Quick demo of mmap in dotnet

MemoryMap.cs

using System.IO.MemoryMappedFiles;
using System.Runtime.InteropServices;

namespace MemMapTests; 

internal static class Program
{
    private const long Megabyte = 1048576;
    private const long Kilobyte = 1024;

    private static void Main()
    {
        Console.WriteLine("Hello World!");
        
        var offset = 128 * Megabyte;
        var length = 1 * Kilobyte;

        using var mmf = MemoryMappedFile.CreateFromFile(@"C:\Users\Iain\Desktop\bigfile.zip", FileMode.Open, null);
        using var accessor = mmf.CreateViewAccessor(offset, length);
        
        int colorSize = Marshal.SizeOf<SomeData>();
        for (long i = 0; i < length; i += colorSize)
        {
            accessor.Read<SomeData>(i, out var data);
            //accessor.Write(i, ref data);
                    
            Console.WriteLine($"Chunk of data at {offset:X8}+{i:X4} -> {data.A:X8} {data.B:X8} {data.C:X8} {data.D:X8}");
        }
    }
}

[StructLayout(LayoutKind.Sequential)]
public struct SomeData
{
    public uint A;
    public uint B;
    public uint C;
    public uint D;
}