+
+    private int OffsetX => _section.OffsetX;
+    private int OffsetY => _section.OffsetY;
+
+    private int Width => _section.Width;
+    private int Height => _section.Height;
+
+    private int TileWidth => _section.TileManager.Configuration.Width;
+    private int TileHeight => _section.TileManager.Configuration.Height;
+    private Tile TileOrigin => _section.Origin;
+    
+    private int RightmostPixelIndex => _section.TileManager.Configuration.RightTileIndex;
+    private int BottomPixelIndex => _section.TileManager.Configuration.BottomTileIndex;
+    
+    private TileManager TileManager => _section.TileManager;
+
+    public DangerousImageCreator(GridSection section)
+    {
+        _section = section;
+        _mmfReadBuffer = MemoryAllocator.Allocate<Int32Pixel>(TileWidth);
+    }
+    
+    ~DangerousImageCreator() => Dispose();
+
+    private Task Create(float scale, Action<IBuffer<byte>> writeRowCallback, CancellationToken cancellationToken)
+    {
+        var scaleFactor = MathF.ReciprocalEstimate(scale);
+        var targetWidth = (int)(Width / scaleFactor);
+        var targetHeight = (int)(Height / scaleFactor);
+        if (targetHeight == 0 || targetWidth == 0)
+            return Task.CompletedTask;
+
+        using var xLookup = Utils.BoundsMatrix(scaleFactor, targetWidth, FullWidth, OffsetX);
+        using var yLookup = Utils.BoundsMatrix(scaleFactor, targetHeight, FullHeight, OffsetY);
+
+        using var yStartMap = MemoryAllocator.Allocate<Int32Pixel>(targetWidth + 1);
+        using var yEndMap = MemoryAllocator.Allocate<Int32Pixel>(targetWidth + 1);
+        
+        var outputBufferSize = targetWidth * Unsafe.SizeOf<Rgb24>();
+        
+        // Use pixel referencing to eliminate type casting
+        var pxInt32 = Int32Pixel.Zero;
+        ref var px = ref pxInt32;
+        ref var rChannel = ref Unsafe.As<Int32Pixel, byte>(ref px);
+        ref var gChannel = ref Unsafe.Add(ref rChannel, 4);
+        ref var bChannel = ref Unsafe.Add(ref rChannel, 8);
+
+        var taskQueue = TaskHelper.SynchronizedTaskFactory.StartNew(() => { }, cancellationToken);
+        
+        for (var y = 1; y <= targetHeight; y++)
+        {
+            var yStart = yLookup[y - 1];
+            var yEnd = yLookup[y];
+            
+            var (localRow0, localOffsetY0) = int.DivRem(yStart, TileHeight);
+            MapRow(localRow0, localOffsetY0, xLookup, targetWidth + 1, yStartMap);
+            
+            var (localRow1, localOffsetY1) = int.DivRem(yEnd, TileHeight);
+            MapRow(localRow1, localOffsetY1, xLookup, targetWidth + 1, yEndMap);
+            
+            // Cross row
+            if (localRow0 != localRow1)
+                MapRow(localRow0, BottomPixelIndex, xLookup, targetWidth + 1, yEndMap, true);
+            
+            var outputBuffer = MemoryAllocator.Allocate<byte>(outputBufferSize);
+            ref var outputChannel = ref outputBuffer.Span[0];
+            var boxHeight = yEnd - yStart;
+            
+            for (int x1 = 1, x0 = 0; x1 <= targetWidth; x0 = x1++)
+            {
+                var xStart = xLookup[x1 - 1];
+                var xEnd = xLookup[x1];
+
+                px = yEndMap[x1];
+                px += yStartMap[x0];
+                px -= yEndMap[x0];
+                px -= yStartMap[x1];
+                px /= Math.Max(1, (xEnd - xStart) * boxHeight);
+                
+                outputChannel = rChannel;
+                outputChannel = ref Unsafe.AddByteOffset(ref outputChannel, 1);
+                
+                outputChannel = gChannel;
+                outputChannel = ref Unsafe.AddByteOffset(ref outputChannel, 1);
+                
+                outputChannel = bChannel;
+                outputChannel = ref Unsafe.AddByteOffset(ref outputChannel, 1);
+            }
+
+            if (cancellationToken.IsCancellationRequested)
+            {
+                outputBuffer.Dispose();
+                return Task.FromCanceled(cancellationToken);
+            }
+            
+            cancellationToken.Register(outputBuffer.Dispose);
+            taskQueue = taskQueue
+                .ContinueWith(
+                    _ => writeRowCallback.Invoke(outputBuffer),
+                    cancellationToken,
+                    TaskContinuationOptions.OnlyOnRanToCompletion,
+                    TaskScheduler.Current);
+        }
+
+        return taskQueue;
+    }
+
+    public async Task WriteToPipe(PipeWriter outputPipe, float scale, CancellationToken cancellationToken = default)
+    {
+        var scaleFactor = MathF.ReciprocalEstimate(scale);
+        var targetWidth = (int)(Width / scaleFactor);
+        var targetHeight = (int)(Height / scaleFactor);
+        if (targetHeight == 0 || targetWidth == 0)
+            return;
+        
+        var encoder = new PngPipeEncoder(outputPipe, targetWidth, targetHeight);
+        encoder.WriteHeader();
+        
+        await Create(scale, 
+            output => encoder
+                .WriteDataAsync(output, cancellationToken: cancellationToken)
+                .Wait(cancellationToken),
+            cancellationToken);
+        
+        await encoder.WriteEndOfFileAsync(cancellationToken);
+    }
+
+    public async Task WriteToStream(Stream outputStream, float scale, CancellationToken cancellationToken = default)
+    {
+        var scaleFactor = MathF.ReciprocalEstimate(scale);
+        var targetWidth = (int)(Width / scaleFactor);
+        var targetHeight = (int)(Height / scaleFactor);
+        if (targetHeight == 0 || targetWidth == 0)
+            return;
+        
+        var encoder = new PngStreamEncoder(outputStream, targetWidth, targetHeight);
+        await encoder.WriteHeader(cancellationToken);
+        
+        await Create(scale, 
+            output => encoder
+                .WriteDataAsync(output, cancellationToken: cancellationToken)
+                .Wait(cancellationToken),
+            cancellationToken);
+        
+        await encoder.WriteEndOfFileAsync(cancellationToken);
+    }
+    
+    private void MapRow(
+        int rowOffset,
+        int yOffset,
+        IBuffer<int> boundsMatrix,
+        int count,
+        IBuffer<Int32Pixel> destination,
+        bool appendMode = false)
+    {
+        var currentTile = TileManager.TryGetAdjacent(TileOrigin, 0, rowOffset);
+        if (currentTile == null)
+        {
+            if (appendMode) return;
+            for (var i = 0; i < count; i++)
+                destination[i] = Int32Pixel.Zero;
+
+            return;
+        }
+        
+        var sourceMap = boundsMatrix.Span[..count];
+        var xAdder = Int32Pixel.Zero;
+        var xOffset = 0;
+        var written = 0;
+        var destinationSpan = destination.Span;
+        var readBufferSpan = _mmfReadBuffer.Span;
+        
+        while (true)
+        {
+            currentTile.Integral.Acquire(yOffset, readBufferSpan);
+            int localX;
+
+            if (appendMode)
+            {
+                while (written < sourceMap.Length && (localX = sourceMap[written] - xOffset) < TileWidth)
+                {
+                    destinationSpan[written] += readBufferSpan[localX];
+                    destinationSpan[written] += xAdder;
+                    written++;
+                }
+            }
+            else
+            {
+                while (written < sourceMap.Length && (localX = sourceMap[written] - xOffset) < TileWidth)
+                {
+                    destinationSpan[written] = readBufferSpan[localX];
+                    destinationSpan[written] += xAdder;
+                    written++;
+                }
+            }
+            
+            if (written >= sourceMap.Length)
+                break;
+            
+            currentTile = TileManager.TryGetAdjacent(currentTile, 1, 0);
+            if (currentTile == null)
+            {
+                destinationSpan[written] = destinationSpan[written - 1];
+                break;
+            }
+
+            xAdder += readBufferSpan[RightmostPixelIndex];
+            xOffset += TileWidth;
+        }
+    }
+
+    public void Dispose()
+    {
+        _mmfReadBuffer.Dispose();
+        GC.SuppressFinalize(this);
+    }
+}

Domain/ImageCreators/ImageCreator.cs

@@ -1,160 +0,0 @@
-using System.Runtime.CompilerServices;
-using SixLabors.ImageSharp.PixelFormats;
-using StitchATon2.Infra;
-using StitchATon2.Infra.Buffers;
-using StitchATon2.Infra.Encoders;
-
-namespace StitchATon2.Domain.ImageCreators;
-
-public class ImageCreator : IDisposable
-{
-    private readonly GridSection _section;
-
-    private int FullWidth => _section.TileManager.Configuration.FullWidth;
-    private int FullHeight => _section.TileManager.Configuration.FullHeight;
-
-    private int OffsetX => _section.OffsetX;
-    private int OffsetY => _section.OffsetY;
-
-    private int Width => _section.Width;
-    private int Height => _section.Height;
-
-    private int TileWidth => _section.TileManager.Configuration.Width;
-    private int TileHeight => _section.TileManager.Configuration.Height;
-    private Tile TileOrigin => _section.Origin;
-    
-    private int RightmostPixelIndex => _section.TileManager.Configuration.RightTileIndex;
-    private int BottomPixelIndex => _section.TileManager.Configuration.BottomTileIndex;
-    
-    private TileManager TileManager => _section.TileManager;
-
-    private readonly ArrayOwner<Int32Pixel> _mmfReadBuffer;
-
-    public ImageCreator(GridSection section)
-    {
-        _section = section;
-        _mmfReadBuffer = MemoryAllocator.AllocateArray<Int32Pixel>(TileWidth);
-    }
-    
-    public async Task WriteToStream(Stream writableStream, float scale)
-    {
-        var scaleFactor = MathF.ReciprocalEstimate(scale);
-        var targetWidth = (int)(Width / scaleFactor);
-        var targetHeight = (int)(Height / scaleFactor);
-        
-        var encoder = new PngStreamEncoder(writableStream, targetWidth, targetHeight);
-        await encoder.WriteHeader();
-
-        var outputBufferSize = targetWidth * Unsafe.SizeOf<Rgb24>();
-        using var outputBuffer = MemoryAllocator.AllocateManaged<byte>(outputBufferSize);
-        
-        using var xLookup = Utils.BoundsMatrix(scaleFactor, targetWidth, FullWidth, OffsetX);
-        using var yLookup = Utils.BoundsMatrix(scaleFactor, targetHeight, FullHeight, OffsetY);
-
-        using var yStartMap = MemoryAllocator.Allocate<Int32Pixel>(targetWidth);
-        using var yEndMap = MemoryAllocator.Allocate<Int32Pixel>(targetWidth);
-
-        var yStart = OffsetY;
-        Task? outputTask = null;
-        for (var y = 0; y < targetHeight; y++)
-        {
-            var yEnd = yLookup[y];
-            
-            var (localRow0, localOffsetY0) = int.DivRem(yStart, TileHeight);
-            MapRow(localRow0, localOffsetY0, xLookup.Span[..targetWidth], yStartMap);
-            
-            var (localRow1, localOffsetY1) = int.DivRem(yEnd, TileHeight);
-            MapRow(localRow1, localOffsetY1, xLookup.Span[..targetWidth], yEndMap);
-            
-            if (localRow0 != localRow1)
-            {
-                MapRowAppend(localRow0, BottomPixelIndex, xLookup.Span[..targetWidth], yEndMap);
-            }
-
-            if(outputTask != null)
-                await outputTask;
-
-            int xStart = OffsetX, x0 = 0;
-            for (int x1 = 0, i = 0; x1 < targetWidth; x1++)
-            {
-                var xEnd = xLookup[x1];
-
-                var pixel = yEndMap[x1];
-                pixel += yStartMap[x0];
-                pixel -= yEndMap[x0];
-                pixel -= yStartMap[x1];
-                
-                pixel /= Math.Max(1, (xEnd - xStart) * (yEnd - yStart));
-                outputBuffer.Memory.Span[i++] = (byte)pixel.R;
-                outputBuffer.Memory.Span[i++] = (byte)pixel.G;
-                outputBuffer.Memory.Span[i++] = (byte)pixel.B;
-                
-                xStart = xEnd;
-                x0 = x1;
-            }
-            
-            outputTask = encoder.WriteData(outputBuffer.Memory[..outputBufferSize]);
-            yStart = yEnd;
-        }
-
-        await encoder.WriteEndOfFile();
-    }
-    
-    private void MapRow(int rowOffset, int yOffset, Span<int> sourceMap, IBuffer<Int32Pixel> destination)
-    {
-        var currentTile = TileManager.GetAdjacent(TileOrigin, 0, rowOffset);
-        var xAdder = Int32Pixel.Zero;
-        var xOffset = 0;
-        var written = 0;
-        while (true)
-        {
-            currentTile.Integral.Acquire(yOffset, _mmfReadBuffer.Array);
-            int localX;
-            while (written < sourceMap.Length && (localX = sourceMap[written] - xOffset) < TileWidth)
-            {
-                destination.Span[written] = _mmfReadBuffer[localX];
-                destination.Span[written] += xAdder;
-                written++;
-            }
-
-            if (written >= sourceMap.Length)
-                break;
-
-            xAdder += _mmfReadBuffer[RightmostPixelIndex];
-            xOffset += TileWidth;
-            currentTile = TileManager.GetAdjacent(currentTile, 1, 0);
-        }
-    }
-
-    private void MapRowAppend(int rowOffset, int yOffset, Span<int> sourceMap, IBuffer<Int32Pixel> destination)
-    {
-        var currentTile = TileManager.GetAdjacent(TileOrigin, 0, rowOffset);
-        var xAdder = Int32Pixel.Zero;
-        var xOffset = 0;
-        var written = 0;
-        while (true)
-        {
-            currentTile.Integral.Acquire(yOffset, _mmfReadBuffer.Array);
-            int localX;
-            while (written < sourceMap.Length && (localX = sourceMap[written] - xOffset) < TileWidth)
-            {
-                destination.Span[written] += _mmfReadBuffer[localX];
-                destination.Span[written] += xAdder;
-                written++;
-            }
-
-            if (written >= sourceMap.Length)
-                break;
-
-            xAdder += _mmfReadBuffer[RightmostPixelIndex];
-            xOffset += TileWidth;
-            currentTile = TileManager.GetAdjacent(currentTile, 1, 0);
-        }
-    }
-
-    public void Dispose()
-    {
-        _mmfReadBuffer.Dispose();
-        GC.SuppressFinalize(this);
-    }
-}

Domain/StitchATon2.Domain.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>net8.0</TargetFramework>
+        <TargetFramework>net9.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
         <Nullable>enable</Nullable>
     </PropertyGroup>

Domain/TileManager.cs

@@ -5,29 +5,26 @@ using StitchATon2.Infra.Buffers;
 
 namespace StitchATon2.Domain;
 
-public sealed class TileManager : IDisposable
+public sealed class TileManager
 {
-    private readonly IMemoryOwner<Tile> _tiles;
+    private readonly Tile[] _tiles;
     
     public Configuration Configuration { get; }
 
     public TileManager(Configuration config)
     {
         Configuration = config;
-        _tiles = MemoryAllocator.AllocateManaged<Tile>(config.TileCount);
-        var tilesSpan = _tiles.Memory.Span;
+        _tiles = new Tile[Configuration.TileCount];
         for (var id = 0; id < config.TileCount; id++)
-            tilesSpan[id] = CreateTile(id);
+            _tiles[id] = CreateTile(id);
         
         Console.WriteLine("Tile manager created");
     }
 
-    ~TileManager() => Dispose();
-
     private Tile CreateTile(int id)
     {
         var (row, column) = int.DivRem(id, Configuration.Columns);
-        var coordinate = $"{Utils.GetSBSNotation(++row)}{++column}";
+        var coordinate = $"{Utils.GetSbsNotationRow(++row)}{++column}";
         return new Tile
         {
             Id = id,
@@ -47,14 +44,14 @@ public sealed class TileManager : IDisposable
     private int GetId(int column, int row) => column - 1 + (row - 1) * Configuration.Columns;
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public Tile GetTile(int id) => _tiles.Memory.Span[id];
+    public Tile GetTile(int id) => _tiles[id];
 
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public Tile GetTile(int column, int row) => GetTile(GetId(column, row));
 
     public Tile GetTile(string coordinate)
     {
-        var (column, row) = Utils.GetSBSCoordinate(coordinate);
+        var (column, row) = Utils.GetSbsNotationCoordinate(coordinate);
         return GetTile(column, row);
     }
     
@@ -99,10 +96,4 @@ public sealed class TileManager : IDisposable
             cropY,
             cropWidth,
             cropHeight);
-
-    public void Dispose()
-    {
-        _tiles.Dispose();
-        GC.SuppressFinalize(this);
-    }
 }

Domain/Utils.cs

@@ -9,7 +9,7 @@ namespace StitchATon2.Domain;
 public static class Utils
 {
     [Pure]
-    public static string GetSBSNotation(int row)
+    public static string GetSbsNotationRow(int row)
         => row <= 26
             ? new string([(char)(row + 'A' - 1)])
             : new string(['A', (char)(row + 'A' - 27)]);
@@ -20,7 +20,8 @@ public static class Utils
         return (a + b - 1) / b;
     }
     
-    public static (int Column, int Row) GetSBSCoordinate(string coordinate)
+    [Pure]
+    public static (int Column, int Row) GetSbsNotationCoordinate(string coordinate)
     {
         var column = coordinate[^1] - '0';
         if(char.IsDigit(coordinate[^2]))
@@ -33,26 +34,31 @@ public static class Utils
         return (column, row);
     }
     
-    
+    /// <summary>
+    /// Performs a SIMD-accelerated calculation that generates a buffer of bounded, scaled indices.
+    /// </summary>
+    /// <param name="scaleFactor">The amount by which to scale the sequence values.</param>
+    /// <param name="length">The total number of scalar values to generate.</param>
+    /// <param name="max">Upper limit (exclusive) for clamping values.</param>
+    /// <param name="offset">The offset to apply before clamping.</param>
     public static IBuffer<int> BoundsMatrix(float scaleFactor, int length, int max, int offset)
     {
-        var vectorSize = DivCeil(length, Vector<float>.Count);
+        var vectorSize = DivCeil(length + 1, Vector<float>.Count);
         using var buffer = MemoryAllocator.Allocate<Vector<float>>(vectorSize);
 
         var span = buffer.Span;
         var vectorMin = Vector<int>.Zero;
-        var vectorOffset = new Vector<int>(offset - 1);
+        var vectorOffset = new Vector<int>(offset);
         var vectorMax = new Vector<int>(max - 1);
         var vectorScale = new Vector<float>(scaleFactor);
 
-        var vectorSequence = SequenceVector(0f, 1f);
+        var vectorSequence = Vector.CreateSequence(0f, 1f);
 
-        var seq = 0f;
+        var seq = -1f;
         for (var i = 0; i < vectorSize; i++, seq += Vector<float>.Count)
         {
             var sequence = new Vector<float>(seq) + vectorSequence;
-            span[i] = Vector.Multiply(sequence, vectorScale);
-            span[i] = Vector.Add(span[i], vectorScale);
+            span[i] = Vector.FusedMultiplyAdd(sequence, vectorScale, vectorScale);
             span[i] = Vector.Ceiling(span[i]);
         }
         
@@ -62,23 +68,9 @@ public static class Utils
         {
             resultSpan[i] = Vector.ConvertToInt32(span[i]);
             resultSpan[i] = Vector.Add(resultSpan[i], vectorOffset);
-            resultSpan[i] = Vector.Min(resultSpan[i], vectorMax);
-            resultSpan[i] = Vector.Max(resultSpan[i], vectorMin);
+            resultSpan[i] = Vector.ClampNative(resultSpan[i], vectorMin, vectorMax);
         }
 
         return result;
     }
-
-    private static Vector<float> SequenceVector(float start, float step)
-    {
-        var vector = Vector<float>.Zero;
-        ref var reference = ref Unsafe.As<Vector<float>, float>(ref vector);
-        for (var i = 0; i < Vector<float>.Count; i++)
-        {
-            ref var current = ref Unsafe.Add(ref reference, i);
-            current = start + step * i;
-        }
-
-        return vector;
-    }
 }

Infra/Buffers/ArrayOwner.cs

@@ -7,10 +7,11 @@ public class ArrayOwner<T> : IBuffer<T> where T : unmanaged
     private readonly ArrayPool<T> _owner;
     private readonly T[] _buffer;
 
-    public ArrayOwner(ArrayPool<T> owner, int size)
+    public ArrayOwner(ArrayPool<T> owner, int length)
     {
         _owner = owner;
-        _buffer = owner.Rent(size);
+        _buffer = owner.Rent(length);
+        Length = length;
     }
     
     ~ArrayOwner() => Dispose();
@@ -23,7 +24,10 @@ public class ArrayOwner<T> : IBuffer<T> where T : unmanaged
 
     public ref T this[int index] => ref _buffer[index];
 
-    public Span<T> Span => _buffer;
+    public Span<T> Span => _buffer.AsSpan(0, Length);
+    public Memory<T> Memory => _buffer.AsMemory(0, Length);
 
     public T[] Array => _buffer;
+
+    public int Length { get; }
 }

Infra/Buffers/IBuffer.cs

@@ -5,4 +5,8 @@ public interface IBuffer<T> : IDisposable where T : unmanaged
     ref T this[int index] { get; }
         
     Span<T> Span { get; }
+        
+    Memory<T> Memory { get; }
+    
+    int Length { get; }
 }

Infra/Buffers/ImmovableMemory.cs

@@ -0,0 +1,51 @@
+using System.Buffers;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace StitchATon2.Infra.Buffers;
+
+internal sealed unsafe class ImmovableMemory<T> : MemoryManager<T>, IBuffer<T> where T : unmanaged
+{
+    internal readonly T* Pointer;
+    private bool _disposed;
+
+    public ImmovableMemory(int length)
+    {
+        Pointer = (T*)NativeMemory.Alloc((nuint)length, (nuint)Unsafe.SizeOf<T>());
+        Length = length;
+    }
+    
+    protected override void Dispose(bool disposing)
+    {
+        if (_disposed) return;
+        NativeMemory.Free(Pointer);
+        _disposed = true;
+    }
+
+    public override Span<T> GetSpan()
+        => _disposed 
+            ? throw new ObjectDisposedException(nameof(ImmovableMemory<T>)) 
+            : new Span<T>(Pointer, Length);
+
+    public override MemoryHandle Pin(int elementIndex = 0)
+        => _disposed
+            ? throw new ObjectDisposedException(nameof(ImmovableMemory<T>))
+            : new MemoryHandle(Pointer + elementIndex);
+
+    public override void Unpin()
+    {
+    }
+
+    public ref T this[int index]
+    {
+        get
+        {
+            if (_disposed) throw new ObjectDisposedException(nameof(ImmovableMemory<T>));
+            return ref Unsafe.AsRef<T>(Pointer + index);
+        }
+    }
+
+    public Span<T> Span => GetSpan();
+    
+    public int Length { get; }
+}

Infra/Buffers/MemoryAllocator.cs

@@ -1,15 +1,36 @@
 using System.Buffers;
+using System.Runtime.CompilerServices;
 
 namespace StitchATon2.Infra.Buffers;
 
 public static class MemoryAllocator
 {
     public static IBuffer<T> Allocate<T>(int count) where T : unmanaged
-        => new UnmanagedMemory<T>(count);
+        => new ImmovableMemory<T>(count);
     
     public static IMemoryOwner<T> AllocateManaged<T>(int count)
         => MemoryPool<T>.Shared.Rent(count);
     
     public static ArrayOwner<T> AllocateArray<T>(int count) where T : unmanaged
         => new(ArrayPool<T>.Shared, count);
+
+    public static unsafe IBuffer<T> Clone<T>(this IBuffer<T> buffer) where T : unmanaged
+    {
+        if (buffer is not ImmovableMemory<T> unmanagedMemory)
+            throw new NotSupportedException();
+        
+        var newBuffer = new ImmovableMemory<T>(buffer.Length);
+        var byteCount = (uint)(Unsafe.SizeOf<T>() * buffer.Length);
+        Unsafe.CopyBlock(newBuffer.Pointer, unmanagedMemory.Pointer, byteCount);
+        return newBuffer;
+    }
+
+    public static unsafe void Copy<T>(this IBuffer<T> source, IBuffer<T> destination, int count) where T : unmanaged
+    {
+        if (source is not ImmovableMemory<T> sourceBuffer || destination is not ImmovableMemory<T> destinationBuffer)
+            throw new NotSupportedException();
+        
+        var byteCount = (uint)(Unsafe.SizeOf<T>() * count);
+        Unsafe.CopyBlock(destinationBuffer.Pointer, sourceBuffer.Pointer, byteCount);
+    }
 }

Infra/Buffers/PooledMemoryStream.cs

@@ -0,0 +1,102 @@
+using System.Buffers;
+
+namespace StitchATon2.Infra.Buffers;
+
+public class PooledMemoryStream : Stream
+{
+    private byte[] _buffer;
+    private int _length;
+    private int _position;
+    private readonly ArrayPool<byte> _pool;
+    private bool _disposed;
+
+    public PooledMemoryStream(int initialCapacity = 1024, ArrayPool<byte>? pool = null)
+    {
+        _pool = pool ?? ArrayPool<byte>.Shared;
+        _buffer = _pool.Rent(initialCapacity);
+    }
+
+    public override bool CanRead => !_disposed;
+    public override bool CanSeek => !_disposed;
+    public override bool CanWrite => !_disposed;
+    public override long Length => _length;
+    public override long Position
+    {
+        get => _position;
+        set
+        {
+            if (_disposed) throw new ObjectDisposedException(nameof(PooledMemoryStream));
+            if (value < 0 || value > int.MaxValue) throw new ArgumentOutOfRangeException();
+            _position = (int)value;
+        }
+    }
+
+    public byte[] GetBuffer() => _buffer;
+    public ArraySegment<byte> GetWrittenSegment() => new(_buffer, 0, _length);
+
+    public override void Flush() { /* no-op */ }
+
+    public override int Read(byte[] buffer, int offset, int count)
+    {
+        if (_disposed) throw new ObjectDisposedException(nameof(PooledMemoryStream));
+        int available = _length - _position;
+        int toRead = Math.Min(count, available);
+        Buffer.BlockCopy(_buffer, _position, buffer, offset, toRead);
+        _position += toRead;
+        return toRead;
+    }
+
+    public override void Write(byte[] buffer, int offset, int count)
+    {
+        if (_disposed) throw new ObjectDisposedException(nameof(PooledMemoryStream));
+        EnsureCapacity(_position + count);
+        Buffer.BlockCopy(buffer, offset, _buffer, _position, count);
+        _position += count;
+        _length = Math.Max(_length, _position);
+    }
+
+    public override long Seek(long offset, SeekOrigin origin)
+    {
+        if (_disposed) throw new ObjectDisposedException(nameof(PooledMemoryStream));
+        int newPos = origin switch
+        {
+            SeekOrigin.Begin => (int)offset,
+            SeekOrigin.Current => _position + (int)offset,
+            SeekOrigin.End => _length + (int)offset,
+            _ => throw new ArgumentOutOfRangeException()
+        };
+        if (newPos < 0) throw new IOException("Negative position");
+        _position = newPos;
+        return _position;
+    }
+
+    public override void SetLength(long value)
+    {
+        if (_disposed) throw new ObjectDisposedException(nameof(PooledMemoryStream));
+        if (value < 0 || value > int.MaxValue) throw new ArgumentOutOfRangeException();
+        EnsureCapacity((int)value);
+        _length = (int)value;
+        if (_position > _length) _position = _length;
+    }
+
+    private void EnsureCapacity(int size)
+    {
+        if (size <= _buffer.Length) return;
+        int newSize = Math.Max(size, _buffer.Length * 2);
+        byte[] newBuffer = _pool.Rent(newSize);
+        Buffer.BlockCopy(_buffer, 0, newBuffer, 0, _length);
+        _pool.Return(_buffer, clearArray: true);
+        _buffer = newBuffer;
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        if (!_disposed)
+        {
+            _pool.Return(_buffer, clearArray: true);
+            _buffer = Array.Empty<byte>();
+            _disposed = true;
+        }
+        base.Dispose(disposing);
+    }
+}

Infra/Buffers/UnmanagedMemory.cs

@@ -3,26 +3,38 @@ using System.Runtime.InteropServices;
 
 namespace StitchATon2.Infra.Buffers;
 
+/// <summary>
+/// Provide non-thread safe anti GC contiguous memory. 
+/// </summary>
+/// <typeparam name="T"></typeparam>
+[Obsolete("Use immovable memory instead")]
 internal sealed unsafe class UnmanagedMemory<T> : IBuffer<T> where T : unmanaged
 {
-    private readonly void* _pointer;
-    private readonly int _count;
+    internal readonly T* Pointer;
+    private bool _disposed;
 
-    public ref T this[int index] => ref Unsafe.AsRef<T>((T*)_pointer + index); // *((T*)_pointer + index);
+    public Memory<T> Memory => throw new NotImplementedException();
+    public int Length { get; }
 
-    public Span<T> Span => new(_pointer, _count);
+    public ref T this[int index] => ref Unsafe.AsRef<T>(Pointer + index);
 
-    public UnmanagedMemory(int count)
+    public Span<T> Span => new(Pointer, Length);
+
+    public UnmanagedMemory(int length)
     {
-        _pointer = NativeMemory.Alloc((nuint)count, (nuint)Unsafe.SizeOf<T>());
-        _count = count;
+        Pointer = (T*)NativeMemory.Alloc((nuint)length, (nuint)Unsafe.SizeOf<T>());
+        Length = length;
     }
     
     ~UnmanagedMemory() => Dispose();
 
     public void Dispose()
     {
-        NativeMemory.Free(_pointer);
+        if (!_disposed)
+        {
+            NativeMemory.Free(Pointer);
             GC.SuppressFinalize(this);
+            _disposed = true;
+        }
     }
 }

Infra/Encoders/Crc32.cs

@@ -15,6 +15,17 @@ public static class Crc32
         return ~crc;
     }
 
+    public static uint Compute(Stream stream, int count, uint initial = 0xFFFFFFFF)
+    {
+        uint crc = initial;
+        while (count-- > 0)
+        {
+            crc = Table[(crc ^ stream.ReadByte()) & 0xFF] ^ (crc >> 8);
+        }
+        
+        return ~crc;
+    }
+
     private static uint[] GenerateTable()
     {
         const uint poly = 0xEDB88320;

Infra/Encoders/PngPipeEncoder.cs

@@ -0,0 +1,144 @@
+using System.Buffers;
+using System.Buffers.Binary;
+using System.IO.Compression;
+using System.IO.Pipelines;
+using StitchATon2.Infra.Buffers;
+
+namespace StitchATon2.Infra.Encoders;
+
+public class PngPipeEncoder : IDisposable
+{
+    private const int BufferSize = 8 * 1024;
+    private const int FlushThreshold = 1024;
+    private const int PipeChunkThreshold = 16 * 1024;
+    
+    private readonly PipeWriter _outputPipe;
+    private readonly MemoryStream _memoryStream;
+    private readonly int _width;
+    private readonly int _height;
+
+    private readonly ZLibStream _zlibStream;
+    private bool _disposed;
+    private bool _shouldFlush;
+    
+    public PngPipeEncoder(PipeWriter outputPipe, int width, int height)
+    {
+        _outputPipe = outputPipe;
+        _width = width;
+        _height = height;
+        _memoryStream = new MemoryStream(BufferSize * 2);
+        _zlibStream = new ZLibStream(_memoryStream, CompressionLevel.Optimal, leaveOpen: true);
+        _memoryStream.SetLength(8);
+        _memoryStream.Position = 8;
+    }
+
+    ~PngPipeEncoder() => Dispose();
+
+    public void WriteHeader()
+    {
+        Span<byte> headerBytes = [
+            0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, // PNG Signature
+            0x00, 0x00, 0x00, 0x0D, // Length
+            
+            // IHDR chunk
+            0x49, 0x48, 0x44, 0x52, // IHDR
+            0x00, 0x00, 0x00, 0x00, // Reserve to write Width
+            0x00, 0x00, 0x00, 0x00, // Reserve to write Height
+            0x08, // Bit depth
+            0x02, // Color type
+            0x00, // Compression method
+            0x00, // Filter method
+            0x00, // Interlace method
+            0x00, 0x00, 0x00, 0x00, // Reserve to write CRC-32
+        ];
+        
+        BinaryPrimitives.WriteInt32BigEndian(headerBytes[16..], _width);
+        BinaryPrimitives.WriteInt32BigEndian(headerBytes[20..], _height);
+        var crc = Crc32.Compute(headerBytes.Slice(12, 17));
+        
+        BinaryPrimitives.WriteUInt32BigEndian(headerBytes[29..], crc);
+        
+        _outputPipe.Write(headerBytes);
+    }
+
+    public async Task WriteDataAsync(IBuffer<byte> buffer, bool disposeBuffer = true, CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            _zlibStream.Write([0]);
+
+            var offset = 0;
+            while (buffer.Length - offset > FlushThreshold)
+            {
+                _zlibStream.Write(buffer.Span.Slice(offset, FlushThreshold));
+                await _zlibStream.FlushAsync(cancellationToken);
+                offset += FlushThreshold;
+                if (_memoryStream.Length >= BufferSize)
+                    await FlushAsync(cancellationToken);
+            }
+
+            if (buffer.Length > offset)
+            {
+                _zlibStream.Write(buffer.Span[offset..]);
+                await _zlibStream.FlushAsync(cancellationToken);
+                _shouldFlush = true;
+            }
+        }
+        finally
+        {
+            if(disposeBuffer)
+                buffer.Dispose();
+        }
+    }
+
+    private async Task FlushAsync(CancellationToken cancellationToken)
+    {
+        await _zlibStream.FlushAsync(cancellationToken);
+        var dataSize = (int)(_memoryStream.Length - 8);
+
+        _memoryStream.Write("\0\0\0\0"u8);
+
+        _memoryStream.Position = 4;
+        _memoryStream.Write("IDAT"u8);
+
+        var buffer = _memoryStream.GetBuffer();
+        BinaryPrimitives.WriteInt32BigEndian(buffer, dataSize);
+
+        // write Crc
+        var crc = Crc32.Compute(buffer.AsSpan(4, dataSize + 4));
+        BinaryPrimitives.WriteUInt32BigEndian(buffer.AsSpan(dataSize + 8), crc);
+        
+        _outputPipe.Write(buffer.AsSpan(0, dataSize + 12));
+        await _outputPipe.FlushAsync(cancellationToken);
+        
+        _memoryStream.SetLength(8);
+        _memoryStream.Position = 8;
+        _shouldFlush = false;
+    }
+
+    public async Task WriteEndOfFileAsync(CancellationToken cancellationToken = default)
+    {
+        if(_shouldFlush)
+            await FlushAsync(cancellationToken);
+        
+        Span<byte> endChunk = [
+            0x00, 0x00, 0x00, 0x00, // Length
+            0x49, 0x45, 0x4E, 0x44, // IEND
+            0xAE, 0x42, 0x60, 0x82, // Crc
+        ];
+        
+        _outputPipe.Write(endChunk);
+        Dispose();
+    }
+
+    public void Dispose()
+    {
+        if (!_disposed)
+        {
+            _zlibStream.Dispose();
+            _memoryStream.Dispose();
+            _disposed = true;
+            GC.SuppressFinalize(this);
+        }
+    }
+}

Infra/Encoders/PngStreamEncoder.cs

@@ -1,5 +1,6 @@
 using System.Buffers.Binary;
 using System.IO.Compression;
+using StitchATon2.Infra.Buffers;
 
 namespace StitchATon2.Infra.Encoders;
 
@@ -30,7 +31,7 @@ public class PngStreamEncoder : IDisposable, IAsyncDisposable
 
     ~PngStreamEncoder() => Dispose();
 
-    public async Task WriteHeader()
+    public async Task WriteHeader(CancellationToken cancellationToken = default)
     {
         byte[] headerBytes = [
             0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, // PNG Signature
@@ -54,34 +55,42 @@ public class PngStreamEncoder : IDisposable, IAsyncDisposable
         
         BinaryPrimitives.WriteUInt32BigEndian(headerBytes.AsSpan(29), crc);
         
-        await _stream.WriteAsync(headerBytes);
+        await _stream.WriteAsync(headerBytes, cancellationToken);
     }
 
-    public async Task WriteData(Memory<byte> data)
+    public async Task WriteDataAsync(IBuffer<byte> buffer, bool disposeBuffer = true, CancellationToken cancellationToken = default)
+    {
+        try
         {
             _zlibStream.Write([0]);
 
-        var dataSlice = data;
+            var dataSlice = buffer.Memory;
             while (dataSlice.Length > FlushThreshold)
             {
-            await _zlibStream.WriteAsync(dataSlice[..FlushThreshold]);
-            await _zlibStream.FlushAsync();
+                await _zlibStream.WriteAsync(dataSlice[..FlushThreshold], cancellationToken);
+                await _zlibStream.FlushAsync(cancellationToken);
                 dataSlice = dataSlice[FlushThreshold..];
                 if (_memoryStream.Length >= BufferSize)
-                await Flush();
+                    await FlushAsync(cancellationToken);
             }
 
             if (dataSlice.Length > 0)
             {
-            await _zlibStream.WriteAsync(dataSlice);
-            await _zlibStream.FlushAsync();
+                await _zlibStream.WriteAsync(dataSlice, cancellationToken);
+                await _zlibStream.FlushAsync(cancellationToken);
                 _shouldFlush = true;
             }
         }
-
-    private async Task Flush()
+        finally
         {
-        await _zlibStream.FlushAsync();
+            if(disposeBuffer)
+                buffer.Dispose();
+        }
+    }
+
+    private async Task FlushAsync(CancellationToken cancellationToken)
+    {
+        await _zlibStream.FlushAsync(cancellationToken);
         var dataSize = (int)(_memoryStream.Length - 8);
 
         _memoryStream.Write("\0\0\0\0"u8);
@@ -96,16 +105,16 @@ public class PngStreamEncoder : IDisposable, IAsyncDisposable
         var crc = Crc32.Compute(buffer.AsSpan(4, dataSize + 4));
         BinaryPrimitives.WriteUInt32BigEndian(buffer.AsSpan(dataSize + 8), crc);
             
-        await _stream.WriteAsync(buffer.AsMemory(0, dataSize + 12));
+        await _stream.WriteAsync(buffer.AsMemory(0, dataSize + 12), cancellationToken);
         _memoryStream.SetLength(8);
         _memoryStream.Position = 8;
         _shouldFlush = false;
     }
 
-    public async ValueTask WriteEndOfFile()
+    public async ValueTask WriteEndOfFileAsync(CancellationToken cancellationToken = default)
     {
         if(_shouldFlush)
-            await Flush();
+            await FlushAsync(cancellationToken);
         
         var endChunk = new byte[] {
             0x00, 0x00, 0x00, 0x00, // Length
@@ -113,7 +122,7 @@ public class PngStreamEncoder : IDisposable, IAsyncDisposable
             0xAE, 0x42, 0x60, 0x82, // Crc
         };
         
-        await _stream.WriteAsync(endChunk);
+        await _stream.WriteAsync(endChunk, cancellationToken);
         await DisposeAsync();
     }
 

Infra/Encoders/UnsafePngEncoder.cs

@@ -0,0 +1,166 @@
+using System.Buffers;
+using System.Buffers.Binary;
+using System.IO.Compression;
+using System.IO.Pipelines;
+using StitchATon2.Infra.Buffers;
+
+namespace StitchATon2.Infra.Encoders;
+
+public class UnsafePngEncoder : IDisposable
+{
+    private const int BufferSize = 8 * 1024;
+    private const int FlushThreshold = 1024;
+    private const int PipeChunkThreshold = 16 * 1024;
+    
+    private readonly PipeWriter _outputPipe;
+    private readonly int _width;
+    private readonly int _height;
+
+    private MemoryHandle? _memoryHandle;
+    private readonly RawPointerStream _memoryStream;// = new RawPointerStream();
+    private ZLibStream? _zlibStream;// = new ZLibStream(_memoryStream, CompressionLevel.Optimal, leaveOpen: true);
+    private bool _disposed;
+    private bool _shouldFlush;
+    
+    public UnsafePngEncoder(PipeWriter outputPipe, int width, int height)
+    {
+        _outputPipe = outputPipe;
+        _width = width;
+        _height = height;
+
+        _memoryStream = new RawPointerStream();
+    }
+
+    ~UnsafePngEncoder() => Dispose();
+
+    public void WriteHeader()
+    {
+        Span<byte> headerBytes = [
+            0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A, // PNG Signature
+            0x00, 0x00, 0x00, 0x0D, // Length
+            
+            // IHDR chunk
+            0x49, 0x48, 0x44, 0x52, // IHDR
+            0x00, 0x00, 0x00, 0x00, // Reserve to write Width
+            0x00, 0x00, 0x00, 0x00, // Reserve to write Height
+            0x08, // Bit depth
+            0x02, // Color type
+            0x00, // Compression method
+            0x00, // Filter method
+            0x00, // Interlace method
+            0x00, 0x00, 0x00, 0x00, // Reserve to write CRC-32
+        ];
+        
+        BinaryPrimitives.WriteInt32BigEndian(headerBytes[16..], _width);
+        BinaryPrimitives.WriteInt32BigEndian(headerBytes[20..], _height);
+        var crc = Crc32.Compute(headerBytes.Slice(12, 17));
+        
+        BinaryPrimitives.WriteUInt32BigEndian(headerBytes[29..], crc);
+        
+        _outputPipe.Write(headerBytes);
+    }
+
+    private unsafe void Initialize()
+    {
+        if (_memoryHandle == null)
+        {
+            var memory = _outputPipe.GetMemory(PipeChunkThreshold);
+            var handle = memory.Pin();
+            _memoryStream.Initialize((byte*)handle.Pointer, 0, memory.Length);
+            _memoryHandle = handle;
+            
+            _memoryStream.SetLength(8);
+            _memoryStream.Position = 8;
+            _zlibStream = new ZLibStream(_memoryStream, CompressionLevel.Optimal, true);
+        }
+    }
+
+    public async Task WriteDataAsync(IBuffer<byte> buffer, bool disposeBuffer = true, CancellationToken cancellationToken = default)
+    {
+        Initialize();
+        _zlibStream!.Write([0]);
+        
+        var offset = 0;
+        while (buffer.Length - offset > FlushThreshold)
+        {
+            _zlibStream.Write(buffer.Span.Slice(offset, FlushThreshold));
+            await _zlibStream.FlushAsync(cancellationToken);
+            offset += FlushThreshold;
+            if(_memoryStream.Length >= BufferSize)
+                await FlushAsync(cancellationToken);
+        }
+        
+        if (buffer.Length > offset)
+        {
+            _zlibStream.Write(buffer.Span[offset..]);
+            await _zlibStream.FlushAsync(cancellationToken);
+            _shouldFlush = true;
+        }
+        
+        if(disposeBuffer) buffer.Dispose();
+    }
+
+    private async Task FlushAsync(CancellationToken cancellationToken)
+    {
+        await _zlibStream!.FlushAsync(cancellationToken);
+        var dataSize = (int)(_memoryStream.Length - 8);
+        
+        _memoryStream.Position = 0;
+        Span<byte> buffer = stackalloc byte[4];
+        BinaryPrimitives.WriteInt32BigEndian(buffer, dataSize);
+        _memoryStream.Write(buffer);
+        _memoryStream.Write("IDAT"u8);
+
+        _memoryStream.Position = 4;
+
+        // write Crc
+        var crc = Crc32.Compute(_memoryStream, dataSize + 4);
+        BinaryPrimitives.WriteUInt32BigEndian(buffer, crc);
+        _memoryStream.Write(buffer);
+
+        _outputPipe.Advance((int)_memoryStream.Length);
+        
+        await _memoryStream.DisposeAsync();
+        _memoryHandle!.Value.Dispose();
+        _memoryHandle = null;
+        
+        _shouldFlush = false;
+    }
+
+    public async Task WriteEndOfFileAsync(CancellationToken cancellationToken = default)
+    {
+        if(_shouldFlush)
+            await FlushAsync(cancellationToken);
+        
+        Span<byte> endChunk = [
+            0x00, 0x00, 0x00, 0x00, // Length
+            0x49, 0x45, 0x4E, 0x44, // IEND
+            0xAE, 0x42, 0x60, 0x82, // Crc
+        ];
+        
+        _outputPipe.Write(endChunk);
+        Dispose();
+    }
+
+    public void Dispose()
+    {
+        if (!_disposed)
+        {
+            if (_memoryHandle != null)
+            {
+                _zlibStream!.Dispose();
+                _memoryStream.Dispose();
+            }
+            _disposed = true;
+            GC.SuppressFinalize(this);
+        }
+    }
+
+    private unsafe class RawPointerStream : UnmanagedMemoryStream
+    {
+        public void Initialize(byte* pointer, int length, int capacity)
+        {
+            Initialize(pointer, length, capacity, FileAccess.ReadWrite);
+        }
+    }
+}

Infra/ImageIntegral.cs

@@ -1,4 +1,3 @@
-using System.Buffers;
 using System.IO.MemoryMappedFiles;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -6,6 +5,7 @@ using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.PixelFormats;
 using StitchATon2.Infra.Buffers;
+using StitchATon2.Infra.Synchronization;
 
 namespace StitchATon2.Infra;
 
@@ -18,9 +18,9 @@ public class ImageIntegral : IDisposable
     private readonly int _width;
     private readonly int _height;
 
-    private IMemoryOwner<ManualResetEventSlim>? _rowLocks;
+    private ManualResetEventSlim[]? _rowLocks;
     private MemoryMappedFile? _memoryMappedFile;
-    private readonly object _lock = new();
+    private readonly Lock _lock = new();
 
     private readonly ManualResetEventSlim _queueLock = new(true);
     private readonly ManualResetEventSlim _initializationLock = new(false);
@@ -58,14 +58,14 @@ public class ImageIntegral : IDisposable
             {
                 if (_memoryMappedFile is null)
                 {
-                    Task.Factory.StartNew(() => Initialize(cancellationToken), cancellationToken);
+                    Task.Run(() => Initialize(cancellationToken), cancellationToken);
                     _initializationLock.Wait(cancellationToken);
                     _initializationLock.Dispose();
                 }
             }
         }
 
-        _rowLocks?.Memory.Span[row].Wait(cancellationToken);
+        _rowLocks?[row].Wait(cancellationToken);
     }
 
     private void Initialize(CancellationToken cancellationToken)
@@ -86,8 +86,8 @@ public class ImageIntegral : IDisposable
         }
         
         var taskQueue = backedFileStream == null
-            ? Task.CompletedTask
-            : AllocateBackedFile(backedFileStream, header);
+            ? TaskHelper.SynchronizedTaskFactory.StartNew(() => { }, cancellationToken)
+            : AllocateBackedFile(backedFileStream, header, cancellationToken);
 
         taskQueue = taskQueue.ContinueWith(
             _ =>
@@ -100,12 +100,11 @@ public class ImageIntegral : IDisposable
         // initialize resource gating, all rows is expected to be locked
         // if the backed file require to allocate, it should be safe to do this
         // asynchronously
-        var rowLocks = MemoryAllocator.AllocateManaged<ManualResetEventSlim>(_height);
-        var rowLocksSpan = rowLocks.Memory.Span;
+        var rowLocks = new ManualResetEventSlim[_height];
         for (int i = 0; i < _height; i++)
         {
             var isOpen = i < header.ProcessedRows;
-            rowLocksSpan[i] = new ManualResetEventSlim(isOpen);
+            rowLocks[i] = new ManualResetEventSlim(isOpen);
         }
 
         _rowLocks = rowLocks;
@@ -129,7 +128,7 @@ public class ImageIntegral : IDisposable
         var imageBuffer = image.Frames.RootFrame.PixelBuffer;
         
         var accumulator = Int32Pixel.Zero;
-        var buffer = MemoryAllocator.AllocateArray<Int32Pixel>(_width);
+        var buffer = MemoryAllocator.Allocate<Int32Pixel>(_width);
         var processedRows = _processedRows;
         Interlocked.Exchange(ref _queueCounter, 0);
         
@@ -143,20 +142,21 @@ public class ImageIntegral : IDisposable
                 buffer[x] = accumulator;
             }
             
-            taskQueue = QueueWriterTask(taskQueue, 0, buffer.Clone(_width), cancellationToken);
+            taskQueue = QueueWriterTask(taskQueue, 0, buffer.Clone(), cancellationToken);
             processedRows++;
         }
         else
         {
-            ReadRow(processedRows - 1, buffer);
+            ReadRow(processedRows - 1, buffer.Span);
         }
         
         if(cancellationToken.IsCancellationRequested)
             return;
 
         var prevBuffer = buffer;
-        buffer = MemoryAllocator.AllocateArray<Int32Pixel>(_width);
-        
+        buffer = MemoryAllocator.Allocate<Int32Pixel>(_width);
+        try
+        {
             for (int y = processedRows; y < image.Height; y++)
             {
                 var sourceRow = imageBuffer.DangerousGetRowSpan(y);
@@ -180,13 +180,17 @@ public class ImageIntegral : IDisposable
                     break;
 
                 var writeBuffer = prevBuffer;
-            Array.Copy(buffer.Array, writeBuffer.Array, image.Width);
+                buffer.Copy(writeBuffer, _width);
                 taskQueue = QueueWriterTask(taskQueue, y, writeBuffer, cancellationToken);
                 prevBuffer = buffer;
-            buffer = MemoryAllocator.AllocateArray<Int32Pixel>(_width);
+                buffer = MemoryAllocator.Allocate<Int32Pixel>(_width);
+            }
+        }
+        finally
+        {
+            buffer.Dispose();
         }
 
-        buffer.Dispose();
         if(cancellationToken.IsCancellationRequested)
             return;
 
@@ -205,7 +209,7 @@ public class ImageIntegral : IDisposable
     private Task QueueWriterTask(
         Task taskQueue,
         int row,
-        ArrayOwner<Int32Pixel> writeBuffer,
+        IBuffer<Int32Pixel> writeBuffer,
         CancellationToken cancellationToken)
     {
         Interlocked.Increment(ref _queueCounter);
@@ -213,10 +217,10 @@ public class ImageIntegral : IDisposable
         return taskQueue.ContinueWith(_ =>
         {
             using (var view = AcquireView(row, MemoryMappedFileAccess.Write))
-                view.WriteArray(0, writeBuffer.Array, 0, _width);
+                view.DangerousWriteSpan(0, writeBuffer.Span, 0, _width);
                 
             writeBuffer.Dispose();
-            _rowLocks!.Memory.Span[row].Set();
+            _rowLocks![row].Set();
             Interlocked.Increment(ref _processedRows);
 
             using (var view = AcquireHeaderView(MemoryMappedFileAccess.Write))
@@ -249,12 +253,6 @@ public class ImageIntegral : IDisposable
         view.DangerousReadSpan(0, buffer, 0, _width);
     }
 
-    private void ReadRow(int row, IBuffer<Int32Pixel> buffer)
-    {
-        using var view = AcquireView(row, MemoryMappedFileAccess.Read);
-        view.DangerousReadSpan(0, buffer.Span, 0, _width);
-    }
-
     private FileStream? InitializeBackedFile(string path, out Header header)
     {
         var expectedHeader = Header.CreateInitial(_width, _height);
@@ -311,7 +309,9 @@ public class ImageIntegral : IDisposable
         return fs;
     }
 
-    private static async Task AllocateBackedFile(FileStream fileStream, Header header)
+    private static Task AllocateBackedFile(FileStream fileStream, Header header, CancellationToken cancellationToken)
+    {
+        return TaskHelper.SynchronizedTaskFactory.StartNew(() =>
         {
             // The input filestream is expected to be empty with
             // initial cursor at the beginning of the file and the content
@@ -336,8 +336,8 @@ public class ImageIntegral : IDisposable
             // }
         
             fileStream.SetLength(header.Length + Header.Size);
-        
-        await fileStream.DisposeAsync();
+            fileStream.Dispose();
+        }, cancellationToken);
     }
 
     [StructLayout(LayoutKind.Sequential)]
@@ -368,11 +368,8 @@ public class ImageIntegral : IDisposable
         if (_rowLocks is { } locks)
         {
             _rowLocks = null;
-            var lockSpan = locks.Memory.Span;
             for(int i = 0; i < _height; i++)
-                lockSpan[i].Dispose();
-
-            locks.Dispose();
+                locks[i].Dispose();
         }
     }
 

Infra/Int32Pixel.cs

@@ -68,6 +68,12 @@ public record struct Int32Pixel
         return new Int32Pixel(a.R / b, a.G / b, a.B / b);
     }
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static Int32Pixel operator /(Int32Pixel a, float b)
+    {
+        return new Int32Pixel((byte)(a.R / b), (byte)(a.G / b), (byte)(a.B / b));
+    }
+
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public static explicit operator Int32Pixel(Rgb24 pixel)
     {

Infra/StitchATon2.Infra.csproj

@@ -1,14 +1,14 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>net8.0</TargetFramework>
+        <TargetFramework>net9.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
         <Nullable>enable</Nullable>
         <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     </PropertyGroup>
 
     <ItemGroup>
-      <PackageReference Include="SixLabors.ImageSharp" Version="3.1.10" />
+      <PackageReference Include="SixLabors.ImageSharp" Version="3.1.11" />
     </ItemGroup>
 
 </Project>

Infra/Synchronization/TaskHelper.cs

@@ -2,11 +2,7 @@ namespace StitchATon2.Infra.Synchronization;
 
 public static class TaskHelper
 {
-    public static TaskFactory CreateTaskFactory()
-    {
-        return new TaskFactory(
-            TaskCreationOptions.AttachedToParent,
-            TaskContinuationOptions.ExecuteSynchronously
-            );
-    }
+    public static readonly TaskFactory SynchronizedTaskFactory = new(
+        TaskCreationOptions.LongRunning,
+        TaskContinuationOptions.ExecuteSynchronously);
 }

Infra/Utils.cs

@@ -1,25 +1,16 @@
 using System.IO.MemoryMappedFiles;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-using StitchATon2.Infra.Buffers;
 
 namespace StitchATon2.Infra;
 
-public static class Utils
+internal static class Utils
 {
-    [UnsafeAccessor(UnsafeAccessorKind.Field, Name = "_buffer")]
-    private static extern ref SafeBuffer GetSafeBuffer(this UnmanagedMemoryAccessor view);
-
-    [UnsafeAccessor(UnsafeAccessorKind.Field, Name = "_offset")]
-    private static extern ref long GetOffset(this UnmanagedMemoryAccessor view);
-
     private static unsafe uint AlignedSizeOf<T>() where T : unmanaged
     {
         uint size = (uint)sizeof(T);
-        return size is 1 or 2 ? size : (uint)((size + 3) & (~3));
+        return size is 1 or 2 ? size : (uint)((size + 3) & ~3);
     }
 
-    public static void DangerousReadSpan<T>(this UnmanagedMemoryAccessor view, long position, Span<T> span, int offset, int count)
+    internal static void DangerousReadSpan<T>(this MemoryMappedViewAccessor view, long position, Span<T> span, int offset, int count)
         where T : unmanaged
     {
         uint sizeOfT = AlignedSizeOf<T>();
@@ -38,19 +29,14 @@ public static class Utils
             }
         }
 
-        var byteOffset = (ulong)(view.GetOffset() + position);
-        view.GetSafeBuffer().ReadSpan(byteOffset, span.Slice(offset, n));
+        var byteOffset = (ulong)(view.PointerOffset + position);
+        view.SafeMemoryMappedViewHandle.ReadSpan(byteOffset, span.Slice(offset, n));
     }
 
-    public static ArrayOwner<T> Clone<T>(this ArrayOwner<T> arrayOwner, int length) where T : unmanaged
+    internal static void DangerousWriteSpan<T>(this MemoryMappedViewAccessor view, long position, Span<T> span, int offset, int count)
+        where T : unmanaged
     {
-        var newArrayOwner = MemoryAllocator.AllocateArray<T>(length);
-        Array.Copy(arrayOwner.Array, 0, newArrayOwner.Array, 0, length);
-        return newArrayOwner;
-    }
-
-    public static void CopyTo<T>(this ArrayOwner<T> arrayOwner, ArrayOwner<T> target, int length) where T : unmanaged
-    {
-        Array.Copy(arrayOwner.Array, 0, target.Array, 0, length);
+        var byteOffset = (ulong)(view.PointerOffset + position);
+        view.SafeMemoryMappedViewHandle.WriteSpan<T>(byteOffset, span.Slice(offset, count));
     }
 }

StitchATon2.Benchmark/SingleTileBenchmark.cs

@@ -0,0 +1,77 @@
+using System.Net.Http.Json;
+using BenchmarkDotNet.Attributes;
+using StitchATon2.Domain;
+
+namespace StitchATon2.Benchmark;
+
+public class SingleTileBenchmark
+{
+    private const string Url = "http://localhost:5088/api/image/generate";
+    private readonly TileManager _tileManager = new(Configuration.Default);
+    private readonly Random _random = new();
+    private readonly HttpClient _client = new();
+
+    private string GetRandomCoordinatePair()
+    {
+        var maxId = _tileManager.Configuration.Rows
+                    * _tileManager.Configuration.Columns;
+        
+        var id = _random.Next(maxId);
+        var tile = _tileManager.GetTile(id);
+        return $"{tile.Coordinate}:{tile.Coordinate}";
+    }
+
+    private JsonContent GetRandomDto(float scale, float offsetX = 0, float offsetY = 0)
+    {
+        return JsonContent.Create(new
+        {
+            canvas_rect = GetRandomCoordinatePair(),
+            crop_offset = (float[]) [offsetX, offsetY],
+            crop_size = (float[]) [1f - offsetX, 1f -  offsetY],
+            output_scale = scale,
+        });
+    }
+
+    private JsonContent GetRandomDtoWithOffset(float scale)
+    {
+        var offsetX = _random.NextSingle();
+        var offsetY = _random.NextSingle();
+        return GetRandomDto(scale, offsetX, offsetY);
+    }
+
+    [Benchmark]
+    public async Task NoScaling()
+    {
+        await _client.PostAsync(Url, GetRandomDto(1f));
+    }
+    
+    [Benchmark]
+    public async Task ScaleHalf()
+    {        
+        await _client.PostAsync(Url, GetRandomDto(.5f));
+    }
+    
+    [Benchmark]
+    public async Task ScaleQuarter()
+    {
+        await _client.PostAsync(Url, GetRandomDto(.25f));
+    }
+
+    [Benchmark]
+    public async Task NoScalingWithOffset()
+    {
+        await _client.PostAsync(Url, GetRandomDtoWithOffset(1f));
+    }
+    
+    [Benchmark]
+    public async Task ScaleHalfWithOffset()
+    {        
+        await _client.PostAsync(Url, GetRandomDtoWithOffset(.5f));
+    }
+    
+    [Benchmark]
+    public async Task ScaleQuarterWithOffset()
+    {
+        await _client.PostAsync(Url, GetRandomDtoWithOffset(.25f));
+    }
+}

StitchATon2.sln

@@ -6,6 +6,10 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "StitchATon2.Domain", "Domai
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "StitchATon2.Infra", "Infra\StitchATon2.Infra.csproj", "{E602F3FC-6139-4B30-AC5A-75815E6340A4}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "StitchATon2.Benchmark", "StitchATon2.Benchmark\StitchATon2.Benchmark.csproj", "{2F9B169C-C799-4489-B864-F912D69C5D3E}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ConsoleApp", "ConsoleApp\ConsoleApp.csproj", "{D5B2A2E9-974A-43DD-A5D1-E7226CD03AFF}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -24,5 +28,13 @@ Global
 		{E602F3FC-6139-4B30-AC5A-75815E6340A4}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{E602F3FC-6139-4B30-AC5A-75815E6340A4}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{E602F3FC-6139-4B30-AC5A-75815E6340A4}.Release|Any CPU.Build.0 = Release|Any CPU
+		{2F9B169C-C799-4489-B864-F912D69C5D3E}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{2F9B169C-C799-4489-B864-F912D69C5D3E}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{2F9B169C-C799-4489-B864-F912D69C5D3E}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{2F9B169C-C799-4489-B864-F912D69C5D3E}.Release|Any CPU.Build.0 = Release|Any CPU
+		{D5B2A2E9-974A-43DD-A5D1-E7226CD03AFF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{D5B2A2E9-974A-43DD-A5D1-E7226CD03AFF}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{D5B2A2E9-974A-43DD-A5D1-E7226CD03AFF}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{D5B2A2E9-974A-43DD-A5D1-E7226CD03AFF}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 EndGlobal

global.json

@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "8.0.0",
+    "version": "9.0.0",
     "rollForward": "latestMinor",
     "allowPrerelease": false
   }