MemoryMappedFile to Span sample

MemoryMappedFileMemory.cs

using System;
using System.Buffers;
using System.IO.MemoryMappedFiles;

namespace VallmoVcdVisualizer.Services
{
    unsafe class MemoryMappedFileMemory : MemoryManager<byte>
    {
        private readonly MemoryMappedFile mmf;
        private readonly MemoryMappedViewAccessor ma;
        private readonly byte* ptr;

        public MemoryMappedFileMemory(string path)
        {
            mmf = MemoryMappedFile.CreateFromFile(path);
            ma = mmf.CreateViewAccessor(0, 0, MemoryMappedFileAccess.Read);
            ma.SafeMemoryMappedViewHandle.AcquirePointer(ref ptr);
        }

        public ReadOnlySpan<byte> GetROSpan() => GetSpan();

        public override Span<byte> GetSpan()
        {
            return new Span<byte>(ptr, (int)ma.Capacity);
        }

        public override MemoryHandle Pin(int elementIndex = 0)
        {
            throw new NotImplementedException();
        }

        public override void Unpin()
        {
            throw new NotImplementedException();
        }

        protected override void Dispose(bool disposing)
        {
            ma.SafeMemoryMappedViewHandle.ReleasePointer();
            mmf.Dispose();
            ma.Dispose();
        }
    }
}